Resolution and identification of scalemic caged xanthones from the leaf extract of Garcinia propinqua having potent cytotoxicities against colon cancer cells

Authors

Teerayut Sriyatep, Mae Fah Luang University
Cholpisut Tantapakul, Mae Fah Luang University
Raymond J. Andersen, University of British Columbia
Brian O. Patrick, University of British Columbia
Stephen G. Pyne, University of WollongongFollow
Chatchai Muanprasat, Mahidol University
Sawinee Seemakhan, Mahidol University
Suparerk Borwornpinyo, Mahidol University
Surat Laphookhieo, Mae Fah Luang UniversityFollow

RIS ID

117041

Publication Details

Sriyatep, T., Tantapakul, C., Andersen, R. J., Patrick, B. O., Pyne, S. G., Muanprasat, C., Seemakhan, S., Borwornpinyo, S. & Laphookhieo, S. (2018). Resolution and identification of scalemic caged xanthones from the leaf extract of Garcinia propinqua having potent cytotoxicities against colon cancer cells. Fitoterapia, 124 34-41.

Abstract

A new scalemic 8,8a-dihydro caged xanthone (1) was isolated from the leaf extract of Garcinia propinqua. Five other known natural products, the three caged xanthones (2, 5 and 6) and the two neocaged xanthones, (3 and 4) were also isolated as scalemic mixtures. Their structures were characterized by spectroscopic methods. The enantiomeric ratios (er) of compounds 1-6 ranged from 1:0.7 to 1:0.9. These compounds were also resolved by semipreparative chiral HPLC. The absolute configurations of (+)-2 and (+)-3 were determined by single-crystal X-ray diffraction analysis using Cu Kα radiation while the absolute configurations of the other compounds were determined by comparisons of their ECD spectra. Compounds (-)-4, (+)-4, (-)-5, (+)-5, and (-)-6 showed potent cytotoxicities against a colon cancer cell line HCT116 with IC₅₀ values of 2.60, 7.02, 1.47, 3.37, and 4.14μM, respectively, which were better than the standard control doxorubicin (IC₅₀ 9.74μM).