Phenolic compounds from Baseonema acuminatum leaves: isolation and antimicrobial activity

Three new phenolic compds., 1-galloyl-beta-D-glucopyranosyl-(1-4)-beta-D-galactopyranoside (1), 2-methoxy-5-(1',2',3'-trihydroxypropyl)-phenyl-1-O-(6''-galloyl)-beta-D-glucopyranoside (2), and 2-methoxy-5-hydroxymethyl-phenyl-1-O-(6''-galloyl)-beta-D-glucopyranoside (3), together with the known compds. benzyl 6'-O-galloyl-beta-D-glucopyranoside (4), 1,6-di-O-galloyl-beta-D-glucopyranose (5), myrciaphenone B (6), kaempferol 3-O-(6''-galloyl)-beta-D-glucopyranoside (7), quercetin 3-O-(6''-galloyl)-beta-D-glucopyranoside (8), vomifoliol 9-O-beta-D-apiofuranosyl-(1-6)-beta-D-glucopyranoside, 2,3-dihydrobenzofuran-2-(4'-hydroxy-3'-methoxyphenyl)-3-alfa- L-rhamnopyranosyloxymethyl-7-methoxy-5-propanol, and benzyl-O-alfa-L-rhamnopyranosyl-(1-6)-beta-D-glucopyranoside were isolated from the leaves of Baseonema acuminatum P. Choux (Asclepiadaceae). Their structures were detd. by 1D- and 2D-NMR spectroscopy and by ESI-MS anal. The antimicrobial activity of all compds. was evaluated in vitro against bacteria (Staphylococcus aureus two strains, Bacillus cereus, Bacillus subtilis, Escherichia coli, Salmonella thyphimurium) and three strains of Candida albicans. The new compds. 2 and 3, together with the known compd. 4, showed antifungal activity against two clin. isolated Candida albicans strains and against C. albicans ATCC 2091; MIC values were in the range of 25- 100 microg/mL. Compd. 5 was active against the two clin. isolated strains of C. albicans with MICs of 12.5 microg/mL and 25 microg/mL. Compds. 1, 6, 7, and 8 inhibited only one strain of C. albicans at the max. concn. used. None of the phenolic compds. tested was active against the bacteria studied