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Tectona grandis L. f. (Lamiaceae) is famous for timber production and has been used in traditional medicine for treating bronchitis, liver-related roubles, urinary discharge amongst other diseases. Methanol extract of the stem bark was investigated for in vivo antiophidian assay against Bitis arietans and Naja nigricollis. Also, the extract and chromatographic fractions were subjected to cytotoxicity tests using tadpole model and antiarthritic assay by proteinase inhibition. Chromatography of crude methanol extract afforded three highly polar vacuum liquid chromatography (VLC) fractions (BVLC-1, BVLC-2 and BVLC-3). BVLC-2 further gave four semi-pure uncharacterized isolates (I, II, III, IV). Only BVLC-2 and BVLC-3 were cytotoxic at 10 - 80 mg/ml, with BVLC-3 being most potent (100% mortality, LC50 40 mg/ml). Concentration-dependent proteinase enzyme inhibition (24 - 71%) at 200 - 1000 μg/ml of BVLC-2 was observed, and this was less (IC50 659.24 μg/ml) than the activity of the standard drug, acetyl salicylic acid. However, neutralization of B. arietans and N. nigricollis snake venoms using methanol extract was not dose-dependent, but the extract at
the least dose, 50 mg/kg offered better protection (75%) on Naja nigricollis envenomed-mice in 48 h. Its activity was comparable to that of the positive antivenin tested at 0.2 mg/kg. These findings justify the folkloric use of T. grandis in the treatment of snake bites, arthritic conditions, and oxidative stress-induced diseases.
Keywords: Tectona grandis, methanol extract, anti-snake venom activity, tadpole cytotoxicity, anti-arthritic activity