Browsing by Author "Adaku, Christopher"
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Item Analysis for Organochlorine Pesticide Residues in Honey from Kabale District, South-Western Uganda(American Journal of Analytical Chemistry, 2019) Ntirushize, Benon; Wasswa, John; Ntambi, Emmanuel; Adaku, ChristopherThis study was motivated by the reported accumulation of Organochlorine Pesticides (OCPs) residues in the various environmental matrices within Uganda, resulting from their use in agriculture and health sectors. This raised a concern of the likelihood of the accumulation of the OCPs residues in the honey produced within the country which would affect its purity as well as quality and consequently its competition on the world market. Sixty representative honey samples were collected from selected local beekeepers from four sampling stations in Muko sub-county, Kabale, and extracted for OCPs using a solid-phase procedure followed by a florisil column packed clean-up method and Gas Chromatography-Electron Capture Detector (GC-ECD) analysis. Confirmation of the selected samples was done using an Agilent (6890N, USA) gas chromatograph combined with a mass spectrometer. Recoveries of spiked samples ranged from 71% to 96%, except for pp-DDE (54%), with relative standard deviations from 2% to 14% in terms of repeatability, and from 4% to 17% in terms of reproducibility. Limits of quantification were from 0.003 to 0.1 mg∙kg−1. Endosulfan sulfate was the most frequently detected in 38% of the samples, followed by HexaChloroBenzene (Lindane) in 21% of the samples. Residues of DDT and their metabolites were detected in 17% of the samples. Mean concentrations of the pesticide residues detected range from ND (not detected) to 1.53 μg/Kg. The acceptable Maximum residual limits (MLRs) are 200 - 300 μg∙kg−1 fresh weight for dieldrin, 500 μg∙kg−1 for DDT and break down products, and 50 μg∙kg−1 wet weight for Lindane (WHO/FAO 2011). Results indicate that the levels of OCP residues detected in honey from the country’s South Western District of Kabale were within the acceptable limits, and hence this honey was safe for human consumption.Item Anthocyanin Profile and Antioxidant Activity of Edible Leaves of Dissotis brazzae Cogn (Melastomataceae)(Journal of Food and Nutrition Sciences, 2020) Adaku, Christopher; Skaar, Irene; Gumisiriza, Hannington; Byamukama, Robert; Jordheim, Monica; Andersen, JOyvind MoksheimAnthocyanins are colored bioactive phytochemicals in the class of flavonoids with high potential as dietary antioxidants. Demand for anthocyanins in functional food and nutraceutical industries has continued to increase over the past decades. However, sources of anthocyanins for commercial exploitation are currently limited. Tropical Africa and Uganda in particular, harbors many plant species with potential to serve as new sources of anthocyanins. In this study, the anthocyanin profile and antioxidant activity of edible leaves of Dissotis brazzae, a plant of tropical African origin, were investigated. Two known anthocyanins, (1) cyanidin 3-O-β-glucopyranoside (1.28±0.44 mg/g fr. wt.) and (2) cyanidin 3-O-α-rhamnopyranoside (1.89±0.42 mg/g fr. wt.), were isolated from D. brazzae purple leaves by a combination of chromatographic techniques. Their structures were elucidated mainly by homo- and heteronuclear NMR spectroscopy and online HPLC/UV-Vis spectroscopy. The isolated anthocyanins showed appreciable level of antioxidant activity against DPPH, with 1 (IC50=9.2±0.2 μg/ml) showing slightly higher antioxidant potency than 2 (IC50=14.0±0.6 μg/ml). However, quercetin (IC50=4.5±0.4 μg/ml) used as a reference showed a higher antioxidant activity than 1 and 2. The total anthocyanin content of D. brazzae leaves (317 mg/100g) was within the range (80 – 680 mg/100g) of anthocyanins content in most dietary sources. This is the first report of fully characterised anthocyanins from the genus Dissotis, which may be of taxonomic importance. A new dietary source of the rare cyanidin 3-O-α-rhamnopyranoside has been identified.Item Anthocyanin Profile and Antioxidant Property of Anti-asthma Flowers of Cordyline terminalis (L.) Kunth (Agavaceae)(Natural Product Communications, 2020) Adaku, Christopher; Skaar, Irene; Byamukama, Robert; Jordheim, Monica; Øyvind, M. AndersenCordyline terminalis flower is traditionally used to treat asthma and the purple color of the flower is suggestive of anthocyanins. Thepurpose of this study was to characterize and determine the antioxidant property of anthocyanins from C. terminalis purple flowers. five anthocyanins, cyanidin 3,5-di-O-β-glucopyranoside (2.6 ± 0.2 mg/g fr. wt) (1), peonidin 3,5-di- O- β-glucopyranoside (2.8 ± 0.3 mg/g fr. wt) (2), cyanidin 3-O- β-(6″-O- E- p- caffeoylglucopyranoside)- 5-O- β-glucopyranoside (3.2 ± 0.2 mg/g fr. wt) (3), cyanidin 3-O- β-(6″-O- E- p- coumaroylglucopyranoside)- 5-O- β-glucopyranoside (6.2 ± 0.4 mg/g fr. wt) (4), and peonidin 3-O- β-(6″-O- E- p- c oumaroylglucopyranoside)-5-O- β-glucopyranoside (9.8 ± 0.2 mg/g fr. wt) (5), were isolated from the flowers of C. terminalis by a combination of chromatographic techniques. Their structures were established by UV-visible, NMR, and ESI-MS. The extract exhibited appreciable antioxidant activity (IC50 ± SD = 13.1 ± 0.8 μg/mL) against quercetin (IC50 ± SD = 4.5 ± 0.4 μg/mL) compared to the individual anthocyanins (IC50 ± SD = 13.8 ± 0.5 to 16.4 ± 0.7 μg/mL) when measured using the 2,2-diphenyl- 1-picryl- hydrazyl method. Cordyline terminalis flowers extract may be justified for use and standardization as herbal remedy for asthma.Item Anthocyanins from Mauve Flowers of Erlangea tomentosa (Bothriocline longipes) Based on erlangidin – The first Reported Natural Anthocyanidin with C-ring methoxylation(Phytochemistry Letters, 2019) Adaku, Christopher; Skaar, Irene; Berland, Helge; Byamukama, Robert; Jordheim, Monica; Andersen, Øyvind M.Above 700 different anthocyanins have been isolated from plants. These flavonoid pigments are grouped after the number and position of hydroxy- and methoxy-groups on their anthocyanidin A- and B-rings, which influence their properties. In this study two new anthocyanins, erlangidin 5-O-(4″-(E-caffeoyl)-6″-(malonyl)-β-glucopyranoside)- 3′-O-(6‴-(3II-(β-glucopyranosyl)-E-caffeoyl)-β-glucopyranoside) and erlangidin 5-O-(6″-(malonyl)- β-glucopyranoside)-3′-O-(6‴-(3II-(β-glucopyranosyl)-E-caffeoyl)-β-glucopyranoside) were isolated from purple flowers of Erlangea tomentosa (Bothriocline longipes) Oliv. & Hiern (Asteraceae) in amounts of ∼1.6 and 0.6 mg/g fr. wt., respectively. They were found to contain the first reported natural anthocyanidin with a methoxy-group on the heterocyclic C-ring, which we have given the name erlangidin.” During extraction, isolation and storage in acidified methanolic solvents the two anthocyanins were both partly converted to their demalonylated and methylmalonyl esterified forms. Spectroscopic and chromatographic characteristics for erlangidin in comparison with the common anthocyanidins, which it might be mistaken for, are included.Item Physicochemical Quality and Health Risks Associated with Use of Water from Nyamwamba River, Kasese, Western Uganda(Asian Journal of Applied Chemistry Research, 2022) Masereka, Jockus; Byamugisha, Denis; Adaku, ChristopherIn Kasese district of Western Uganda, farmers cultivating near Nyamwamba River (NR) experience crop wilting whenever the river banks burst. Increased cases of cancer and ulcers in the district is anecdotally blamed on ingestion of contaminated water from water resources polluted by tailings from Kilembe copper mines. Sand miners attested that mining in NR caused body irritations and itching while drinking water from the same river results in abdominal complications in infants. The aim of this study was to assess the seasonal variations in the physicochemical parameters and heavy metals (HMs) content of water from NR, and the associated health risks.Item Pollution Status, Source Apportionment, Ecological and Human Health Risks of Potentially (Eco)toxic Element-Laden Dusts from Urban Roads, Highways and Pedestrian Bridges in Uganda(Cham: Springer International Publishing, 2021) Opolot, Mark; Omara, Timothy; Adaku, Christopher; Ntambi, EmmanuelThe occurrence of potentially (eco)toxic elements (PTEs) in street, indoor and roadside dusts have been associated with potential human health risks. For the first time, the pollution levels of PTEs—copper (Cu), nickel (Ni), manganese (Mn), zinc (Zn), lead (Pb), cadmium (Cd) and chromium (Cr)—were investigated in 24 dust samples from eight selected sampling sites on urban roads, highways and pedestrian bridges constructed over River Manafwa, a flood-prone river in Eastern Uganda. Concentration of PTEs in the sample digests were quantified by atomic absorption spectrometry. Multivariate geostatistical (Pearson’s Correlation, Principal Components and Hierarchical Cluster) analyses were used to apportion sources of the contaminants. Contamination, ecological and human health assessment indices and models were employed to establish any potential risks the elements could pose to the environment and humans. The study revealed that there is severe PTE pollution of dusts from roads, highways and pedestrian bridges in Eastern Uganda when compared with their crustal averages, except for Cu, Ni and Cr. The mean concentrations (mg kg1) of Cu (11.4–23.2), Ni (0.20–23.20), Mn (465.0–2630.0), Zn (26.8–199.0), Pb (185.0–244.0), Cd (0.178–1.994) and Cr (5.40–56.60) were highest in samples obtained near high-traffic areas. Source apportionment studies suggested that Cu, Ni, Mn and Cr are from combustion processes and vehicular traffic, whereas Pb, Zn and Cd came from traffic and geogenic contributions. Assessment using the pollution load index indicated that only dust from Zikoye–Bushika road, the junction of Zikoye–Bushika and Bududa–Manafwa roads and Manafwa town were substantially polluted as the indices were greater than 1. Further assessment of pollution degree of the dust samples using index of geo-accumulation revealed that the dusts were practically uncontaminated to medium-to-strongly contaminated. Health risk assessment showed that there are non-carcinogenic health risks that could emanate from direct ingestion of PTEs in dusts by children. This study therefore opens the lead for investigation of the contamination levels and the health risks of PTEs in dusts from industrial areas as well as busy Ugandan cities such as Kampala, Jinja, Mbarara and Gulu.Item Purple anthocyanin colouration on lower (abaxial) leaf surface of Hemigraphis colorata (Acanthaceae)(Phytochemistry, 2014) Skaar, Irene; Adaku, Christopher; Jordheim, Monica; Byamukama, Robert; Kiremire, Bernard; Andersen, Øyvind M.The functional significance of anthocyanin colouration of lower (abaxial) leaf surfaces is not clear. Two anthocyanins, 5-O-methylcyanidin 3-O-(300-(b-glucuronopyranosyl)-b-glucopyranoside) (1) and 5-O-methylcyanidin 3-O-b-glucopyranoside (2), were isolated from Hemigraphis colorata (Blume) (Acanthaceae) leaves with strong purple abaxial colouration (2.2 and 0.6 mg/g fr. wt., respectively). The glycosyl moiety of 1, the disaccharide 300-(b-glucuronopyranosyl)-b-glucopyranoside), has previously been reported to occur only in a triterpenoid saponin, lindernioside A. The structural assignment of the aglycone of 1 and 2 is the first complete characterisation of a natural 7-hydroxy-5-methoxyanthocyanidin. Compared to nearly all naturally occurring anthocyanidins, the 5-O-methylation of this anthocyanidin limits the type of possible quinoidal forms of 1 and 2 to be those forms with keto-function in only their 7- and 40-positionsItem Spatio-temporal Variations and Potential Health Risks of Heavy Metals in Water from River Manafwa, Uganda(Letters in Applied NanoBioScience, 2022) Opolot, Mark; Omara, Timothy; Adaku, Christopher; Ntambi, EmmanuelThe epicenter of flash flood inundations and landslides in Uganda have been areas around Mt. Elgon. By implication, it has led into loss of lives, food and water insecurity. This study assessed the seasonal variations in physiochemical parameters and heavy metals (HMs) content of water from River Manafwa (R. Manafwa) which is the major water source used around Mt. Elgon. Potential insidious human health risks associated with consumption and dermal contact with water from the river were assessed using target hazard quotient and incremental lifetime cancer risk methods. Results of atomic absorption spectrometry analysis showed that the concentrations of the HMs in the wet and dry seasons ranged from below detection limit to 1.407 ± 0.001 mg/L, which were below WHO limits. Health risk assessments indicated that there are discernable non-carcinogenic health risks from ingestion of water from R. Manafwa, as the total target hazard quotients were above 1 for some of the samples. Cancer risk values indicated that there are no potential cancer risks from ingestion of water from the river. This study recommends that regulatory authorities should intervene to mitigate pollution of R. Manafwa through strengthening restrictions on sand mining and dumping of wastes into the river.Item Variation of Cyanogenic Potential of Selected Cassava Varieties with Age in Zombo District, Uganda(International Refereed Journal of Arts, Science & Commerce, 2018) Oloya, Benson; Adaku, Christopher; Andama, MorganCassava is a major staple food in the developing world, providing a basic diet for around 500 million people. In Uganda, it is currently one of the most important food crops and ranks second to bananas in terms of area occupied, total production and per capita consumption. However, cassava contains cyanogenic glycosides such as linamarin and Lotaustralin, which are toxic. Consumption of such toxins in sufficient quantities can cause acute cyanide poisoning and death in humans and animals. Thus, cassava is a possible health risk to the consumers. Awareness about the trend of cyanogenic glycosides content in cassava as it matures is paramount in minimizing the health risks associated with cassava consumption. As such, the most common local cultivars; Bisimwenge, Nyar-anderiano, Nyar-udota, in Zombo district and two improved cultivars: NASE 9 and TME 14, were investigated for variation in their cyanogenic content with age. The concentrations of cyanogens were determined using standard titration method. The results showed that cyanogeniccontent was highest at the ages of 8-10 months and generally decreased after the tenth month. It is therefore safer to harvest cassava after at least ten months when the levels of the hydrogen cyanide have reduced and stabilized.