Teerayut SriyatepCholpisut TantapakulRaymond J. AndersenBrian O. PatrickStephen G. PyneChatchai MuanprasatSawinee SeemakhanSuparerk BorwornpinyoSurat LaphookhieoMae Fah Luang UniversityMahidol UniversityUniversity of WollongongThe University of British Columbia2019-08-282019-08-282018-01-01Fitoterapia. Vol.124, (2018), 34-41187369710367326X2-s2.0-85031744074https://repository.li.mahidol.ac.th/handle/20.500.14594/47339© 2017 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 4.14 μM, respectively, which were better than the standard control doxorubicin (IC50 9.74 μM).Mahidol UniversityPharmacology, Toxicology and PharmaceuticsArticleSCOPUS10.1016/j.fitote.2017.10.009