Anthraquinone-benzisochromanquinone dimers from the stems and leaves of Berchemia polyphylla

Three new anthraquinone-benzisochromanquinone dimers polyphylldiquinones A-C (1-3), along with three known analogs floribundiquinone A-B (4-5) and 7-dehydroxyventiloquinone H (6), were isolated from the stems and leaves of Berchemia polyphylla. The chemical structures and absolute configurations of these compounds were determined using HR-ESI-MS, spectroscopic data, and electronic circular dichroism. Notably, compounds (1-5) are dimeric quinones that share the same benzisochromanquinone moiety, specifically identified as 7-dehydroxyventiloquinone H (6), which was the first time to report as a natural product. Compounds 1-2 and compounds 4-5 are two pairs of atropisomers respectively.