New biphenyl compounds with DNA strand-scission activity from Clusia paralicola.

Three new biphenyl derivatives, clusiparalicolines A (1), B (2), and C (3), were isolated from the roots of Clusia paralicola by bioassay-directed fractionation using the DNA strand-scission and the KB human cancer cell line cytotoxicity assays. Compounds 1 and 2 were found to be active in the DNA strand-scission assay, whereas all three compounds exhibited modest cytotoxicity against the KB cell line. The structures of 1-3 were elucidated by spectroscopic methods including 1D and 2D NMR techniques.