knipholone and Carcinoma--Squamous-Cell

The roots of Bulbinella floribunda have been analyzed for the phenolic constituents, resulting in the isolation of five new phenylanthraquinone glycosides, named bulbinelonesides A-E (1-5), along with two known phenylanthraquinones, (+)-M-knipholone (6) and (+)-M-isoknipholone (7). The structures of the new compounds were determined on the basis of extensive spectroscopic analysis, including 2D NMR, and the results of enzymatic hydrolysis. Although the new compounds 3-5, whose absolute stereochemistry of the unsymmetric biaryl moiety was determined to be P by the CD spectrum, did not show apparent cytotoxicity against cultured HSC-2 tumor cells and HPC normal cells, the new compounds 1 and 2, as well as the known compounds 6 and 7, whose biaryl bond was assigned as M, exhibited a tumor-specific cytotoxicity against HSC-2 cells comparable to or slightly weaker than etoposide, used as a positive control.

Topics: Anthraquinones; Antineoplastic Agents, Phytogenic; Carcinoma, Squamous Cell; Cells, Cultured; Circular Dichroism; Drug Screening Assays, Antitumor; Glycosides; Humans; Inhibitory Concentration 50; Japan; Liliaceae; Molecular Structure; Nuclear Magnetic Resonance, Biomolecular; Plant Roots; Plants, Medicinal; Stereoisomerism; Tumor Cells, Cultured