Bioactive scalemic caged xanthones from the leaves of Garcinia bracteata.

Authors :: Zhang BJ
Fu WW
Wu R
Yang JL
Yao CY
Yan BX
Tan HS
Zheng CW
Song ZJ
Xu HX
Source :: Bioorganic chemistry [Bioorg Chem] 2019 Feb; Vol. 82, pp. 274-283. Date of Electronic Publication: 2018 Oct 25.
Publication Year :: 2019
Abstract: Four pairs of previously undescribed caged xanthones (1-4) and twelve known caged xanthones (5-16) were isolated from the leaf extract of Garcinia bracteata. Their structures were unambiguously elucidated on the basis of spectroscopic methods. The planar structure and relative configuration of 1 was confirmed by X-ray crystallographic analysis. The enantiomers of compounds 1, 2, 4 were further resolved by semi-preparative chiral HPLC, and the absolute configurations of enantiomers of compounds 1 and 4 were determined by measurement and calculation of electronic circular dichroism (ECD) spectra and specific rotations. The inhibitory activities of the isolated compounds against human HeLa, A549, PC-3, HT-29, and WPMY-1 cell lines were assayed, and garcibractatin A (4) showed the most potent inhibitory activities in vitro with IC <subscript>50</subscript> values from 1.11 to 2.93 μM. A preliminary structure-activity relationship has been discussed, and some helpful conclusions have been drawn.<br /> (Copyright © 2018 Elsevier Inc. All rights reserved.)