ABSTRACT

Antiaris africana plant commonly known as "false iroko" tree is one of the medicinal plants used in the treatment of mental and nervous disorder such as epilepsy, treatment of respiratory infections, syphilis and skin irritants in Nigeria. Analysis of the phytochemical properties of the leaves indicated the presence of tannins (45.86 ± 2.04 %), flavonoids (1.67 + 0.11%), saponins (4.56 ± 0.0 1%) and cardiac glycoside (1.80 ± 0.02%). GC-MS analysis of the ethanol extract of the leaves showed twenty five (25) peaks representing compounds with their various percentage compositions, molecular formulae, molecular weight and the retention times, two of which were of interest. The two compounds were characterized using IR, 'H NMR, '3C NMR, MS, COSY and DEPT. The spectral analysis showed that the two compounds are esters and were named as (1E, 3E)-4-(6, 7, 8, 9, 10, 13, 14, 15, 16, 17-decahydro-17-hydroxy-5, 10, 13, 14-tetra methyl-5H-cyclopenta [a] phenanthrene- 16-yl) buta- 1,3 -dienyl-2-phenyl acetate (ester) and hexadecahydro — 3, 17 — dihydroxy — 5, 10, 13, 14 — tetramethyl — 1 H- cyclopenta [ a] phenanthren — 17 — yl, 7 — methyl octanoate. These esters may be responsible for the biological activities exhibited by Antiaris africana. The crude extract of the leaves of A. africana and the isolated compounds showed potent free radical scavenging activities in two models — the DPPH (a,a-diphenyl-3-picrylhydrazyi) and the Ferric Thiocyanate models. The crude extract showed more antioxidant activity in the two models than the pure compounds which might be attributed to the presence of phytochemicals in the extract. These phytochemicals were believed to have exhibited synergistic antioxidative action, suggesting the potential application of the leaves of the plant as antioxidative agents