A New Tropane Alkaloid And Other Metabolites From Erythroxylum Macrocalyx (Erythroxylaceae) And Their Antiproliferative Activities

A new tropane alkaloid 7 beta-acetoxy-6 beta-benzoyloxy-3 alpha-hydroxytropane (1) was isolated from the twigs of Erythroxylum macrocalyx Mart. (Erythroxylaceae), along with the known substances: 6 beta,7 beta-dibenzoyloxy-3 alpha-hydroxytropane (2), 6 beta,7 beta-dihydroxy-3 alpha-(phenylacetoxy)tropane (3), 3 alpha-benzoyloxy-6 beta,7 beta-dihydroxytropane (4), 6 beta-benzoyloxy-3 alpha-(4-hydroxy-3, 5-dimetoxybenzoyloxy)tropane (5), ombuin-3-rutinoside-5-glucoside (6), lupeol (7), taraxerol (8) and lupenone (9). Compounds 1 and 2 were also isolated from the leaves. The structures were established by analyses of 1D- and 2D-NMR and MS data, as well as by comparison with literature data for known compounds. The structure of 2 was also supported by X-ray crystallography analyses. The compounds were evaluated in vitro for their antibacterial and antiproliferative activities. Compound 5 showed high antiproliferative activity on liver hepatocellular carcinoma cells (HepG2) with IC50 value of 3.66 mu g mL(-1) (8.29 mu mol L-1), but no cytotoxic effect (IC50 > 25 mu g mL(-1)) on human lymphoblast cell line. This study reveals the potential use of 5 as prototype for the synthesis of new antiproliferative agents.