rubraxanthone and mangostin

Two new xanthones: mangostanaxanthones I (3) and II (5) were isolated from the pericarp of Garcinia mangostana, along with four known xanthones: 9-hydroxycalabaxanthone (1), parvifolixanthone C (2), α-mangostin (4), and rubraxanthone (6). Their structures were elucidated on the basis of IR, UV, 1D, 2D NMR, and MS spectroscopic data, in addition to comparison with literature data. The isolated compounds were evaluated for their antioxidant, antimicrobial, and quorum-sensing inhibitory activities. Compounds 3 and 5 displayed promising antioxidant activity with IC50 12.07 and 14.12 μM, respectively using DPPH assay. Compounds 4-6 had weak to moderate activity against Escherichia coli and Staphylococcus aureus, while demonstrated promising action against Bacillus cereus with MICs 0.25, 1.0, and 1.0mg/mL, respectively. The tested compounds were inactive against Candida albicans. However, they showed selective antifungal potential toward Aspergillus fumigatus. Compounds 3 and 4 possessed quorum-sensing inhibitory activity against Chromobacterium violaceum ATCC 12472.

Topics: Anti-Bacterial Agents; Antifungal Agents; Antioxidants; Fruit; Garcinia mangostana; Microbial Sensitivity Tests; Molecular Structure; Quorum Sensing; Xanthones

Two new geranylated xanthones, 6-O-methylcowanin (4) and oliverixanthone (5), along with five known compounds, cowanin, rubraxanthone, cowaxanthone, cowanol, and beta-mangostin, have been isolated from the bark of Garcinia oliveri. For comparison of their biological activities, one mono- and seven di-O-alkylated alpha-mangostin derivatives were synthesized from alpha-mangostin. The structures of all compounds were assigned by spectroscopic methods (1D and 2D NMR and MS). Cytotoxicity of selected xanthones against MCF-7 and DLD-1 cell lines was examined. Evaluation of the structure-activity relationship showed that alpha-mangostin had the strongest activity, and all the O-alkylated alpha-mangostin derivatives showed reduced activity compared to the naturally occurring alpha-mangostin.

Topics: Cell Line; Cell Proliferation; Garcinia; Humans; Molecular Structure; Plant Bark; Stereoisomerism; Structure-Activity Relationship; Xanthones