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

Abstract

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 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 β-mangostin were determined with IC₅₀ 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 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 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.

Keywords: acetylcholinesterase; glycosylation; β-mangostin.