Dihydroosajaxanthone: A New Natural Xanthone from the Branches of Garcinia Schomburgkiana Pierre.

Garcinia schomburgkiana, locally known in Thailand as an edible fruit "Ma-dan", is a plant species of the Clusiaceae family which has been reported as sources of a variety of compounds with biological activities. In the phytochemical studies of Ma-dan, four xanthones were, for the very first time, isolated from the branch acetone extract of G. schomburgkiana. Their structures were determined through the analysis of spectroscopic data (1H, 13C-NMR, IR and MS) and the comparison with those previously reported. Dihydroosajaxanthone (1), an original synthetic xanthone, is reported herein for the first time as a naturally occurring xanthone, together with three known xanthones: xanthochymone A (2), 1,3,7-trihydroxy-2-(3-hydroxy-3-methylbutyl) xanthone (3) and 1,3,5,6-tetrahydroxyxanthone (4). These compounds, especially dihydroosajaxanthone (1), might be considered as chemotaxonomic markers of the Garcinia genus.

Antityrosinase and antimicrobial activities from Thai medicinal plants.

Various dermatological disorders and microbial skin infection can cause hyperpigmentation. Therefore, screenings for whitening and antimicrobial agents from Thai medicinal plants have been of research interest. Seventy-seven ethanol plant extracts were investigated for antityrosinase activity, eleven samples showed the tyrosinase inhibition more than 50 % were further preliminary screening for antimicrobial activity by agar disc diffusion and broth micro-dilution methods. Artocarpus integer (Thunb.) Merr. (Moraceae) root extract, which showed the potential of tyrosinase inhibition with 90.57 ± 2.93 % and antimicrobial activity against Staphylococcus aureus, S. epidermidis, Propionibacterium acnes and Trichophyton mentagophytes with inhibition zone as 9.10 ± 0.00, 10.67 ± 0.09, 15.25 ± 0.05 and 6.60 ± 0.17 mm, respectively was selected for phytochemical investigation. Three pure compounds were isolated as artocarpin, cudraflavone C and artocarpanone. And artocarpanone exhibited anti-tyrosinase effect; artocarpin and cudraflavone C also showed the potential of antibacterial activity against S. aureus, S. epidermidis and P. acnes with MIC at 2, 4 and 2 µg/ml, respectively and MBC at 32 µg/ml for these bacteria. So, these pure compounds are interesting for further study in order to provide possibilities of new whitening and antibacterial development. This will be the first report of phytochemical investigation of A. integer root.