Highly Cytotoxic Xanthones from Cratoxylum cochinchinense Collected in Myanmar

Eight xanthones and one anthraquinone, together with four common triterpenoids, have been isolated from the barks of Cratoxylum cochinchinense, collected in Myanmar. The structures of the metabolites were elucidated by spectroscopic data analysis and their antiproliferative activities were measured against six human tumor cell lines, by using the MTT assay. Pruniflorone N (1) showed a significant cytotoxicity against all cancer cells with IC50 values in the range 3-9 μM, on average higher than the anticancer drug cisplatin. Instead, compounds 2 and 3 exhibited high antiproliferative activity against some specific cell lines.

Inhibition of nitric oxide production in lipopolysaccharide-activated RAW264.7 macrophages by isolated xanthones from the roots of Cratoxylum formosum ssp. pruniflorum

The inhibitory activity of extract and compounds isolated from the roots of Cratoxylum formosum ssp. pruniflorum against nitric oxide (NO) was evaluated using RAW264.7 cells. Isolation of the CH2Cl2 extract of C. formosum ssp. pruniflorum roots afforded ten known xanthones including six tri-oxygenated xanthones (1-6) and four tetra-oxygenated xanthones (7-10), respectively. Compound 7 showed the highest inhibitory activity against NO release with an IC50 value of 3.9 μM, followed by compound 8 with an IC50 value of 4.3 μM, respectively. In order to understand the mechanism of this anti-inflammatory activity, the transcriptional level of 7 was found to down regulate mRNA expressions of iNOS and COX-2 in dose-dependent manners, whereas 8 inhibited only iNOS mRNA expression but did not affect on that of COX-2 gene. Xanthones might be the main anti-inflammatory components in C. formosum ssp. pruniflorum.

Xanthones from the stems of Cratoxylum cochinchinense

Three xanthones, named cratoxylumxanthones B-D (1-3), along with five known xanthones (4-8), were isolated from the stems of Cratoxylum cochinchinense (Lour.) Blume. Their structures were elucidated by interpretation of spectroscopic data. Among these xanthones, cochinxanthone D (4) exhibited the most potent antioxidant activity in both the DPPH radical scavenging and the lipid peroxidation inhibition assays.