Browsing by Author "Philips, T.J."
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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 In vitro antileishmanial activity and molecular docking studies of lupeol and monostearin, isolated from Parkia biglobosa(Scientific African, 2023) Osafo, T.; Philips, T.J.; Adomako, A.K.; Borquaye, L.S.; Ekuadzi, E.; Appiah-Opong, R.; Dickson, R.A.Parkia biglobosa (Leguminosae) is used traditionally for managing leishmaniasis. However, there are no reports of the antileishmanial constituents from the plant. This study is aimed at isolating antileishmanial compounds, from the stem bark of P. biglobosa, and assessing their mechanism of action using molecular docking studies. Bioassay-guided fractionation led to the isolation of two known compounds, lupeol and monostearin. Their structures were elucidated using their mass spectra. Using the 3-(4,5-dimethylthiazol-2- yl)-5-(3-carboxymathoxyphenyl)-2-(4-sulfophenyl)-2H-tretrazolium (MTS) assay, the evaluated antileishmanial effects of lupeol (1) and monostearin (2) showed IC50 values of 164.42 and 151.99 μg/mL respectively. The antileishmanial effects of the crude extract, non-polar, mid-polar and polar fractions were determined to be 64.43, 126.25, 725.65 and 167.52 μg/mL respectively. Molecular docking studies of the two isolates within the active sites of two validated targets in the Leishmania parasite: trypanothione reductase (TR) and pteridine reductase 1 (PTR1), showed that both compounds established important interactions with key amino acid residues in both proteins. Lupeol exhibited binding affinities of -7.1 kcal/mol and -10.2 kcal/mol for TR and PTR1, respectively, better than monostearin in both cases. Our findings back the claim that P. biglobosa stem bark possesses antileishmanial effects. Furthermore, the isolates lupeol and monostearin may be partly responsible for the observed activities.