Browsing by Author "Wabo, H.K."
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Item Antileishmanial and cytotoxic activities of a new limonoid and a new phenyl alkene from the stem bark of Trichilia gilgiana (Meliaceae)(Natural Product Research, 2019-01) Kowa, T.K.; Cieckiewicz, E.; Philips, T.J.; Dotse, E.; Tchokouaha, L.R.Y.; Wabo, H.K.; Tchinda, A.T.; Tane, P.; Frédérich, M.One new limonoid, trigilgianin (1), one new phenyl alkene, epoxy gilgialkene (2), together with five known compounds: scopoletin (3), sitosteryl-6'-O-undecanoate-β-D-glucoside (4), sitosteryl-O-β-D-glucopyranoside (5), cinchonain A (6) and cinchonain B (7) were isolated from the stem bark of Trichilia gilgiana Harms. (Meliaceae). All compounds were isolated for the first time from this species. The structures were elucidated on the basis of spectral studies and by comparison of these data with those from the literature. Compounds 1, 2, 3, 6 and 7 were tested for in vitro antileishmanial activity against visceral leishmaniasis parasite Leishmania donovani and cytotoxicity against macrophage RAW 264.7 cell line. Compounds 1 and 3 showed the highest antileishmanial activity (IC50 values of 6.044 and 6.804 µg/mL, respectively) with low cytotoxicity (CC50 values of >200 and 47.47 µg/mL, respectively), while compound 2 was moderately active on L. donovani promastigotes (IC50 56.81 µg/mL).Item Antipromastigote and cytotoxic activities of some chemical constituents of Hypericum lanceolatum Lam. (Guttifereae)(Journal of Applied Pharmaceutical Science, 2020-01) Tchokouaha, L.R.Y.; Kowa, T.K.; Nyemb, J.N.; Wabo, H.K.; Tchinda, A.T.; Appiah-Opong, R.; Agbor, G.A.; Tane, P.; Frederich, M.Phytochemical investigation of the ethanol extract of the stem bark of Hypericum lanceolatum Lam. (Guttifereae) afforded eight known compounds including 2,2ʹ,5,6ʹ-tetrahydroxybenzophenone (1), 5-hydroxy-3-methoxyxanthone (2), 3-hydroxy-5-methoxyxanthone (3), betulinic acid (4), hydroquinone (5) 6,7-dihydroxy-1,3-dimethoxyxanthone (6), calophyllumin A (7), and 1,3,5,6-tetrahydroxy-4-prenylxanthone (8). Compound 1 was submitted to acetylation reaction to give 5-acetoxy-2,2ʹ,6ʹ-trihydroxybenzophenone (9), a new hemisynthetic derivative. Compounds 5 and 8 were isolated for the first time from this plant. The structures were established by extensive analysis of their mass spectrometry and nuclear magnetic resonance (NMR) spectroscopic data and comparison with those from the literature. The isolated compounds (1, 2, 4, 5, and 8) and the derivative of benzophenone (9) were tested for their antipromastigote and cytotoxic activities against visceral leishmaniasis parasite Leishmania donovani and macrophage RAW 264.7 cell line, respectively. Compound 9 was the most active with an IC50 value of 6.1 μg/ml, while compounds 1, 2, 4, and 8 were moderately active with IC50 values ranging from 11.4 to 34.8 μg/ml against L. donovani and were not cytotoxic except compound 5 that was very toxic and not active. The findings of the present study suggested that compounds 1, 2, 4, and 8 could be considered as a potential source of therapeutic medicine for the treatment of leishmaniasis