[Show abstract][Hide abstract] ABSTRACT: Garcinia xanthochymus has been widely used in traditional Chinese medicine for expelling worms and removing food toxins. Bioassay-guided fractionation of an EtOAc-soluble extract of G. xanthochymus stem bark led to the isolation of six new xanthones. Their structures were elucidated by spectroscopic methods, especially 2D-NMR techniques. Free-radical-scavenging activities of the isolated compounds were elucidated through DPPH method. Most of the isolated compounds showed considerable free radical scavenging activity on DPPH assay. Compound 1 exhibited effective antioxidant scavenging activity against DPPH radical with an IC₅₀ value of 19.64 μM, and compound 6 showed the lowest activity among all the tested molecules, with an IC₅₀ value of 66.88 μM. These findings support the notion that the plant genus Garcinia is a good source of bioactive compounds.
[Show abstract][Hide abstract] ABSTRACT: To study xanthones from the barks of Garcinia xanthochymus, the constituents were isolated by normal-phase and reverse-phase silica gel column chromatography from the EtOAc extract. Their structures were elucidated by spectral analysis. Three new xanthones were purified and identified as 1,2,5-trihydroxy-6-methoxyxanthone (1), 1,4,6-trihydroxy-5-methoxyxanthone (2), 1,2,7-trihydroxy-4-(1,1-dimethylallyl) xanthone (3).
Preview · Article · Oct 2008 · Yao xue xue bao = Acta pharmaceutica Sinica
[Show abstract][Hide abstract] ABSTRACT: A new bis-xanthone (xanthone=9H-xanthen-9-one), named bigarcinenone A (1) which is the first example of a bis-xanthone with the xanthone–xanthone linkage between an aromatic C-atom and a C5 side chain from a guttiferae plant, a new phloroglucinol (=benzene-1,3,5-triol) derivative, named garcinenone F (2), together with seven known xanthones were isolated from the bark of Garcinia xanthochymus. Their structures were elucidated by spectroscopic methods, especially 2D-NMR techniques. Bigarcinenone A (1) exhibited potent antioxidant activity in the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging test with a IC50 value of 9.2 μM, compared to the positive control, the well-known antioxidant butylated hydroxytoluene (BHT) with a IC50 of 20 μM (Table 3).