Browsing by Author "Yenesew, Abiy"

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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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    A Coumestan and a Coumaronochromone from Millettia Lasiantha
    (Biochemical Systematics and Ecology, 2021) Buyinza, Daniel; Derese, Solomon; Ndakala, Albert; Yenesew, Abiy; Koch, Andreas; Oriko, Richard
    The manuscript describes the phytochemical investigation of the roots, leaves and stem bark of Millettia lasiantha resulting in the isolation of twelve compounds including two new isomeric isoflavones lascoumestan and lascoumaronochromone. The structures of the new compounds were determined using different spectroscopic techniques.
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    Cytotoxicity of Isoflavones from Millettia Dura
    (Natural Product Research, 2021) Buyinza, Daniel; Yang, Li Jun; Derese, Solomon; Ndakala, Albert; Wong, Vincent Kam Wai; Möller, Heiko M.; Yenesew, Abiy
    The first phytochemical investigation of the flowers of Millettia dura resulted in the isolation of seven isoflavones, a flavonol and a chalcone. Eleven isoflavones and a flavonol isolated from various plant parts from this plant were tested for cytotoxicity against a panel of cell lines, and six of these showed good activity with IC50 values of 6-14 μM. Durmillone was the most active with IC50 values of 6.6 μM against A549 adenocarcinomic human alveolar basal epithelial cancer cell line with low cytotoxicity against the non-cancerous cell lines BEAS-2B (IC50 = 58.4 μM), LO2 hepatocytes (IC50 78.7 μM) and CCD19Lu fibroblasts (IC50 >100 μM).
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    Naphthoquinones from the Roots of Aloe Secundiflora
    (Phytochemistry Letters, 2012) Indul, Martha; Cheloti, Michael; Wasuna, Antonina; Wekesa, Ingrid; Wanjohi, John M.; Byamukama, Robert; Heydenrich, Matthias; Makayoto, Moses; Yenesew, Abiy
    Two new naphthoquinones, 5-hydroxy-3,6-dimethoxy-2-methylnaphthalene-1,4-dione and 5,8-dihydroxy- 3-methoxy-2-methylnaphthalene-1,4-dione, were isolated from the roots of Aloe secundiflora together with the known compounds chrysophanol, helminthosporin, isoxanthorin, ancistroquinone C, aloesaponarins I and II, aloesaponols I and II, laccaic acid D methyl ester and asphodelin. The structures were elucidated based on spectroscopic evidence. This appears to be the first report on the occurrence of naphthoquinones in the genus Aloe. Aloesaponarin I and 5-hydroxy-3,6-dimethoxy-2-methylnaphthalene- 1,4-dione showed anti-bacterial activity against Mycobacterium tuberculosis with MIC values of 21– 23 mg/mL in the Microplate Alamar Blue Assay (MABA) and Low Oxygen Recovery Assay (LORA); 5- hydroxy-3,6-dimethoxy-2-methylnaphthalene-1,4-dione also showed cytotoxicity against the Vero cell line (IC50 = 10.2 mg/mL).