Cytotoxic activities of fractionated ethanol extract of the root bark of terminalia catappa and isolation of eriodictyol-7-O-β-D-glucopyranoside from the ethyl acetate soluble fraction

Abstract

The crushed root bark of terminalia catappa Linn was extracted using aqueous ethanol. The crude extract was suspended in water and successively partition into n-hexane, dichloromethane, ethyl acetate and n-butanol soluble fractions. The fractions i.e.; n-hexane, dichloromethane, ethyl acetate, n-butanol and water were subjected to cytotoxic activity using brine shrimp lethality bioassay and proton nuclear magnetic resonance (¹H NMR) analyses. The cytotoxicity of the isolates were evaluated in terms of lethality concentration (LC₅₀). Comparing the result obtained to vincristine sulphate with LC₅₀ of 0.61 μg/ml, ethyl acetate and n-hexane fractions demonstrated a significant cytotoxic activity having LC₅₀ value of 0.82 μg/ml and 1.21 μg/ml. The LC50 values of the water, dichloromethane and n-butanol fractions were 11.90 μg/ml, 13.25 μg/ml and 17.10 μg/ml respectively. The ethyl acetate fraction with significant activity in in-vitro cytotoxic activity and a good proton NMR profiles, was further fractionated and purified using column chromatography, preparative thin layer chromatography (PTLC) and the isolate obtained were characterized using spectroscopic techniques (MS, IR, ¹H and ¹³C NMR, ¹H-¹H COSY and ¹H-¹³C HSQC). We concluded that the compound isolated was eriodictyol-7- O-β-D-glucopyranoside.