Antibacterial phenolic components from Eriocaulon buergerianum.

Five phenolic components, 1,3,6-trihydroxy-2,5,7-trimethoxyxanthone (1), 7,3'-dihydroxy-5,4',5'-trimethoxyisoflavone (2), toralactone-9-O-beta-D-glucopyranoside (3), patuletin-3-O-[2-O-E-feruloyl-beta-d-glucopyranosyl-(1-->6)-beta-d-glucopyranoside] (4), patuletin-3-O-[beta-d-glucopyranosyl-(1-->3)-2-O-E-caffeoyl-beta-D-glucopyranosyl-(1-->6)-beta-D-glucopyranoside] (5), along with 19 known compounds were isolated from Eriocaulon buergerianum (Eriocaulaceae). Their structures were determined by spectroscopic and chemical methods. All 24 isolated compounds were tested against the pathogenic bacteria Staphylococcus aureus (ATCC 25923); as a result, 10 compounds were found to exhibit antibacterial activity with MICs ranging from 32 to 256 microg/ml.