R E S E A R CH A R T I C L E Soil properties and phytochemical analysis of spleen amaranth (Amaranthus dubius Mart. Ex Thell.) from Ankole and Teso sub-regions of Uganda: Implications for management and prevention of hyperglycemia Caroline Asekenye1,2 | Paul E. Alele3 | Patrick E. Ogwang1 | Eunice A. Olet4 1Department of Pharmacy, Faculty of Medicine, Mbarara University of Science and Technology, Mbarara, Uganda 2Department of Pharmacy, Faculty of Health Sciences, Victoria University, Kampala, Uganda 3Department of Pharmacology and Therapeutics, Faculty of Medicine, Mbarara University of Science and Technology, Mbarara, Uganda 4Department of Biology, Faculty of Science, Mbarara University of Science and Technology, Mbarara, Uganda Correspondence Caroline Asekenye, Department of Pharmacy, Faculty of Medicine, Mbarara University of Science and Technology, Mbarara, Uganda. Email: 2019phd003@std.must.ac.ug Funding information Pharm-Bio Technology and Traditional Medicine Centre, Mbarara University of Science and Technology ABSTRACT Background: The current authors reported a remarkably higher prevalence of hypergly- cemia in Ankole than in the Teso sub-region of Uganda, and Amaranthus dubius was documented among the frequently eaten leafy vegetables in both sub-regions. In an attempt to investigate this remarkable variance in the prevalence of hyperglycemia and find alternative therapies for hyperglycemia, we assessed the influence of soil properties on phytochemical quantity in spleen amaranth (A. dubius) from the two sub-regions. The soil properties and vegetable phytochemicals were quantified using spectrophotometric methods. Results: Soil pH, organic matter (OM), and nitrogen (N) were higher in soil samples from the Teso sub-region than those from the Ankole sub-region. The Teso sub-region had sandy loam soils that were relatively low in exchangeable cations, whereas Ankole had clay loam soils. Total tannin content (TTC) and total saponin content (TSC) were signifi- cantly higher in A. dubius samples from the Teso sub-region, and total alkaloid content (TAC) was higher in vegetable samples from Ankole. The Pearson’s correlation results showed a significant relationship between pH and TTC, N, and TAC. Total flavonoid con- tent (TFC) was correlated with exchangeable cations. Conclusion: High soil pH, N, cations, and sand percentage found in soil samples from the Teso sub-region supported the biosynthesis of polyphenolic compounds in the vegetable samples. By implication, this consequently benefited its consumers by reducing blood glucose levels ultimately reducing the prevalence of hyperglycemia in the region. K E YWORD S Amaranthus dubius, phytochemicals, soil properties, Uganda INTRODUCTION The relentlessly increasing prevalence of hyperglycemia is dependent on factors like the geographical region of residence and diet.1,2 This trend is similar in Uganda, as reported by Asekenye et al. and Bahendeka et al.,3,4 where a remarkably higher prevalence of hyper- glycemia was found in Ankol than in the Teso sub-region. Additionally, Asekenye et al. and Kabwama et al.3,5 also documented higher con- sumption of vegetables in the Teso sub-region than in the Ankole sub-region. In an attempt to further investigate this remarkable Received: 27 February 2025 Revised: 9 June 2025 Accepted: 12 August 2025 DOI: 10.1002/jsf2.70018 This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. © 2025 The Author(s). JSFA Reports published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. 418 JSFA Reports. 2025;5:418–430.wileyonlinelibrary.com/journal/jsf2 https://orcid.org/0009-0007-7218-2738 mailto:2019phd003@std.must.ac.ug http://creativecommons.org/licenses/by/4.0/ http://wileyonlinelibrary.com/journal/jsf2 http://crossmark.crossref.org/dialog/?doi=10.1002%2Fjsf2.70018&domain=pdf&date_stamp=2025-08-26 variance in the prevalence of hyperglycemia and find alternative ther- apies, we designed this study as part of an ongoing larger study to assess the influence of soil properties on Amaranthus dubius phyto- chemicals, since it was eaten in both sub-regions. Our working hypothesis was that since the soil properties influence phytochemicals in plants and since sub-regions in Uganda have significant differences in climatic conditions and soil properties,6,7 the different samples of A. dubius (a widely eaten vegetable in Uganda) could have significantly different phytochemical quantities, thereby helping to explain the sig- nificant difference in the prevalence of hyperglycemia in these study sub-regions. To test this hypothesis, we studied the phytochemical quantity and soil properties in the vegetable and soil samples, respec- tively, from these two study sub-regions. The results aided in estab- lishing a correlation between soil properties and phytochemicals, shedding more light on the remarkable variance in prevalence of dis- ease like hyperglycemia between the studied sub-regions. This, in turn, suggests alternative strategies for reducing hyperglycemia. Fur- thermore, these results can be used to maximize vegetable production for medicinal purposes. Phytochemicals (plant bio-actives or secondary metabolites (SMs)) are defined as non-nutrient compounds in plants responsible for protecting them against unfavorable conditions (nutrient insuffi- ciency, harsh environment, and plant pathogens) and attraction of pol- linators.8,9 These unfavorable conditions induce the activation of genes involved in the biosynthesis of SMs.10,11 There are large and diverse classes of SMs (alkaloids, flavonoids, saponins, tannins, pheno- lics, and terpenoids) that accumulate in plant organs like fruits, leaves, flowers, and roots. Amaranthus dubius is a cultivar that grows voluntarily and/or is cultivated mostly for its leaves in Africa, Southeast Asia, and Central America12 for food, since it yields significantly within the shortest period.13 Recently, it was adopted in the global progress in reducing nutrient-related challenges, especially in developing countries,12,14 due to the macro- and micronutrients, minerals, vitamins, dietary fiber, low carbohydrate, and calorie elements it contains.15–17 Some studies have found higher nutrient content in Amaranthus species than in some cruciferous species (cabbage and lettuce).18,19 The popular anti- oxidant health benefit of the genus Amaranthus is credited to its phy- tochemicals like polyphenols (flavonoids, phenolic acids, and tannins) and terpenes (squalene), where some isolations from the matrix have been done using various solvents (20–22).20–22 The biosynthesis of these phytochemicals is influenced by a vast array of factors, like genotype/species and climatic conditions (23–25).23–25 Ankole and Teso sub-regions of Uganda do have completely different climatic conditions that may result in different soil properties and ultimately differently influence the induction of genes responsible for the phyto- chemicals in the vegetable species. Soil physical properties, including pH, organic matter (OM), and texture, and chemical properties, such as nitrogen, phosphorus, potas- sium, calcium, sodium, and iron, were looked at in this study. These properties influence the production of phytochemicals in plants by determining the biological activity, solubility of nutrients, and oxidation and reduction processes in the soil and hence affect the form of interaction between the soil and the plants.26–28 OM is the summation of plant and animal residues in the soil at various stages of decomposi- tion. Its percentage has been found to affect the soil nutrients in the soil and hence the phytochemicals synthesized in the plant. A study on let- tuce showed that the vegetables grown under organic manure increased certain phenolic compounds, and increased organic fertilizer application tended to have a negative effect on its phytochemical con- tent.29 A decrease of flavonoid and phenolic acid concentrations has been observed in leaves of organically grown barley as a result of increasing fertilization rates using farmyard manure or cattle slurry.30 Soil texture is the relative proportions of sand, clay, and silt parti- cles in the soil. When Lata and Winska grew Kale (Brassica oleracea acephala group) in lessive soil, the plants were found to contain more anthocyanins, glutathione, and ascorbate compared to those grown in muddy soil.31 Addition of OM to the soil improved its texture and structure, and when plants were grown in humus-rich soil, they pro- duced more quantities of phenolic compounds compared to those grown in less humus-rich soil.32 Sandy clay textured soils do not sup- port phytochemical accumulation, especially the terpenes found in essential oils, whereas luvisolic soils, characterized by high clay con- tent, were reported to support the accumulation of phenolic com- pounds in Iris species.33 pH is the potential of hydrogen, a measure of the acidity or alkalinity of a soil solution. It is an important factor for solubility, breakdown, and formation of nutrients in the soil. Isothio- cyanates are usually produced in plants grown in a neutral to acidic pH range.34,35 Acidic soils promote nitrification and carbon substrate utilization, which is characterized by vegetation that produces terpe- nic and polyphenolic phytochemicals.36 Supplementary soil nutrition is a common agronomical practice to enhance soil fertility by the addition of either organic/inorganic macro- elements (nitrogen, phosphorus, and/or potassium) and/or trace- elements (calcium, magnesium, sodium, etc.). This does not only stimu- late plant growth in general, but also influences SMs production. Many studies have concluded that soil fertility levels of these nutrients do play a role in influencing the phytochemical accumulation in plants37–39 although it has been noted that the application of these fertilizers sin- gly, in pairs, or as a compound does lead to inconsistent results.40 Nitro- gen deficiency that can inhibit primary metabolism (poor growth and reduced protein synthesis) has been proposed to affect the nitrogen balance in plants, which may instead favor secondary metabolism and the accumulation of several phenolic compounds and glucosino- lates.41,42 Stewart et al.43 noted a significant inverse correlation between the availability of nitrogen and phosphorus in the soil and of flavonol content in Arabidopsis and tomato seedling tissues. However, the concentration of quercetin and kaempferol was noted to increase in response to either nitrogen or phosphorus alone in the same plants. According to the phenylpropanoid metabolic pathway, it has long been reported that phenolic compounds in plants may accumulate due to a deficiency in nitrogen, phosphate, and iron in the soil.44,45 Alkaloids are nitrogen-based phytochemicals, and generally, their synthesis and accumulation is in response to increased soil nitrogen fertilization. Barlog et al. applied magnesium and nitrogenous fertil- izers on Lupinus angustifolius, and it influenced an increase in alkaloid SOIL PROPERTIES AND PHYTOCHEMICAL ANALYSIS 419 25735098, 2025, 12, D ow nloaded from https://scijournals.onlinelibrary.w iley.com /doi/10.1002/jsf2.70018 by M akerere U niversity, W iley O nline L ibrary on [19/03/2026]. See the T erm s and C onditions (https://onlinelibrary.w iley.com /term s-and-conditions) on W iley O nline L ibrary for rules of use; O A articles are governed by the applicable C reative C om m ons L icense concentration by 9%–17%.46 In other studies, alkaloid production (in Lapinus albus) was only in response to various amounts of nitrogen supplementation.47 For example, Sangral is a commercial compound fer- tilizer; when applied to Datura innoxia plants at a rate of 600 kg ha�1, the alkaloids peaked and then decreased at 800 kg ha�1.48 In the case of terpenic compounds (e.g., monoterpene), although they are carbon- based phytochemicals, their concentration in a plant did respond to nitrogen fertilization.49 For instance, the application of nitrogen fertilizer increased the concentration of monoterpenes in Thuja plicata during its active growth stage, and when the plant growth began to subside, con- tinuous fertilizer application generated even higher amounts of monoterpenes.50 Soil cations are introduced to the soil via mineral fertilizers like sodium chloride, calcium carbonates, etc., and they bind to the soil par- ticles. Depending on the exchange capacity in the soil, these cations can be released into the soil and become available to the plant.51,52 Saline soil can cause oxidative stress to the plant due to the pro- duction of reactive species.53 Plants respond to this kind of stress by producing SMs that can scavenge and/or detoxify these reactive spe- cies.54 For example, when Aegiceras corniculatum was treated with 250 mM of sodium chloride (NaCl), the polyphenolic content increased more than double compared to the controls.55 The accumu- lation of polyphenols in a Tunisian seaweed (Cakile maritima) was due to the treatment with different concentrations of NaCl salt. Salinity also influences the accumulation of some terpenic compounds in the plants. Cineole and camphor in Rosmarinus officinalis were induced by treatment with 100 mM NaCl; however, there was a slight decrease in borneol, α-terpineol, nopol, and camphene monoterpenes.56 In the light of these previous studies, it is clear that despite the veg- etable species, environmental conditions (climate and soil properties) that are “harsh”/“abnormal” to a plant, favor the phytochemical synthe- sis in it. We, therefore, designed this study to assess the influence of soil properties on the phytochemical content in A. dubius from Ankole and Teso sub-regions of Uganda. Specifically, the phytochemical classes in the aqueous leaf extracts and soil properties were quantified. Data from these variables were correlated to find the relationship between them. MATERIALS AND METHODS Materials A flame photometer PFP7 (JENWAY, United Kingdom) and an atomic absorption spectrophotometer AAS990, AAS932+ (PG Instruments, United Kingdom) were used due to their selective detection of the studied soil nutrients. An ultra–violet/visible (UV–Vis) 6705 spectro- photometer (JENWAY, United Kingdom) was better fitted for quantify- ing the colored solutions of the vegetable leaf extracts, within the UV range. More materials including a pH meter (Mettler Toledo, JENWAY, United Kingdom), a porcelain mortar and pestle, a vortex machine, and an electric high speed shaker were used for homogenization of soil sus- pension. Most of these equipment were acquired from Bruker, United States of America. The chemical standards used were quercetin, gallic acid, diosgenin, and atropine. More chemicals and reagents were Folin-Ciocalteu, aluminum chloride, sodium acetate, vanillin, sulfuric acid, hydrochloric acid, bromocresol green, and puremethanol. Distilled water was from a Milli-Q purification system (Millipore, India). The standards and some of these chemicals were purchased from Sigma- Aldrich, Germany, andwere of analytical grade. Methods Study site characteristics The Ankole sub-region is located in the South-Western part of Uganda, with geographical coordinates of Latitude: 00 290 59.9900 N and Longitude: 00 290 59.990 E. Its average elevation is 394 m, and the study sampled districts (Ibanda, Kiruhura, Mbarara, Rubirizi, and Ntugamo) lie at about 1806 m above sea level. This region experi- ences a relatively higher average annual rainfall of 1018 mm, and a lower average annual temperature of 17.2�C, making it generally cooler (https://en.wikipedia.org/wiki/Ankole_sub-region). Teso sub-region is in the eastern part of Uganda with coordinates of Latitude: 1.71590 N and Longitudes: 33.61110 E. Its study districts (Soroti, Ngora, Amuria, Kaberamaido, and Katakwi) lie about 1129 m above sea level, with an average elevation of 1081 m. It has an aver- age annual rainfall of about 1000 mm, and the average annual temper- ature is about 25�C, making it semi-arid (https://en.wikipedia.org/ wiki/Teso_sub-region). Figure 1 shows the map showing the sampling points in the Ankole and Teso sub-regions of Uganda. Soil and vegetable sample collection Vegetable gardens (from the sampled districts) were subdivided into rela- tively uniform sampling units. Within each unit, about 200 g of soil sam- ples were randomly collected 12 inches from the surface, from several different locations, and mixed into one composite sample. From each garden, a portion of the composite sample was transferred to a soil sam- ple bag, which was well labeled with date, name of place, sample, and garden number, and GPS coordinates.57–59 The soil samples were then taken to the laboratory (Soil, Plant and Water Analytical Laboratory, Col- lege of Agricultural and Environmental Sciences, Makerere University, Kampala City, Uganda) for analysis. The samples were air dried at 25�C for 5 days to eliminate moisture. Afterward, they were ground using a porcelain pestle and mortar and then sieved through a 2 mm sieve to remove debris and other non-soil materials.60,61 The sieved soil samples were analyzed for their physical and chemical properties, and they included soil pH, soil OM, nitrogen (N), available phosphorus (av. P), exchangeable calcium (Ca2+), magnesium (Mg2+), sodium (Na+), potas- sium (K+), iron (Fe), and soil texture (the percentage proportions of sand, clay, and silt). N, P, and K are generally the most limiting macronutrients regulating plant growth and are tightly linked to secondary metabolism in terrestrial ecosystems.62,63 For example, P uptake is promoted under low N conditions.64 Phenolic and glucosinolate compounds are synthesized 420 ASEKENYE ET AL. 25735098, 2025, 12, D ow nloaded from https://scijournals.onlinelibrary.w iley.com /doi/10.1002/jsf2.70018 by M akerere U niversity, W iley O nline L ibrary on [19/03/2026]. See the T erm s and C onditions (https://onlinelibrary.w iley.com /term s-and-conditions) on W iley O nline L ibrary for rules of use; O A articles are governed by the applicable C reative C om m ons L icense https://en.wikipedia.org/wiki/Ankole_sub-region https://en.wikipedia.org/wiki/Teso_sub-region https://en.wikipedia.org/wiki/Teso_sub-region depending on the demand for N nutrients.65 Terpenic and alkaloids are synthesized based on the trade-off of carbon from the carbon–nitrogen balance in the plant. Soil physical properties are necessary for retention, solubility, and availability of soil chemicals to the plant (66).66 At the same time, samples of A. dubius leaves were collected (at the end of the vegetative stage (when they are fully mature, and before the leaf nutrients and phytochemicals are used up for flower- ing) from the same garden points where the soil samples were col- lected. It was taken for identification and was given a voucher number (51176) by a botanist. The leaves were put in plastic bags with similar labels to the soil samples,67 and taken to the Pharmaceutical Sciences Laboratory, Mbarara University of Science and Technology (Mbarara City, Uganda) for phytochemical analysis. Laboratory analysis of soil physical and chemical properties Soil pH Soil pH was measured by a pH meter using soil/solution suspension.68–70 Organic matter (OM) OMwas determined following wet oxidation using concentrated sulfuric acid and potassium dichromate.71–73 Soil, potassium dichromate, and concentrated sulfuric acid digest was titratedwith ferrous ammonium sul- fate solution. The amount of organic carbon in the soil is a measure of the used potassium dichromate, which is the difference between the added and the residual. The organic carbonwas calculated using Formula 1 Organic Carbon %ð Þ¼ T�0:3�0:2�100 Sample weight � � �75% ð1Þ where T is the difference in the titer, 0.3 is the indicator volume, 0.2 is the concentration of ferrous ammonium sulfate, and 75% is the oxida- tion completion factor. The organic carbon is 58% of OM, shown in Formula 2. Organic matter¼ O:C�100ð Þ=58 ð2Þ Soil particle size (soil texture) analysis Soil texturewas analyzed using the hydrometer/Bouyoucosmethod.74–76 F I GU R E 1 Map showing the sampling points in the Ankole and Teso sub-regions of Uganda (drawn from GPS coordinates from November 2023 using Arc GIS version 10.5 on 10/12/2023). SOIL PROPERTIES AND PHYTOCHEMICAL ANALYSIS 421 25735098, 2025, 12, D ow nloaded from https://scijournals.onlinelibrary.w iley.com /doi/10.1002/jsf2.70018 by M akerere U niversity, W iley O nline L ibrary on [19/03/2026]. See the T erm s and C onditions (https://onlinelibrary.w iley.com /term s-and-conditions) on W iley O nline L ibrary for rules of use; O A articles are governed by the applicable C reative C om m ons L icense The hydrometer and temperature readings were taken from a thoroughly mixed soil suspension allowed to stand undisturbed for 2 h. The percentage of sand content (after 40 seconds): the hydrome- ter reading, which reflects the grams of silt and clay in the soil suspen- sion. This value was subtracted from the original soil sample weight to get the amount of sand and was converted to a percentage form. The percentage clay: the hydrometer reading (after 2 h) reflects the clay content of the original suspension and is converted to a percentage. Each hydrometer reading was taken after temperature correction. Silt content was calculated by subtracting the sum of clay and sand con- tents from 100%. Analysis of soil N, Fe, available P, and exchangeable cations (Na+, Ca2+, K+, and Mg2+) Mg2+ and Fe were analyzed using an atomic absorption spectropho- tometer (AAS) on Mehlich 1 extracts. K+, Ca2+, and Na+ were ana- lyzed using a flame photometer on the same extract.77,78 Available P content was determined using a spectrophotometer at 882 nm wave- length after the extracts’ reaction with ammonium molybdate in the presence of ascorbic acid.79 The standard working solutions were measured to calibrate the instrument. The concentration of the above ions was calculated using Formula 3 a�bð Þ�V � fð Þ=W ð3Þ where a is the concentration of K, Ca, Na, and Mg in the soil extract, b is the concentration of the element in the blank extract, V is the vol- ume of extract solution, W is the weight of the soil sample, and f is the dilution factor. N was determined calorimetrically at a wavelength of 655 nm on the complexed digestion mixtures using N1 and N2 reagents.80 Reagents in N1: sodium salicylate, sodium citrate, sodium tartrate, and sodium nitroprusside. Reagents in N2: sodium hydroxide and sodium hypochlorite (JIK), mixed in the stipulated proportions by Okalebo et al.81 Quantification of phytochemicals in A. dubius vegetable samples A. dubius aqueous leaf extracts (AdALEs) were prepared by boiling 100 g of ground leaves in 1000 mL of distilled water for 15 min.82 After cooling, the mixture was filtered, and the filtrate was dried in a freeze dryer. Total flavonoid content (TFC) TFC in AdALEs was determined using a modified aluminum chloride (AlCl3) colorimetric method by Baba et al., and Khan et al83,84 To I mL (1 mg/mL) of each AdALEs, 3 mL of methanol was added and agitated, followed by the addition of 0.2 mL of 10% AlCl3 solution and 0.2 mL of 1 M sodium acetate. Thereafter, the solutions were incubated for 30 min at room temperature in the dark. The absorbance of the resul- tant solutions was then read at 420 nm using a UV–vis spectropho- tometer. Quercetin was used as the standard compound. The concentration of TFC in AdALEs was determined using the equation y = 0.0158x � 0.3077 and R2 = 0.9173 obtained from a standard quercetin curve. The TFC was expressed as microgram quercetin equivalent of flavonoids (QEF) per milligram of vegetable dry weight (d. wt). Total saponin content (TSC) TSC in AdALEs was determined using a vanillin–sulfuric acid assay.85,86 To 1 mL (1 mg/ML) of each AdALEs was added 0.5 mL of 8% (w/v) vanillin solution, followed by addition of 5 mL of 72% (v/v) sulfuric acid, and thoroughly mixed. The resultant mixtures were then incubated at 60�C in a shaking water bath for 15 min and then cooled in ice-cold water for 5 min. The absorbance of the resultant solutions was then read at 550 nm using a UV–vis spectrophotometer. Dios- genin was the standard chemical used. The concentration of TS com- pound in the AdALEs was determined using the equation y = 0.0049x + 0.0504 and R2 = 0.9917 obtained from a standard diosgenin curve. The TSC was expressed as microgram diosgenin equivalents of saponin (DES) per milligram of vegetable dry weight (d. wt). Total phenolic content (TPC) The TPC in AdALEs was determined using a modified Folin-Ciocalteu method.87,88 To 1 mL (1 mg/mL) of AdALEs was added 2 mL of 10% Folin-Ciocalteu reagent, followed by the addition of 2 mL of 7.5% (w/v) sodium carbonate solution, and incubated at 40�C for 30 min. The absorbance of the resultant solution was then read at 760 nm. Working solutions of gallic acid were used to prepare a calibration curve for the standard. The concentration of TP compound in the AdALEs was determined using the equation y = 0.0207x + 0.0368 and R2 = 0.945 obtained from a standard gallic acid curve. The TPC was expressed as microgram gallic acid equivalent per milligram (GAE) of A. dubius dry weight. Total tannin content (TTC) TTC was determined using a modified vanillin-hydrochloric acid assay method.89,90 To 1 mL (1 mg/mL) of AdALEs was added 1500 μL of vanillin/methanol (4%) solution and 750 μL of concentrated HCl, and they were allowed to react at room temperature for 1 h. The absor- bance at 300 nm was measured against a blank. Gallic acid was used as the standard. The concentration of the TTC compound in AdALEs was determined using the equation y = 0.011x + 0.0353 and R2 = 0.9358 obtained from a standard gallic acid curve. The concen- tration of condensed TT was expressed in micrograms of gallic acid equivalents (GAE) per milligram dry weight. Total alkaloid content (TAC) TAC was determined following a reaction with bromocresol green (BCG).91–93 AdALEs were dissolved in 2 N HCl and then filtered. 1 mL 422 ASEKENYE ET AL. 25735098, 2025, 12, D ow nloaded from https://scijournals.onlinelibrary.w iley.com /doi/10.1002/jsf2.70018 by M akerere U niversity, W iley O nline L ibrary on [19/03/2026]. See the T erm s and C onditions (https://onlinelibrary.w iley.com /term s-and-conditions) on W iley O nline L ibrary for rules of use; O A articles are governed by the applicable C reative C om m ons L icense (1 mg/mL) of each solution was washed (three times) with 10 mL of chloroform in a separating funnel. The pH of this solution was adjusted to neutral with 0.1 N NaOH. Thereafter, 5 mL of BCG solu- tion and 5 mL of phosphate buffer were added to these solutions. The mixtures were shaken and complexes extracted with 1, 2, 3, and 4 mL of chloroform by vigorous shaking; the extracts were then collected in a 10 mL volumetric flask and made up to 10 mL with chloroform. The absorbance of the complex in chloroform was measured at 470 nm. The concentration of TAC in the AdALEs was determined using the equation y = 0.0023x + 0.0389 and R2 = 0.954 obtained from a standard atropine curve. The total concentration of alkaloid was expressed in micrograms of atropine equivalent per milligram of vege- table dry sample. All extraction procedures were performed in triplicate (n = 3) for each AdALE from the vegetable samples. Statistical analysis Analysis of variance (One way) was performed to determine any signifi- cant difference between the soil properties, phytochemical quantities in A. dubius, from the sampled districts and study sub-regions. Where necessary, Tukey’s test (p < 0.05) to find out where the significant dif- ference is was performed. A two-sample t-test was also performed to find out whether the means of the soil properties and phytochemical quantities in AdALEs differ significantly between the study sub-regions. Pearson’s correlation analysis between phytochemical quantities in A. dubius and the soil properties was performed to see the direction and strength of their relationship. Minitab version 19 statistical soft- ware was used for the analysis of data. RESULTS Physical and chemical properties of soil samples from Ankole and Teso sub-regions of Uganda The soil pH, N, OM, available P, and texture were significantly (p < 0.05) different in the study sub-regions. Soil samples from Teso sub-region had a pH of 7, whereas those from Ankole sub-region had a pH of 6.4. OM percentage is higher in soil samples from Teso sub-region, whereas available P is higher in samples from Ankole sub-region. Soils from Ankole sub-region have less sand, higher clay, and silt percentage com- pared to those from Teso sub-region. The difference in the quantity of soil minerals in soil samples from the study sub-regions was not statisti- cally significant (p > 0.05). More of this result is in Table 1. Physical and chemical properties of soil samples from the study districts A significantly (p < 0.05) higher average pH (7.7) was recorded in the soil samples from Ngora district. OM percentage was significantly (p < 0.05) highest in soil samples from Soroti district (51.3%), and the least from Kiruhura and Kaberamaido districts. Available P is significantly higher in samples from Rubirizi district (25.8 mg/kg), whereas soil samples from Katakwi district had sig- nificantly the least amount (0.04 mg/kg). It is also noticeable that soil samples from Katakwi district had significantly highest sand, the least clay, and silt percentages among all the study districts (79.7%, 15.5%, and 3.9%, respectively). There was no significant (p > 0.05) difference among the exchangeable cations (K+, Na+, Ca2+, and Mg2+) and Fe in the soil samples across the study dis- tricts; however, soil samples from Ntungamo district contained the highest K+, Fe, and Mg2+ concentrations, whereas Ca and Na were highest in Rubirizi and Kiruhura, respectively. Table 2 has more of this result. Phytochemical quantities in aqueous leaf extracts of Amaranthus dubius from Ankole and Teso sub-regions The total phenolic content (TPC), TTC, and TSC were higher in A. dubius samples from the Teso sub-region, with the latter two phyto- chemicals being significantly (p < 0.05) higher. TFC and TAC were, however, higher in the Ankole sub-region, though not at statistically significant levels (p > 0.05), as shown in Table 3. Phytochemical quantification in aqueous leaf extracts of Amaranthus dubius samples from study districts There are some significant differences in the phytochemical quan- tity in A. dubius across the study districts. Samples from Ngora dis- trict had significantly (p < 0.05) the highest quantity of TTC (60.2 mg/g d.wt), whereas the least quantity (11.5 mg/g d.wt) was found in the samples from Ibanda district. Vegetable samples from Rubirizi district had significantly the least quantity of TSC (37.9 mg/g d.wt) compared to those from Soroti district, which had significantly the highest quantity (152.5 mg/g d.wt). TPC quantity is significantly (p < 0.05) the highest (34.9 mg/g d.wt) in Kiruhura district and significantly the least in Rubirizi district (20.9 mg/g d. wt). A. dubius samples from Kaberamaido and Katakwi districts had significantly (p < 0.05) the highest (126.5 mg/g d.wt) and the low- est (22.8 mg/g d.wt) quantities of the TAC, respectively. The dif- ference in quantity of TFC is insignificant (p > 0.05) in the vegetable samples across the study districts. More of these results are included in Table 4. Pearson’s correlation between soil properties and phytochemical quantities in A. dubius samples According to the results detailed in Table 5, most of the correlations between the phytochemicals in A. dubius and soil properties were positive. TTC in A. dubius was the only significant (p < 0.05) and SOIL PROPERTIES AND PHYTOCHEMICAL ANALYSIS 423 25735098, 2025, 12, D ow nloaded from https://scijournals.onlinelibrary.w iley.com /doi/10.1002/jsf2.70018 by M akerere U niversity, W iley O nline L ibrary on [19/03/2026]. See the T erm s and C onditions (https://onlinelibrary.w iley.com /term s-and-conditions) on W iley O nline L ibrary for rules of use; O A articles are governed by the applicable C reative C om m ons L icense positively correlated phytochemical with the soil pH. The correlation between the TSC and OM, and N was positive and significant (p < 0.05), and this relationship was even stronger and highly signifi- cant with N. The relationship between TAC in the vegetable and the soil properties was not significant (p > 0.05) except for that with N and the percentage of sand. Most cations (K+, Na+, Mg2+) in the soil were positively correlated with the quantity of TFC in A. dubius. The strength of the relationship was strong and highly significant. Clay percentage in the soil did not have any significant correlation with the vegetable phytochemical quantity regardless of the direc- tion of the relationship. DISCUSSION This study was part of the ongoing larger study to investigate the remark- able difference in the prevalence of hyperglycemia in Ankole and Teso sub-regions of Uganda, and to ultimately find prevention and/or treat- ment therapies via consumption of appropriate vegetables in the tradi- tional diet. Bahendeka et al., and the current authors,3,4 have already reported the other factors (economic status, vegetable consumption, and other lifestyle factors) associated with the prevalence of hyperglycemia in the study sub-regions, and based on these previous studies, we hypothe- sized that the vegetables could be influenced (at the phytochemical level) T AB L E 1 Physical and chemical properties (mean ± standard deviation) of soil samples from the Ankole and Teso sub-regions of Uganda. Sub- region pH N OM Av. P Fe Sand Clay Silt K+ Na+ Ca2+ Mg2+ Percent (%) Milligram per kilogram (mg/kg) Percent (%) Centimoles per kilogram (Cmol/kg) Ankole 6.4 ± 0.51 0.2 ± 0.05 3.6 ± 1.36 25.8 ± 24.5 75.3 ± 18.8 60.6 ± 5.60 33.2 ± 7.12 11.3 ± 4.43 0.6 ± 0.49 0.5 ± 0.29 5.81 ± 1.88 0.7 ± 0.30 Teso 7.0 ± 0.60 0.9 ± 0.49 28.1 ± 25.70 0.1 ± 0.14 78.4 ± 4.03 72.3 ± 6.54 22.5 ± 6.83 5.7 ± 1.75 0.3 ± 0.21 0.5 ± 0.12 6.3 ± 0.62 0.6 ± 0.10 p-value 0.02* 0.00* 0.02* 0.00* 0.60 0.00* 0.00* 0.00* 0.06 0.48 0.40 0.56 Note: p-values less than 0.05 are statistically significant (bold value*). N: nitrogen, O.M: organic matter, av. P: available phosphorus, Fe: iron, K+: potassium ions, Na+: sodium ions, Ca2+: calcium, Mg2+: magnesium. T AB L E 2 Physical and chemical properties (mean ± standard deviation) of soil samples from the sampled districts. Soil property Rubirizi Ibanda Ntungamo Kiruhura Katakwi Kaberamaido Soroti Ngora pH 6.6 ± 0.41ab 6.4 ± 0.24b 6.3 ± 0.10b 6.3 ± 1.05b 6.9 ± 0.11ab 6.2 ± 0.03b 7.0 ± 0.01ab 7.7 ± 0.52a* % OM 4.8 ± 1.39cd 4.1 ± 1.06cd 3.42 ± 0.34d 1.9 ± 0.41d* 7.8 ± 0.16c 1.8 ± 0.04d* 51.3 ± 3.62a* 19.4 ± 0.72b N 0.2 ± 0.02cd 0.2 ± 0.03cd 0.1 ± 0.01d* 0.1 ± 0.02d* 0.4 ± 0.11cd 1.6 ± 0.11a* 1.0 ± 0.01ab 0.7 ± 0.53bc Sand 56.0 ± 0.00d 60 ± 3.46d 60.7 ± 5.77d 65.7 ± 7.51bcd 79.7 ± 0.57a* 62.7 ± 3.06cd 73.7 ± 0.58ab 73.0 ± 1.00abc Clay 29.3 ± 2.31bc 30 ± 40bc 30 ± 0.00bc 43.3 ± 7.09a 15.7 ± 0.46d* 33.0 ± 3.00b 21.3 ± 1.12cd 19.9 ± 0.02d Silt 14.7 ± 2.31a 10.0 ± 5.29ab 9.3 ± 5.77ab 11.0 ± 4.00ab 3.9 ± 0.17b* 6.5 ± 2.20ab 5.2 ± 1.089b 7.2 ± 1.06ab mg/kg Av. P 55.5 ± 29.60a* 2.6 ± 0.02b 9.5 ± 5.73b 31.6 ± 9.08ab 0.04 ± 0.01b* 0.3 ± 0.26b 0.1 ± 0.00b 0.1 ± 0.00b Fe 75.0 ± 5.29a 80.3 ± 4.04a 95.0 ± 18.5a 51.0 ± 7.21b 77.0 ± 2.00a 80.3 ± 1.16a 73.7 ± 3.51a 82.7 ± 1.53a Cmol/ kg K+ 0.8 ± 0.46a 0.3 ± 0.05a 0.8 ± 0.74a 0.6 ± 0.61a 0.2 ± 0.01a 0.1 ± 0.01a 0.6 ± 0.01a 0.35 ± 0.00a Na+ 0.5 ± 0.21ab 0.3 ± 0.01b* 0.6 ± 0.41ab 0.8 ± 0.14a* 0.36 ± 0.03ab 0.5 ± 0.18ab 0.6 ± 0.03ab 0.5 ± 0.01ab Ca2+ 7.5 ± 2.13a 4.3 ± 0.07b 4.7 ± 1.81ab 6.8 ± 0.58ab 5.8 ± 0.01ab 5.9 ± 0.18ab 7.3 ± 0.21a 6.24 ± 0.23ab Mg2+ 0.8 ± 0.14a 0.6 ± 0.19ab 0.8 ± 0.35a 0.3 ± 0.21b 0.5 ± 0.03ab 0.6 ± 0.03ab 0.7 ± 0.05ab 0.6 ± 0.03ab Note: Values in the same row that do not share a letter are significantly different, and bold value* is statistically significant = p < 0.05. T AB L E 3 Phytochemical quantities (mean ± standard deviation) in aqueous leaf extracts of Amaranthus dubius samples from the study Ankole and Teso sub-regions. Sub-region Phytochemical quantity, milligram per gram of dry weight of the vegetable sample (mg/g d.wt) Total phenolic content Total tannin content Total flavonoid content Total Saponin content Total alkaloid content Ankole 27.6 ± 6.09 20.1 ± 9.28 43.4 ± 6.79 67.0 ± 30.20 79.1 ± 19.60 Teso 28.2 ± 7.16 34.7 ± 16.60 40.8 ± 0.62 133.3 ± 31.90 78.5 ± 43.30 p-value 0.83 0.02* 0.20 0.000* 0.96 Note: p-values less than 0.05 are statistically significant (bold value*). 424 ASEKENYE ET AL. 25735098, 2025, 12, D ow nloaded from https://scijournals.onlinelibrary.w iley.com /doi/10.1002/jsf2.70018 by M akerere U niversity, W iley O nline L ibrary on [19/03/2026]. See the T erm s and C onditions (https://onlinelibrary.w iley.com /term s-and-conditions) on W iley O nline L ibrary for rules of use; O A articles are governed by the applicable C reative C om m ons L icense differently, since they grow in different environmental conditions (soil and climate). Therefore, when eaten, there would be a difference in the degree of reduction of blood sugars in the consumers, and hence the dif- ference the in prevalence of hyperglycemia in the two study sub-regions. Physical and chemical properties of soil samples from Ankole and Teso sub-regions of Uganda and phytochemical composition of A. dubius Biological activities of plants are a reflection of phytochemicals in them, and these phytochemicals are in turn greatly influenced by the environmental conditions in which plants grow. Physical soil proper- ties provide retention, solubility, and availability of the soil chemical nutrients, and once the latter is absorbed by the plant, it is internally traded off to dictate the carbon–nitrogen balance, which also influ- ences the synthesis and the accumulation of phytochemicals. In this study, the average pH of soil samples from Teso sub-region is neutral and it is in the alkaline-neutral range (6.2–7.7). This range was different from the one reported by Gachimbi and Maritima,94 which was extremely acidic (4.5–6.5). Soil pH from Ankole sub-region was in an acidic-neutral range (6.3–6.6), and the difference in soil pH from these sub-regions was significant. It has been reported that soil pH is greatly influenced by the acid-forming cations (H+, Al3+, F2+/3+) and the base-forming cations (Ca2+, Mg2+, Na+, K+) in the soil. Due to the relatively lower precipitation in Teso sub-region, there is little leaching of the base cations, resulting in a relatively high degree of their saturation and hence the alkaline pH,95 recorded in soil samples from Teso sub-region. This alkaline pH could be responsible for the solubility of organic carbon in the soil, which was then absorbed by the plant for the synthesis of carbon-based phytochemicals– polyphe- nolic compounds (TTC and TPC), that were significantly higher in A. dubius samples in Teso sub-region. These phytochemicals are reported to lower blood sugar via various mechanisms of action, for example, free radical scavenging,96–98 hence the lower prevalence of hyperglycemia reported in Teso sub-region. Our results show that OM percentage is higher in the soil samples from Teso sub-region; however, the organically bound nutrients (N and P) are instead higher in the soil samples from Ankole sub- region. This irony could mean that the soil samples from Ankole sub- region contain OM in the active pool, that is, still being decomposed by microorganisms, thereby releasing the organically bound nutrients. Contrary to the samples from Teso sub-region, although its OM per- centage is significantly higher, it is in the slow and passive pool, which is mainly detritus and partially resistant to microbial decomposition, consequently releasing less organically bound nutrients.99 T AB L E 4 Phytochemical quantities (mean ± standard deviation) in aqueous leaf extracts of Amaranthus dubius samples from the study districts. Phytochemical quantity (mg/g d.wt) Rubirizi Ibanda Ntungamo Kiruhura Katakwi Kaberamaido Soroti Ngora Total phenolic content (TPC) 20.9 ± 3.71b* 29.4 ± 2.51ab 25.2 ± 3.09ab 34.9 ± 3.84a* 22.9 ± 7.93ab 23.7 ± 2.98ab 31.9 ± 7.12ab 34.3 ± 3.06a Total tannin content (TTC) 21.1 ± 4.94bc 11.5 ± 2.94c* 15.5 ± 7.94c 32.4 ± 2.64b 18.7 ± 0.92bc 29.4 ± 2.10b 30.4 ± 10b 60.2 ± 8.82a* Total flavonoid content (TFC) 42.6 ± 3.16a 41.2 ± 1.84a 48.3 ± 13.80a 41.7 ± 0.14a 40.5 ± 0.28a 41.2 ± 0.28a 41.5 ± 0.1a 40.1 ± 0.24a Total saponin content (TSC) 37.9 ± 3.99b* 59.5 ± 24.50b 80.9 ± 24.40ab 89.6 ± 37.10ab 135.7 ± 29.70a 145.1 ± 18.10a 152.5 ± 42.40a* 99.7 ± 11.62ab Total alkaloid content (TAC) 65.4 ± 18.40bc 68.4 ± 12.35bc 105.1 ± 10.58ab 77.7 ± 6.61ab 22.8 ± 6.1c* 126.5 ± 6.10a* 83.7 ± 7.54ab 81.0 ± 6.55ab Note: Values in the same row that do not share a letter are significantly different, bold value and * = p < 0.05. T AB L E 5 Pearson’s correlation coefficients between soil properties and phytochemicals quantities in Amaranthus dubius samples. Phytochemical pH % Mgkg�1 Cmol/kg Mgkg�1 % OM N Av. P K+ Na Ca2+ Mg2+ Fe Sand Clay Silt Total phenol content 0.18 ns 0.28 ns �0.06 ns �0.13 ns 0.07 ns 0.24 ns 0.09 ns �0.32 ns �0.32 ns 0.27 ns 0.11 ns �0.20 ns Total tannin content 0.58* 0.25 ns 0.30 ns �0.14 ns �0.05 ns 0.26 ns 0.33 ns �0.17 ns �0.09 ns 0.31 ns �0.17 ns �0.06 ns Total flavonoid content �0.18 ns �0.10 ns �0.18 ns 0.07 ns 0.59** 0.5** 0.09 ns 0.63** 0.52** �0.38 ns 0.12 ns 0.43* Total saponin content 0.22 ns 0.45* 0.62** �0.49* �0.31 ns 0.05 ns 0.11 ns �0.01 ns 0.01 ns 0.52** �0.30 ns �0.57** Total alkaloid content �0.18 ns 0.01 ns 0.42* �0.03 ns 0.11 ns 0.28 ns �0.01 ns 0.18 ns 0.18 ns �0.43* 0.25 ns 0.12 ns Note: (� values) = negative correlation; (+ values) positive correlation; ns = not significant (p > 0.05); bold value* = significant (p < 0.05); ** = highly significant (p < 0.05). SOIL PROPERTIES AND PHYTOCHEMICAL ANALYSIS 425 25735098, 2025, 12, D ow nloaded from https://scijournals.onlinelibrary.w iley.com /doi/10.1002/jsf2.70018 by M akerere U niversity, W iley O nline L ibrary on [19/03/2026]. See the T erm s and C onditions (https://onlinelibrary.w iley.com /term s-and-conditions) on W iley O nline L ibrary for rules of use; O A articles are governed by the applicable C reative C om m ons L icense Furthermore, naturally, the accumulation of soil OM is inversely related to altitude. Ankole sub-region is at a higher altitude (1806 m) compared to Teso sub-region (1129 m); this justifies the less OM per- centage in the soil samples from Ankole sub-region because low tem- peratures in higher altitudes impair plant growth and therefore result in less plant residue.100 Consequently, N and P are released from the soil OM for the plant for the synthesis of the nitrogen-based phytochemicals—alkaloids, that were highly quantified in the vegeta- ble samples from Ankole sub-region. This phytochemical class is not as implicated in the reduction of blood sugars as the phenolic class, and therefore, also not as beneficial in the reduction of blood sugar, and it led to a higher prevalence of hyperglycemia in the residents of Ankole sub-region. Silt, on the other hand, tends to increase with altitude,101 and this concept concurs with our results that show a higher silt percentage in soil samples from the Ankole sub-region, which is at a relatively higher altitude compared to the Teso sub-region. According to the soil textural triangle, the soil textural class for soil samples from Ankole sub-region is sandy clay loam, whereas that from Teso sub-region is sandy loam. Epeju and Rukundo, and the Uganda Investment Authority,102,103 reported the same soil textural class from Teso sub-region. Muzira et al.104 also confirm our findings on the textural class of the soils in Ankole sub-region. These classes arise from the significantly different percentages of sand, clay, and silt in the soil samples from these sub-regions. The clay component in the soil improves its nutrient retention ability, whereby the latter are available for plant growth and secondary metabolism. Phytochemical quantity in aqueous extracts of A. dubius from the Ankole to Teso sub-region in Uganda Reports on the health benefits of vegetables in the genus Amaranthus indicate that it is rich in anti-oxidant properties due to the phenolic compounds found in it.22,96 We quantified TPC, TTC, TSC, TFC and TAC in A. dubius samples from Ankole and Teso sub-regions, and TTC and TSC were found to be significantly different in the study sub- regions. TFC and TAC were higher in the Ankole sub-region, whereas TPC was higher in the Teso sub-region, though the difference was not significant. The average quantity of TPC in A. dubius in both study sub-regions was 28 mg GAE/g d.wt. This quantity was higher than that in other Amaranthus species studied by other researchers. For example, A. spinosus contained 25.7 μg GAE/100 g fresh weight (fr.wt), and A. viridis contained 43.4 μg GAE/100 g fr.wt, as quantified by Sarker and Oba.105 Likewise, the average TFC we quantified in A. dubius samples was less than that in A. viridis (43 μg GAE/100 g d. wt) and in A. spinosus (177.6 and 176.1 μg GAE/100 g fr. wt), respec- tively. All three species, that is, A. dubius, A. viridis, and A. spinosus, are reported to contain less phytochemical quantities compared to the popular drought-resistant A. tricolor, which was reported to contain 184 and 335.5 μg/g fr.wt of TPC and TFC, respectively.106 The differ- ence is probably due to the influence of the adverse drought conditions on A. tricolor’s phytochemical synthesis to protect itself. When we further compared our results from A. dubius to those from the other frequently eaten leafy vegetable species (Hibiscus sabdariffa, Solanum nigrium, and Vigna unguiculata) in the same study sub- regions,107 we recorded higher quantities of TPC, TFC, and TTC, that is, 66, 49, and 112 mg/g, respectively, in Hibiscus sabdariffa leaf extract. Tsado et al.108 also extracted even higher quantities in H. sabdariffa with the methanol solvent, that is, 51.9, 102.6, 54.8, 67.5, and 121.5 mg/g of TTC, TSC, TAC, TFC, and TPC, respectively. Solanum nigrium also contained higher quantities of all these phyto- chemicals in the aqueous extract, that is, 50, 172, 71, 119, and 81 mg/g of TPC, TTC, TFC, TAC, and TSC, respectively. In Vigna unguiculata, its aqueous extract also contained higher TPC, TTC, TFC, and TSC (64, 103, 66, and 126 mg/g, respectively), but lower TAC (45 mg/g). Conversely, Pioltelli et al.109 quantified very low (0.77 mg/g) amount of TPC in V. unguiculata with the same solvent. These differences in the vegetable phytochemical quantities could be due to the influence of environmental conditions (soil and climate), veg- etable species, and extraction conditions. Therefore, residents of sub- regions whose climate and soil properties favor the synthesis of phyto- chemicals, consume the phytochemically-rich vegetables, thereby benefiting from their biological effects (e.g., reduction in blood sugar levels), and reduced prevalence of hyperglycemia in the sub-region.107 Relationship between the phytochemical quantities in Amaranthus dubius and physico-chemical properties of soil from the Ankole and Teso sub-regions Results from our study show a linear relationship (in both directions) between phytochemical quantities in A. dubius and soil properties from the study sub-regions, and some of these relationships are signif- icant. The quantity of TPC, TFC, and TAC in the samples of A. dubius from Ankole and Teso sub-regions was not significantly different. However, the quantity of TTC and TSC was significantly different in both study sub-regions. TTC and TSC are positively correlated with soil pH, and the relationship with TTC was significant. Acidic soils are reported to promote nitrification and carbon substrate utilization, which is characterized by vegetation that produces polyphenolic phy- tochemicals.36 This concept is not in accord with our results, which show increasing TTC and TSC with alkaline soils in the Teso sub- region. The negative correlation between TPC and TFC in A. dubius, and N in the soil can be explained by the activation of carbon-based phytochemical genes in the plant to produce phenolic compounds. This concept is supported by the carbon/nitrogen balance (CNB) hypothesis.42 Stewart et al.43 observed similar results in tomato seed- lings, that is, the concentration of phenolic compounds (quercetin and kaempferol) was decreased in response to an increase in nitrogen fer- tilizer application. On the other hand, the positive relationship between N in the soil and TAC in the vegetable agrees with CNB the- ory, which states that increased N nutrients promote the synthesis of N-based phytochemicals like alkaloids. TPC and TFC were also noted to positively correlate with clay percentage in the soil, and higher clay 426 ASEKENYE ET AL. 25735098, 2025, 12, D ow nloaded from https://scijournals.onlinelibrary.w iley.com /doi/10.1002/jsf2.70018 by M akerere U niversity, W iley O nline L ibrary on [19/03/2026]. See the T erm s and C onditions (https://onlinelibrary.w iley.com /term s-and-conditions) on W iley O nline L ibrary for rules of use; O A articles are governed by the applicable C reative C om m ons L icense content in the soil was reported to support the accumulation of phe- nolic compounds in Iris species.33 Salinity stress is another soil abiotic factor caused by excessive salt ions (Na+, Ca2+, Mg2+, K+) in the soil. This condition leads to the accumulation of ROS in the plant, which then induces the production of antioxidant compounds like flavo- noids. TFC was higher in A. dubius from the Ankole sub-region, and soil samples from this sub-region contained higher Na+, K+, and Mg2+ concentrations. This relationship between salinity stress and flavonoid phytochemicals was observed by several researchers56,105,110 in their studies. The correlation coefficients in our results were medium, and it could be due to the influence of other environmental factors like tem- perature, soil water, and altitude on the relationship between the veg- etable phytochemicals in A. dubius and soil properties. Although we did not specifically evaluate these factors, there is documented evi- dence of their influence on plant phytochemicals. TTC and TSC are both significantly higher in vegetable samples from the Teso sub- region. Knowing that the average annual temperature in the Teso sub-region is higher (25�C) than that (17.2�C) in the Ankole sub- region, the significant difference in the quantity of TTC and TSC in both study sub-regions is not surprising. The above-reported influ- ence of temperature was also reported by Bezruk et al.27 who found out that growing Hedera helix in a warm climate (average of 22�C) does support the accumulation of phenolic components in the leaves. Drought stress from insufficient water in the soil can impair plant growth and induce phytochemical synthesis. The average annual rain- fall in the Teso sub-region (1000 mm) is less than that in the Ankole sub-region (1018 mm). A. dubius vegetable samples from the Teso sub-region likely suffered water stress that induced the synthesis of polyphenolic phytochemicals like TTC. This finding is corroborative with those from Sarker et al.’s study on drought-resistant A. tricolor species that contained higher quantities of polyphenols.106 CONCLUSION Indeed, the phytochemical quantity in a plant does vary depending on geographical location. In this study, we observed the influence of soil properties from different sub-regions on the A. dubius phytochemicals. Soils higher in cations, pH, and sand percentage do support the syn- thesis of polyphenolic compounds (TTC, TPC, and TSC) in the plants. Also, other climatic conditions like higher temperatures, salinity stress, and low precipitation induce the production of the above phytochemi- cals. Therefore, to enhance and expedite the production of these phy- tochemicals in vegetables, the above soil and climatic conditions should be guaranteed. ACKNOWLEDGMENTS This research was supported by The Pharm-Biotechnology and Tradi- tional Medicine Centre (PHARMBIOTRAC) program with financial support from the World Bank to Eastern and Southern Africa Higher Education Centers of Excellence (ACE II) Program at Mbarara Univer- sity of Science and Technology. CONFLICT OF INTEREST STATEMENT The authors declare no conflict of interest. DATA AVAILABILITY STATEMENT The datasets used and/or analyzed during the current study are avail- able from the corresponding author on reasonable request. ETHICS STATEMENT The study was approved by Mbarara University of Science and Technol- ogy Research Ethics Committee (MUST-REC) under Protocol number MUST-2021-52 and registered with the Uganda National Council for Science and Technology (UNCST) under registration number HS1840ES. ORCID Caroline Asekenye https://orcid.org/0009-0007-7218-2738 REFERENCES 1. Saeedi P, Petersohn I, Salpea P, Malanda B, Karuranga S, Unwin N, et al. Global and regional diabetes prevalence estimates for 2019 and projections for 2030 and 2045: results from the International Diabe- tes Federation Diabetes Atlas, 9th edition. Diabetes Res Clin Pract. 2019;157:107843. 2. Cho NH, Shaw JE, Karuranga S, Huang Y, da Rocha Fernandes JD, Ohlrogge AW, et al. IDF diabetes atlas: global estimates of diabetes prevalence for 2017 and projections for 2045. Diabetes Res Clin Pract. 2018;138(Apr 1):271–81. 3. Asekenye C, Alele PE, Ogwang PE, Olet EA. Frequency of consump- tion of green leafy vegetables and prevalence of hyperglycaemia in Ankole and Teso sub-regions of Uganda. J Clin Transl Res. 2023;9(6): 398–413. 4. Bahendeka S, Wesonga R, Mutungi G, Muwonge J, Neema S, Guwatudde D. Prevalence and correlates of diabetes mellitus in Uganda: a population-based national survey. Trop Med Int Health. 2016;21(3):405–16. 5. Kabwama SN, Bahendeka SK, Wesonga R, Mutungi G, Guwatudde D. Low consumption of fruits and vegetables among adults in Uganda: findings from a countrywide cross-sectional sur- vey. Arch Public Health. 2019;77(1):4–11. 6. Nuwagira U, Yasin I. Review of the past, current, and the future trend of the climate change and its impact in Uganda. East Afr J Environ Nat Resour. 2022;5(1):115–26. 7. Nsubuga FW, Rautenbach H. Climate change and variability: a review of what is known and ought to be known for Uganda. Int J Clim Chang Strateg Manag. 2018;10(5):752–71. 8. Justin K, Edmond S, Ally M, Xin H. Plant secondary metabolites: bio- synthesis, classification, function and pharmacological properties. J Pharm Pharmacol. 2014;2014(2):377–92. 9. Bennett RN, Wallsgrove RM. Secondary metabolites in plant defence mechanisms. New Phytol. 1994;127(4):617–33. 10. Biesiada A, Tomczak A. Biotic and abiotic factors affecting the con- tent of the chosen antioxidant compounds in vegetables. Veg Crop Res Bull. 2012;76(1):55–78. 11. Wink M. Evolution of secondary metabolites from an ecological and molecular phylogenetic perspective. Phytochemistry. 2003;64:3–19. 12. Rastogi A, Shukla S. Amaranth: a new millennium crop of nutraceuti- cal values. Crit Rev Food Sci Nutr. 2013;53(2):109–25. 13. Assad R, Reshi ZA, Jan S, Rashid I. Biology of amaranths. Bot Rev. 2017;83:382–436. 14. Joshi N, Verma KC. A review on nutrition value of Amaranth (Amaranthus caudatus L.): the crop of future. J Pharmacogn Phyto- chem. 2020;9(4):317–9. SOIL PROPERTIES AND PHYTOCHEMICAL ANALYSIS 427 25735098, 2025, 12, D ow nloaded from https://scijournals.onlinelibrary.w iley.com /doi/10.1002/jsf2.70018 by M akerere U niversity, W iley O nline L ibrary on [19/03/2026]. See the T erm s and C onditions (https://onlinelibrary.w iley.com /term s-and-conditions) on W iley O nline L ibrary for rules of use; O A articles are governed by the applicable C reative C om m ons L icense https://orcid.org/0009-0007-7218-2738 https://orcid.org/0009-0007-7218-2738 15. Kauffman CS. Realizing the potential of grain amaranth. Food Rev Int. 1992;8(1):5–21. 16. Jimoh MO, Afolayan AJ, Lewu FB. Suitability of Amaranthus species for alleviating human dietary deficiencies. S Afr J Bot. 2018;115:65–73. 17. Ruth ON, Unathi K, Nomali N, Chinsamy M. Underutilization versus nutritional-nutraceutical potential of the amaranthus food plant: a mini-review. Appl Sci. 2021;11(15):6879. 18. Ramdwar MN, Chadee ST, Stoute VA. Estimating the potential con- sumption level of amaranth for food security initiatives in Trinidad, West Indies. Cogent Food Agric. 2017;3(1):1321475. 19. Srivastava R. Nutritional quality of some cultivated and wild species of Amaranthus L. Int J Pharm Sci Res. 2011;2(12):3152. 20. Sarker U, Oba S. Nutraceuticals, antioxidant pigments, and phyto- chemicals in the leaves of Amaranthus spinosus and Amaranthus viri- dis weedy species. Sci Rep. 2019;9(1):20413. 21. Sarker U, Oba S. Protein, dietary fiber, minerals, antioxidant pigments and phytochemicals, and antioxidant activity in selected red morph Amaranthus leafy vegetable. PLoS One. 2019;14(12):1–16. 22. Yang YC, Mong MC, Wu WT, Wang ZH, Yin MC. Phytochemical pro- files and anti-diabetic benefits of two edible Amaranthus species. CyTA. 2020;18(1):94–101. 23. Ogwu MC, Izah SC, Joshua MT. Ecological and environmental deter- minants of phytochemical variability in forest trees. Phytochem Rev. 2025; 2025:1–29. 24. Liebelt DJ, Jordan JT, Doherty CJ. Only a matter of time: the impact of daily and seasonal rhythms on phytochemicals. Phytochem Rev. 2019;18:1409–33. 25. Borges CV, Junior SS, Ponce FS, Lima GPP. Agronomic factors influencing brassica productivity and phytochemical quality, in Bras- sica germplasm - characterization, breeding and utilization, ed. by Mohamed A. El-Esawi, London: IntechOpen; 2018. 26. Putra RP, Mediartha IK, Setiawan MAD, Sujai PAN, Arista RA, Kandi RP, et al. Effects of NPK fertilizer on growth, phytochemical content and antioxidant activity of purslane (Portulaca grandiflora). Curr Appl Sci Technol. 2023;24:e0257237. 27. Bezruk I, Materiienko A, Gubar S, Proskurina K, Budanova L, Ivanauskas L, et al. Estimation of the influence of the environmental factors on the accumulation of phytochemicals and antioxidant capacity in the ivy leaves (Hedera helix L.). Nat Prod Res. 2022;36(4): 1014–9. 28. Mudau HS, Mokoboki HK, Ravhuhali KE, Mkhize Z. Effect of soil type: qualitative and quantitative analysis of phytochemicals in some browse species leaves found in Savannah biome of South Africa. Molecules. 2022;27(5):1462. 29. Oh M-M, Trick HN, Rajashekar CB. Secondary metabolism and anti- oxidants are involved in environmental adaptation and stress toler- ance in lettuce. J Plant Physiol. 2009;166(2):180–91. 30. Nørbæk R, Aaboer DBF, Bleeg IS, Christensen BT, Kondo T, Brandt K. Flavone C-glycoside, phenolic acid, and nitrogen contents in leaves of barley subject to organic fertilization treatments. J Agric Food Chem. 2003;51(3):809–13. 31. Łata B, Agrophysica MW-K-A. U. Chemical composition of kale culti- vated on two types of soil. 2006 acta-agrophysica.org 32. Wang SY, Lin HS. Compost as a soil supplement increases the level of antioxidant compounds and oxygen radical absorbance capacity in strawberries. J Agric Food Chem. 2003;51(23):6844–50. 33. Mykhailenko O, Gudžinskas Z, Kovalyov V, Desenko V, Ivanauskas L, Bezruk I, et al. Effect of ecological factors on the accumulation of phenolic compounds in Iris species from Latvia, Lithuania and Ukraine. Phytochem Anal. 2020;31(5):545–63. 34. Bones AM, Rossiter JT. The enzymic and chemically induced decom- position of glucosinolates. Phytochemistry. 2006;67(11):1053–67. 35. Borek V, Morra MJ, Brown PD, McCaffrey JP. Allelochemicals pro- duced during sinigrin decomposition in soil. J Agric Food Chem. 1994;42(4):1030–4. 36. Yao H, Campbell CD, Qiao X. Soil pH controls nitrification and car- bon substrate utilization more than urea or charcoal in some highly acidic soils. Biol Fertil Soils. 2011;47(5):515–22. 37. Antonious GF. The impact of organic, inorganic fertilizers, and bio- char on phytochemicals content of three Brassicaceae vegetables. Appl Sci. 2023;13(15):8801. 38. Siddiqui Y, Munusamy U, Naidu Y, Ahmad K. Integrated effect of plant growth-promoting compost and NPK fertilizer on nutrient uptake, phenolic content, and antioxidant properties of Orthosiphon stamineus and Cosmos caudatus. Hortic Environ Biotechnol. 2020; 61(6):1051–62. 39. Chibueze U, Akubugwo E. Nutritive values and phytochemical con- tents of some leafy vegetables grown with different fertilizers. Agric Biol J North Am. 2011;2(12):1437–44. 40. Yang L, Wen KS, Ruan X, Zhao YX, Wei F, Wang Q. Response of plant secondary metabolites to environmental factors. Mol. 2018; 23:762. 41. Schreiner M. Vegetable crop management strategies to increase the quantity of phytochemicals. Eur J Nutr. 2005;44(2):85–94. 42. Hamilton JG, Zangerl AR, DeLucia EH, Berenbaum MR. The carbon- nutrient balance hypothesis: its rise and fall. Ecol Lett. 2001;4(1): 86–95. 43. Stewart AJ, Chapman W, Jenkins GI, Graham I, Martin T, Crozier A. The effect of nitrogen and phosphorus deficiency on flavonol accu- mulation in plant tissues. Plant Cell Environ. 2001;24(11):1189–97. 44. Bourn D, Prescott J. A comparison of the nutritional value, sensory qualities, and food safety of organically and conventionally produced foods. Crit Rev Food Sci Nutr. 2002;42(1):1–34. 45. Dixon RA, Paiva NL. Stress-induced phenylpropanoid metabolism. Plant Cell. 1995;7(7):1085. 46. Barlóg P. Effect of magnesium and nitrogenous fertilisers on the growth and alkaloid content in Lupinus angustifolius L. Aust J Agr Res. 2002;53(6):671–6. 47. Ciesiołka D, Muzquiz M, Burbano C, Altares P, Pedrosa MM, Wysocki W, et al. An effect of various nitrogen forms used as fertil- izer on Lupinus albus L. yield and protein, alkaloid and α-galactosides content. J Agron Crop Sci. 2005;191(6):458–63. 48. Al-Humaid AI. Effects of compound fertilization on growth and alka- loids of Datura plants. J Plant Nutr. 2005;27(12):2203–19. 49. Lerdau M, Matson P, Fall R, Monson R. Ecological controls over monoterpene emissions from douglas-fir (Pseudotsuga menziesii). Ecology. 1995;76(8):2640–7. 50. Burney OT, Davis AS, Jacobs DF. Phenology of foliar and volatile ter- penoid production for Thuja plicata families under differential nutri- ent availability. Environ Exp Bot. 2012;77:44–52. 51. Bedel L, Legout A, Poszwa A, van Der Heijden G, Court M, Goutal- Pousse N, et al. Soil aggregation may be a relevant indicator of nutri- ent cation availability. Ann For Sci. 2018;75:1–12. 52. Khaledian Y, Brevik EC, Pereira P, Cerdà A, Fattah MA, Tazikeh H. Modeling soil cation exchange capacity in multiple countries. Catena. 2017;158:194–200. 53. Munns R, Tester M. Mechanisms of salinity tolerance. Annu Rev Plant Biol. 2008;59:651–81. 54. Menezes-Benavente L, Kernodle SP, Margis-Pinheiro M, Scandalios JG. Salt-induced antioxidant metabolism defenses in maize (Zea mays L.) seedlings. Redox Rep. 2013;9(1):29–36. 55. Parida AK, Das AB, Sanada Y, Mohanty P. Effects of salinity on bio- chemical components of the mangrove, Aegiceras corniculatum. Aquat Bot. 2004;80(2):77–87. 56. Tounekti T, Vadel A m, Ennajeh M, Khemira H, Munné-Bosch S. Ionic interactions and salinity affect monoterpene and phenolic diterpene composition in rosemary (Rosmarinus officinalis). J Plant Nutr Soil Sci. 2011;174(3):504–14. 57. Knowles O, Dawson A. Current soil sampling methods – a review. Farm Environ Plan Sci Policy Pract. 2018;31:1–11. 428 ASEKENYE ET AL. 25735098, 2025, 12, D ow nloaded from https://scijournals.onlinelibrary.w iley.com /doi/10.1002/jsf2.70018 by M akerere U niversity, W iley O nline L ibrary on [19/03/2026]. See the T erm s and C onditions (https://onlinelibrary.w iley.com /term s-and-conditions) on W iley O nline L ibrary for rules of use; O A articles are governed by the applicable C reative C om m ons L icense http://acta-agrophysica.org 58. Edwards AC. Soil sampling and sample preparation. Trace Elem soils. Oxford, United Kingdom: Blackwell Publishing Ltd; 2010. p. 39–51. 59. Wulfsohn D. Sampling techniques for plants and soil. Landbauforsch Volkenrode. 2010; 2010:(Special Issue 340):3–30. 60. Jones J. Soil analysis handbook of reference methods. Boca Raton: CRC press; 2018. 61. Pal SK. Soil sampling and methods of analysis. Delhi, India: New India Publishing; 2013. 62. Boroomand N, Grouh MSH. Macro elements nutrition (NPK) of medicinal plants. J Med Plant Res. 2012;6(12):2249–55. 63. Elser JJ, Bracken MES, Cleland EE, Gruner DS, Harpole WS, Hillebrand H, et al. Global analysis of nitrogen and phosphorus limita- tion of primary producers in freshwater, marine and terrestrial eco- systems. Ecol Lett. 2007;10(12):1135–42. 64. Kant S, Peng M, Rothstein SJ. Genetic regulation by NLA and micro- RNA827 for maintaining nitrate-dependent phosphate homeostasis in Arabidopsis. PLoS Genet. 2011;7(3):e1002021. 65. Martins-Noguerol R, Matías L, Pérez-Ramos IM, Moreira X, Francisco M, Pedroche J, et al. Soil physicochemical properties associ- ated with the yield and phytochemical composition of the edible halo- phyte Crithmum maritimum. Sci Total Environ. 2023;869:161806. 66. Ondrasek G, Rengel Z. Environmental salinization processes: detec- tion, implications & solutions. Sci Total Environ. 2021;754:142432. 67. Acharya SM. Collection and preparation of soil, water and plant sam- ples for analysis. Int J Chem Stud. 2018;6(2):3298–303. 68. Miller RO, Kissel DE. Comparison of soil pH methods on soils of North America. Soil Sci Soc Am J. 2010;74(1):310–6. 69. Thunjai T, Boyd CE, Dube K. Poind soil pH measurement. J World Aquac Soc. 2001;32(2):141–52. 70. Sumner ME. Measurement of soil pH: problems and solutions. Com- mun Soil Sci Plant Anal. 1994;25(7–8):859–79. 71. Shamrikova EV, Kondratenok BM, Tumanova EA, Vanchikova EV, Lapteva EM, Zonova TV, et al. Transferability between soil organic matter measurement methods for database harmonization. Geo- derma. 2022;412:115547. 72. Shamrikova EV, Vanchikova EV, Kondratenok BM, Lapteva EM, Kostrova SN. Problems and limitations of the dichromatometric method for measuring soil organic matter content: a review. Eurasian Soil Sci. 2022;55(7):861–7. 73. Strosser E. Methods for determination of labile soil organic matter: an overview. J Agrobiol. 2010;27(2):49–60. 74. Mwendwa S. Revisiting soil texture analysis: practices towards a more accurate Bouyoucos method. Heliyon. 2022;8(5):e09395. 75. Mwendwa S. The Mwendwa Protocol: A modification of the Bouyoucos method of soil texture analysis. 2020. 76. Beretta AN, Silbermann AV, Paladino L, Torres D, Kassahun D, Musselli R, et al. Soil texture analyses using a hydrometer: modifica- tion of the Bouyoucos method. Cienc e Investig Agrar Rev Latinoam Ciencias la Agric. 2014;41(2):263–71. 77. Thomas EY, Omueti JAI, Akpan IO. Macro and micro nutrients status of selected soils based on land use in Southwest, Nigeria. 2016. 78. Wang JJ, Harrell DL, Henderson RE, Bell PF. Comparison of soil-test extractants for phosphorus, potassium, calcium, magnesium, sodium, zinc, copper, manganese, and iron in Louisiana soils. Commun Soil Sci Plant Anal. 2004;35(1–2):145–60. 79. Murphy J, Riley JP. A modified single solution method for the deter- mination of phosphate in natural waters. Anal Chim Acta. 1962;27: 31–6. 80. Hood-Nowotny R, Umana NH-N, Inselbacher E, Oswald- Lachouani P, Wanek W. Alternative methods for measuring inor- ganic, organic, and total dissolved nitrogen in soil. Soil Sci Soc Am J. 2010;74(3):1018–27. 81. Okalebo JR, Gathua KW, Woomer PL. Laboratory methods of soil and plant analysis: a working manual second edition. Vol 21. Nairobi, Kenya: TSBF-CIAT and SACRED Africa; 2002. p. 25–6. 82. Azwanida NN. A review on the extraction methods use in medicinal plants, principle, strength and limitation. Med Aromat Plants. 2015; 4(196):412–2167. 83. Khan MS, Yusufzai SK, Rafatullah M, Sarjadi MS, Razlan M. Determi- nation of total phenolic content, total flavonoid content and antioxi- dant activity of various organic crude extracts of Licuala spinosa leaves from Sabah, Malaysia. ASM Sci J. 2018;11(3):53–8. 84. Baba SA, Malik SA. Determination of total phenolic and flavonoid content, antimicrobial and antioxidant activity of a root extract of Arisaema jacquemontii Blume. J Taibah Univ Sci. 2015;9(4):449–54. 85. Le AV, Parks SE, Nguyen MH, Roach PH. Improving the vanillin- Sulphuric acid method for quantifying total Saponins. Technologies. 2018;6(3):1–12. 86. Jain D, Shrivastava S. Estimation of total phenolic, flavonoid and Saponin content in different extracts of Butea monosperma bark. Int J Eng Technol Sci Res. 2017;4(7):177–82. 87. Rover MR, Brown RC. Quantification of total phenols in bio-oil using the Folin–Ciocalteu method. J Anal Appl Pyrolysis. 2013;104: 366–71. 88. De Beer D, Harbertson JF, Kilmartin PA, Roginsky V, Barsukova T, Adams DO, et al. Phenolics: a comparison of diverse analytical methods. Am J Enol Vitic. 2004;55(4):389–400. 89. Palacios CE, Nagai A, Torres P, Rodrigues JA, Salatino A. Contents of tannins of cultivars of sorghum cultivated in Brazil, as determined by four quantification methods. Food Chem. 2021;337:127970. 90. Perumalla S, Nayeem N. Determination of total phenolic acids, con- densed tannins and flavonoids in the leaves of Caesalpinia pulcher- rima Linn. Int J Phyther Res. 2012;2(3):16–9. 91. Valieva AI, Akulov AN. Application of Bromocresol green for spectro- photometric determination of alkaloid content using the example of Ruta graveolens. Russ J Plant Physiol. 2024;71(1):33. 92. Jatav P, Tenguria RK. Determination of total alkaloids and tannins contents in leaves of Buchanania Lanzan. J Coast Life Med. 2022;10: 693–700. 93. Shamsa F, Monsef H, Ghamooshi R, Verdian-rizi M. Spectrophoto- metric determination of total alkaloids in some Iranian medicinal plants. Thai J Pharm Sci. 2008;32(1):17–20. 94. Gachimbi LN, Maitima J. Soil fertility analysis associated to land use in Eastern Uganda. 2004. 95. Phares CA, Atiah K, Frimpong KA, Danquah A, Asare AT, Aggor- Woananu S. Application of biochar and inorganic phosphorus fertil- izer influenced rhizosphere soil characteristics, nodule formation and phytoconstituents of cowpea grown on tropical soil. Heliyon. 2020; 6(10):e05255. 96. Sarker U, Oba S, Ercisli S, Assouguem A. Bioactive phytochemicals and quenching activity of radicals in selected drought-resistant amar- anthus tricolor vegetable amaranth. Antioxidants. 2022;27(9):2899. mdpi.com 97. Bang JH, Lee KJ, Jeong WT, Han S, Jo IH, Choi SH, et al. Antioxidant activity and phytochemical content of nine amaranthus species. Agron. 2021;11(6):1–12. 98. Sarker U, Oba S. Phenolic profiles and antioxidant activities in selected drought-tolerant leafy vegetable amaranth. Sci Rep. 2020; 10(1):1–11. 99. Hossain MI. Correlations of available phosphorus and potassium with pH and organic matter content in the different forested soils of Chit- tagong Hill tracts, Bangladesh. Int J For Soil Eros. 2014;4(1):7–10. 100. Bromley P. The effect of elevation gain on soil. Environ Stud. 1995; 102:778–82. 101. Kidanemariam A, Gebrekidan H,Mamo T, Kibret K. Impact of altitude and land use type on some physical and chemical properties of acidic soils in Tsegede highlands, northern Ethiopia. Open J Soil Sci. 2012;2(3):223. 102. Epeju WF, Rukundo PM. Food security and income through sweet potato production in Teso, Uganda. Sustain Agric Res. 2017; 7(1):146. SOIL PROPERTIES AND PHYTOCHEMICAL ANALYSIS 429 25735098, 2025, 12, D ow nloaded from https://scijournals.onlinelibrary.w iley.com /doi/10.1002/jsf2.70018 by M akerere U niversity, W iley O nline L ibrary on [19/03/2026]. See the T erm s and C onditions (https://onlinelibrary.w iley.com /term s-and-conditions) on W iley O nline L ibrary for rules of use; O A articles are governed by the applicable C reative C om m ons L icense http://mdpi.com 103. Uganda Investment Authority. Teso investment profile. Kampala, Uganda; 2016. p. 28. 104. Muzira R, Basamba T, Tenywa JS. Assessment of soil nutrients limit- ing sustainable potato production in the highlands of South-Western Uganda. OALib. 2018;5(3):1–8. 105. Sarker U, Oba S. Salinity stress enhances color parameters, bioactive leaf pigments, vitamins, polyphenols, flavonoids and antioxidant activity in selected Amaranthus leafy vegetables. J Sci Food Agric. 2019;99(5):2275–84. 106. Sarker U, Oba S, Ercisli S, Assouguem A, Alotaibi A, Ullah R. Bioactive phytochemicals and quenching activity of radicals in selected drought-resistant Amaranthus tricolor vegetable Amaranth. Antioxi- dants. 2022;11(3):578. 107. Asekenye C, Alele PE, Ogwang PE, Olet EA. Hypoglycemic effect of leafy vegetables from Ankole and Teso sub-regions of Uganda: preclinical evaluation using a high fat diet-streptozotocin model. 2024. 108. Tsado AN, Onukogu SC, Suleiman A, Mustapha A, Osuigwe EC, Dannana LW, et al. Phytochemicals, hypoglycemic and hypolipidemic effects of methanol leaf extract of Hibiscus sabdariffa in alloxan induced diabetic rats. GSC Biol Pharm Sci. 2019;8(3):70–80. 109. Pioltelli E, Sartirana C, Copetta A, Brioschi M, Labra M, Guzzetti L. Vigna unguiculata L. Walp. Leaves as a source of phytochemicals of dietary interest: optimization of ultrasound-assisted extraction and assessment of traditional consumer habits. Chem Biodivers. 2023; 20:202300797. 110. Ksouri R, Megdiche W, Debez A, Falleh H, Grignon C, Abdelly C. Salinity effects on polyphenol content and antioxidant activities in leaves of the halophyte Cakile maritima. Plant Physiol Biochem. 2007;45(3–4):244–9. How to cite this article: Asekenye C, Alele PE, Ogwang PE, Olet EA. Soil properties and phytochemical analysis of spleen amaranth (Amaranthus dubius Mart. Ex Thell.) from Ankole and Teso sub-regions of Uganda: Implications for management and prevention of hyperglycemia. JSFA Reports. 2025;5(12): 418–30. https://doi.org/10.1002/jsf2.70018 430 ASEKENYE ET AL. 25735098, 2025, 12, D ow nloaded from https://scijournals.onlinelibrary.w iley.com /doi/10.1002/jsf2.70018 by M akerere U niversity, W iley O nline L ibrary on [19/03/2026]. See the T erm s and C onditions (https://onlinelibrary.w iley.com /term s-and-conditions) on W iley O nline L ibrary for rules of use; O A articles are governed by the applicable C reative C om m ons L icense https://doi.org/10.1002/jsf2.70018 Soil properties and phytochemical analysis of spleen amaranth (Amaranthus dubius Mart. Ex Thell.) from Ankole and Teso sub‐... ABSTRACT INTRODUCTION MATERIALS AND METHODS Materials Methods Study site characteristics Soil and vegetable sample collection Laboratory analysis of soil physical and chemical properties Soil pH Organic matter (OM) Soil particle size (soil texture) analysis Analysis of soil N, Fe, available P, and exchangeable cations (Na+, Ca2+, K+, and Mg2+) Quantification of phytochemicals in A. dubius vegetable samples Total flavonoid content (TFC) Total saponin content (TSC) Total phenolic content (TPC) Total tannin content (TTC) Total alkaloid content (TAC) Statistical analysis RESULTS Physical and chemical properties of soil samples from Ankole and Teso sub‐regions of Uganda Physical and chemical properties of soil samples from the study districts Phytochemical quantities in aqueous leaf extracts of Amaranthus dubius from Ankole and Teso sub‐regions Phytochemical quantification in aqueous leaf extracts of Amaranthus dubius samples from study districts Pearson's correlation between soil properties and phytochemical quantities in A. dubius samples DISCUSSION Physical and chemical properties of soil samples from Ankole and Teso sub‐regions of Uganda and phytochemical composition o... Phytochemical quantity in aqueous extracts of A. dubius from the Ankole to Teso sub‐region in Uganda Relationship between the phytochemical quantities in Amaranthus dubius and physico‐chemical properties of soil from the Ank... CONCLUSION ACKNOWLEDGMENTS CONFLICT OF INTEREST STATEMENT DATA AVAILABILITY STATEMENT ETHICS STATEMENT ORCID REFERENCES