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Bioassay-Guided Isolation of Prenylated Xanthone Derivatives from the Leaves of Garcinia oligantha

Tang, Yue-Xun, Fu, Wen-Wei, Wu, Rong, Tan, Hong-Sheng, Shen, Zhen-Wu, Xu, Hong-Xi
Journal of natural products 2016 v.79 no.7 pp. 1752-1761
Garcinia, X-ray diffraction, anticarcinogenic activity, cell growth, circular dichroism spectroscopy, fractionation, humans, inhibitory concentration 50, leaves, neoplasm cells, nuclear magnetic resonance spectroscopy, spectral analysis, xanthone
Four new dihydroxanthone derivatives (1–4), four new tetrahydroxanthone derivatives (5–8), two new xanthone derivatives (9 and 10), and two known caged tetrahydroxanthones were isolated from extracts of the leaves of Garcinia oligantha by bioassay-guided fractionation. These structures of the new compounds were elucidated by NMR and MS spectroscopic data analysis, and the absolute configurations of compounds 1 and 5–7 were determined by electronic circular dichroism and/or single-crystal X-ray diffraction analysis. Compounds 6–9 were shown to be unusual xanthone derivatives with an isopropyl group, which was confirmed by the X-ray crystallographic structure of compound 8. The inhibitory activities of these isolates against four human tumor cell lines (A549, HepG2, HT-29, and PC-3) were assayed, and compounds 1, 2, 5, 11, and 12 showed inhibitory effects on tumor cell growth, with IC₅₀ values ranging from 2.1 to 8.6 μM.