Biphenyls from Berberis koreana.

Three new biphenyls, berbekorin A (1), 2'-hydroxy-3,4,5-trimethoxybiphenyl (2), and 4,5-dihydroxy-3-methoxybiphenyl (3), together with 11 known biphenyls (4-14), were isolated from the n-hexane-soluble fraction of the MeOH extract of the trunk of Berberis koreana. The structures of 1-3 were determined by spectroscopic methods, including 1D and 2D NMR analysis. Compound 1 exhibited cytotoxic activity against the SK-MEL-2 skin melanoma cell line, in particular. Moreover, compounds 2, 5, 6, and 14 inhibited NO production in LPS-activated BV-2 cells, a microglial cell line.