A pair of new enantiomers of xanthones from the stems and leaves of Cratoxylum cochinchinense

BACKGROUND: The simple and caged xanthones from Clusiaceae showed significant antineoplastic activity. This study aims to identify structural diverse xanthones and search for novel antitumor natural products from this family plants. METHODS: The structures of new compounds 1a and 1b were elucidated mainly through comprehensive NMR and MS spectroscopic data, and their absolute configurations were determined by the comparison of the experimental and calculated electronic circular dichroism. RESULTS: A pair of new xanthone enantiomers, (+)- and (−)-cracochinxanthone A (1a and 1b), along with thirty known analogues (2–31), were isolated from extracts of the stems and leaves of C. cochinchinense. Preliminary biological assay of some isolates against HL-60, PC-3, and MDA-MB-231 cancer cell lines. CONCLUSION: Some isolated xanthones exhibited high sensitivity against three human malignant cell lines and the structure–activity relationship study showed that the prenyl and geranyl units may play an important role in antitumor activity. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s13020-019-0235-z) contains supplementary material, which is available to authorized users.