Activity-guided isolation of cytotoxic bis-bibenzyl constituents from Dumortiera hirsuta.

: Activity-guided fractionation of the ether extract of Dumortiera hirsute (Japanese liverwort), using cytotoxicity testing with cultured HL 60 and KB cells, resulted in the isolation of a new cytotoxic bis-bibenzyl compound, along with the two known bis-bibenzyls: isomarchantin C and isoriccardin C. The structural determination of the new bis-bibenzyl through extensive NMR spectral data indicated a derivative of marchantin A, which has been isolated from the liverwort Marchantia polymorpha. The cytotoxicity of the bis-bibenzyls was evaluated by the MTT (3-(4,5-di-methylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay using cultured HL 60 and KB cells.