Browsing by Author "Heydenreich, Matthias"

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    Antimycobacterial Activity of the Extract and Isolated Compounds From the Stem Bark of Zanthoxylum leprieurii Guill. and Perr.
    (Natural Product Communications, 2021) Oloya, Benson; Namukobe, Jane; Heydenreich, Matthias; Ssengooba, Willy; Schmidt, Bernd; Byamukama, Robert
    Zanthoxylum leprieurii Guill. and Perr. (Rutaceae) stem bark is used locally in Uganda for treating tuberculosis (TB) and cough-related infections. Lupeol (1), sesamin (2), trans-fagaramide (3), arnottianamide (4), (S)-marmesinin (5), and hesperidin (6) were isolated from the chloroform/methanol (1:1) extract of Z. leprieurii stem bark. Their structures were elucidated using spectroscopic techniques and by comparison with literature data. Furthermore, the extract and isolated compounds were subjected to antimycobacterial activity. The extract exhibited moderate activity against the susceptible (H37Rv) TB strain, but weak activity against the multidrug resistant (MDR)-TB strain with minimum inhibitory concentrations (MICs) of 586.0 and 1172.0 μg/mL, respectively. Compound 3 (trans-fagaramide) showed significant antimycobacterial activity against the susceptible (H37Rv) TB strain (MIC 6 μg/mL), but moderate activity against the MDR-TB strain (MIC 12.2 μg/mL). Compounds 2, 5, 6, and 1 showed moderate activitiesagainst the susceptible (H37Rv) strain (MIC 12.2-98.0 μg/mL) and moderate to weak activities against theMDR-TB strain (MIC24.4-195.0 μg/mL). This study reports for the first time the isolation of compounds 1 to 6 from the stem bark of Z leprieurii. trans-Fagaramide (3) may present a vital template in pursuit of novel and highly effective TB drugs
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    Antiplasmodial Quinones from the Rhizomes of Kniphofia foliosa
    (Natural product communications, 2013) Induli, Martha; Gebru, Meron; Abdissa, Negera Abdissa; Akala, Hosea; Wekesa, Ingrid; Byamukama, Robert; Heydenreich, Matthias; Murunga, Sylvia; Dagne, Ermias; Yenesew, Abiy
    Extracts of the rhizomes of Kniphofia foliosa exhibited antiplasmodial activities against the chloroquine-sensitive (D6) and chloroquine-resistant (W2) strains of Plasmodium falciparum with IC50 values of 3–5 g/mL. A phenyloxanthrone, named 10-acetonylknipholone cyclooxanthrone (1) and an anthraquinoneanthrone dimer, chryslandicin 10-methyl ether (2), were isolated from the rhizomes, along with known quinones, including the rare phenylanthraquinone dimers, joziknipholones A and B. The structures of these compounds were determined based on spectroscopic data. This is the second report on the occurrence of the dimeric phenylanthraquinones in nature. In an in vitro antiplasmodial assay of the isolated compounds, activity was observed for phenylanthraquinones, anthraquinone-anthrone dimers and dimeric phenylanthraquinones, with joziknipholone A being the most active. The new compound, 10-acetonylknipholonecyclooxanthrone, also showed anti-plasmodial activity. In an in vivo assay, knipholone anthrone displayed marginal antimalarial activity
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    Bioactive compounds in the stem bark of Albizia coriaria (Welw. ex Oliver)
    (International Journal of Biological and Chemical Sciences, 2015) Byamukama, Robert; Barbara, Ganza; Namukobe, Jane; Heydenreich, Matthias; Kiremire, Bernard T.
    Albizia coriaria was investigated for the bioactive compounds present in its stem bark. The plant was selected on the basis of its widespread use in traditional herbal medicine. Extraction of the plant material was done with ethyl acetate, methanol and water and the bioactivity of each extract was tested against Pseudomonas aeruginosa and Escherichia coli. Separation and purification of the compounds in the most active (ethyl acetate) extract was done using a combination of chromatographic techniques. The compounds were identified by 1D and 2D -1H and 13C NMR techniques as well as Mass spectrometry (MS). Six compounds, namely: Lupeol (1), Lupenone (2), Betulinic acid (3), Acacic acid lactone (4), (+) – Catechin (5) and Benzyl alcohol (6) were identified and characterized from the ethyl acetate extract. The results of the bioactivity tests carried out in this study indicated that A. coriaria has potential antimicrobial activity. Four of the characterized compounds (1, 2, 3 & 5) have a wide range of biological activity reported in literature. This justifies the use of this plant in traditional medicine and indicates a promising potential for the development of medicinal agents from A. coriaria stem bark.
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    Bioactive secondary metabolites from the leaves of Secamone africana (Olive.) Bullock
    (International Journal of Biological and Chemical Sciences, 2020) Sekandi, Peter; Namukobe, Jane; Byamukama, Robert; Akala, Hoseah M.; Yeda, Redemptah A.; Heydenreich, Matthias
    Secamone africana leaves are used in the treatment of malaria and other ailments in Uganda. The aim of the study was to characterize the antiplasmodial compounds from the leaves of Secamone africana. The leaves were extracted sequentially using dichloromethane (DCM) and methanol (MeOH). The crude extracts and isolated compounds were evaluated for their antiplasmodial activity against the chloroquine sensitive Sierraleone I (D6) and chloroquine-resistant Indochina I (W2) strains of Plasmodium falciparum. Isolation and purification were done using chromatographic techniques including column chromatography and high performance liquid chromatography. The isolated compounds were characterized using spectroscopic methods. The MeOH extract (IC50 = 5.45 μg/mL) was found to be more active than the DCM extract (IC50= 15.93 μg/mL) against the D6 malaria parasite. Chemical investigation of the MeOH extract yielded one new compound; 2-(2,4-dimethyloxetan-2-yl) acetic acid (3) in addition to the six known compounds; α-linolenic acid (1), conduritol B (4), β-sitosterol (5), 3,4-dihydroxybenzoic acid (6), 4-hydroxybenzoic acid (7) and coumaric acid (8). The DCM extract yielded one known compound: 1-methyl cyclobutene (2). The presence of these compounds with good anti-plasmodial activities and other bioactivities reported in literature, appears to argue for the therapeutic potential of Secamone africana.