Bioactivities of beta-mangostin and its new glycoside derivatives synthesized by enzymatic reactions

Beta-mangostin is a xanthone commonly found in the genus Garcinia. Unlike a-mangostin, to date, there have only been a few studies on the biological activity and derivatization of beta-mangostin. In this study, two novel glycosylated derivatives of beta-mangostin were successfully synthesized via a one-pot enzymatic reaction. These derivatives were characterized as beta-mangostin 6-O-beta-D-glucopyranoside and beta-mangostin 6-O-beta-D-2-deoxyglucopyranoside by TOF ESI/MS and H-1 and C-13 NMR analyses. Beta-mangostin showed cytotoxicity against KB, MCF7, A549 and HepG2 cancer cell lines, with IC50 values ranging from 15.42 to 21.13 mu M. The acetylcholinesterase and a-glucosidase inhibitory activities of beta-mangostin were determined with IC50 values of 2.17 and 27.61 mu M, respectively. A strong anti-microbial activity of beta-mangostin against Grampositive strains (Bacillus subtilis, Lactobacillus fermentum and Staphylococcus aureus) was observed, with IC50 values of 0.16, 0.18 and 1.24 mu g ml(-1), respectively. Beta-mangostin showed weaker activity against Gram-negative strains (Salmonella enterica, Escherichia coli and Pseudomonas aeruginosa) as well as Candida albicans fungus, with IC50 and MIC values greater than the tested concentration (greater than 32 mu g ml(-1)). The new derivatives of beta-mangostin showed weaker activities than those of beta-mangostin, demonstrating the important role of the hydroxyl group at C-6 of beta-mangostin in its bioactivity.