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

Beta-mangostin is a xanthone commonly found in the genus Garcinia. Unlike α-mangostin, to date, there have only been a few studies on the biological activity and derivatization of ß-mangostin. In this study, two novel glycosylated derivatives of ß-mangostin were successfully synthesized via a one-pot enzymatic reaction. These derivatives were characterized as ß-mangostin 6-O-ß-d-glucopyranoside and ß-mangostin 6-O-ß-d-2-deoxyglucopyranoside by TOF ESI/MS and 1H and 13C 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 µM. The acetylcholinesterase and α-glucosidase inhibitory activities of ß-mangostin were determined with IC50 values of 2.17 and 27.61 µM, respectively. A strong anti-microbial activity of ß-mangostin against Gram-positive strains (Bacillus subtilis, Lactobacillus fermentum and Staphylococcus aureus) was observed, with IC50 values of 0.16, 0.18 and 1.24 µg 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 µg ml-1). The new derivatives of ß-mangostin showed weaker activities than those of ß-mangostin, demonstrating the important role of the hydroxyl group at C-6 of ß-mangostin in its bioactivity.