Prenylated xanthones and benzophenones from the fruits of Garcinia bracteata and their potential antiproliferative and anti-inflammatory activities

Abstract

Ten previously undescribed compounds, including five prenylated xanthones (1–5), two caged xanthones (16–17) and three rearranged benzophenones (27–29), together with nineteen known compounds were isolated from the fruits of Garcinia bracteata. Their structures were established on the basis of spectroscopic analysis, electronic circular dichroism calculations, and X-ray crystallographic data. Compound 17 was a caged xanthone bearing a rare 8, 8a-epoxy moiety. Compound 28 belonged to the rearranged benzophenones with rare 2, 7-dioxabicyclo-[2.2.1] heptane moiety fused at C-2 and C-3 respectively. The antiproliferative and anti-inflammatory activities of all isolated compounds were evaluated. Compounds 23 and 24 exhibited remarkable inhibitory activities against three human cancer cell lines (HepG2, T98, MCF-7) with IC50 values ranging from 3.21 ± 1.00 to 6.27 ± 1.03 μM. Moreover, compounds 20 and 24 also displayed significant inhibitory effects against NO production with IC50 values of 1.22 ± 0.01 and 1.77 ± 0.23 μM respectively. These results enrich the structural diversities of xanthones and benzophenones from Garcinia plants. Neobractatin (24) due to its anti-tumor and anti-inflammatory effects is worth further investigation in anticancer research.