Cytotoxic activity of Guettarda pohliana Müll. Arg. (Rubiaceae).

The cytotoxic activity of crude extracts and their fractions from leaves and roots of G. pohliana was assessed against nine human cancer cell lines: melanoma (UACC-62), breast (MCF-7), breast expressing the multidrug resistance phenotype (NCI-ADR), lung (NCI-460), prostate (PCO-3), kidney (786-0), ovarian (OVCAR), colon (HT-29) and leukaemia (K-562). The hexane fraction from leaves (HL) and ethyl acetate (EAR), chloroform (CR) and hydromethanolic (HMR) fractions from roots were the most active fractions against K-562 with GI₅₀ values being lower than 1 μg mL⁻¹. Also, CR and HMR fractions were active against UACC-62 cell line in the same order of magnitude. The phytochemical study of the CR fraction allowed identifying the known iridoids secoxyloganin, sweroside and loganin.