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Nigerian Journal of Natural Products and Medicine

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Antioxidant activity and cytotoxicity study of Leucaena leucocephala (Lam.) de wit leaf extract constituents

M.A Aderogba, L.J McGaw, B.T Bezabih, B.M Abegaz

Abstract


Antioxidant activity of the solvent fractions obtained from a 20% aqueous methanol dried leaf extract of Leucaena leucocephala was evaluated using a 1, 1-diphenyl-2-picrylhydrazyl (DPPH) TLC assay. The more polar fractions ethyl acetate and butanol fractions demonstrated strong activity. A DPPH activity-guided fractionation procedure was used to isolate the antioxidant constituents of these active fractions. Separate fractionation of the fractions led to the isolation of epicatechin-3-O-gallate (1) along with two quercetin glycosides: quercetin-3-O-arabinofuranoside (2) and quercetin-3-O-rhamnoside (3) together with apigenin (4). The structures of the isolated compounds were elucidated using spectroscopic techniques NMR (1D and 2D) and mass spectrometry. Compounds 1 and 4 are reported for the first time from this species. In the qualitative antioxidant TLC assay, isolated compounds instantly bleached the DPPH (0.2% in MeOH) purple colour indicating strong antioxidant activity. The antioxidant quercetin glycosides were not cytotoxic at the highest concentration tested (200 ìg/ml), and apigenin was not isolated in sufficient quantity to test for cytotoxicity. Epicatechin-3-O-gallate showed slight cytotoxicity against Vero cells (LC50 = 92 μg/ml).

Keywords: Leucaena leucocephala, Fabaceae, antioxidant, DPPH, cytotoxicity.

 




http://dx.doi.org/10.4314/njnpm.v13i1.61612
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