Bioactivities of β-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 β-mangostin. In this study, two novel glycosylated derivatives of β-mangostin were successfully synthesized via a one-pot enzymatic reaction. These derivatives were characterized as β-mangostin 6-O-β-d-glucopyranoside and β-mangostin 6-O-β-d-2-deoxyglucopyranoside by TOF ESI/MS and 1 H and 13 C NMR analyses. Beta-mangostin showed cytotoxicity against KB, MCF7, A549 and HepG2 cancer cell lines, with IC 50 values ranging from 15.42 to 21.13 µM. The acetylcholinesterase and α-glucosidase inhibitory activities of β-mangostin were determined with IC 50 values of 2.17 and 27.61 µM, respectively. A strong anti-microbial activity of β-mangostin against Gram-positive strains ( Bacillus subtilis , Lactobacillus fermentum and Staphylococcus aureus ) was observed, with IC 50 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 IC 50 and MIC values greater than the tested concentration (greater than 32 µg ml -1 ). The new derivatives of β-mangostin showed weaker activities than those of β-mangostin, demonstrating the important role of the hydroxyl group at C-6 of β-mangostin in its bioactivity.