Bioactive scalemic caged xanthones from the leaves of Garcinia bracteata

• Published in: Bioorganic chemistry Vol. 82; pp. 274 - 283
• Main Authors: Zhang, Bao-Jun, Fu, Wen-Wei, Wu, Rong, Yang, Jin-Ling, Yao, Cai-Yun, Yan, Bing-Xiong, Tan, Hong-Sheng, Zheng, Chang-Wu, Song, Zhi-Jun, Xu, Hong-Xi
• Format: Journal Article
• Language: English
• Published: SAN DIEGO Elsevier Inc 01.02.2019; Elsevier
• Subjects: Biochemistry & Molecular Biology; Caged xanthones; Chemistry; Chemistry, Organic; Cytotoxicity; Garcibractatin A; Garcinia bracteate; Life Sciences & Biomedicine; Physical Sciences; Science & Technology; Garcinia bracteate; Garcibractatin A; Cytotoxicity; Caged xanthones; PRENYLXANTHONES; APOPTOSIS; NATURAL-PRODUCTS; GROWTH; DRUGS; STEM BARK; BIPHENYL DERIVATIVES
• ISSN: 0045-2068; 1090-2120
• DOI: 10.1016/j.bioorg.2018.10.041

[Display omitted] •Four pairs of new scalemic caged xanthones and twelve known ones were isolated.•The relative configuration of 1 was confirmed by X-ray crystallographic analysis.•Absolute configurations were determined by the comparison of measurements and calculations of ECD spectra and OR values.•HPLC-ECD analysis was a fast and reliable analytical approach for scalemic mixtures.•Compound 4 exhibited a low micromolar activity against four cancer cell lines. 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 IC50 values from 1.11 to 2.93 μM. A preliminary structure-activity relationship has been discussed, and some helpful conclusions have been drawn.