Five compounds were isolated from the chloroform-soluble fraction of the methanolic extract of the dried rhizomes of Zingiber officinale (Zingiberaceae) through repeated column chromatography. Their chemical structures were elucidated as 4-, 6-, 8-, and 10-gingerols, and 6-shogaol using spectroscopic analysis. Among the five isolated compounds, 6-shogaol exhibited the most potent cytotoxicity against human A549, SK-OV-3, SK-MEL-2, and HCT15 tumor cells. 6-shogaol inhibited proliferation of the transgenic mouse ovarian cancer cell lines, C1 (genotype: p53(-/-), c-myc, K-ras) and C2 (genotype: p53(-/-), c-myc, Akt), with ED(50) values of 0.58 microM (C1) and 10.7 microM (C2).

The methanolic extract of the roots of Polygonum multiflorum (Polygonaceae) was found to show inhibitory activity towards farnesyl protein transferase (FPTase). Bioassay-guided fractionation of the methanolic extract resulted in the isolation of two anthraquinone glycosides, as inhibitors of FPTase. These compounds inhibited the FPTase activity in a dose-dependent manner.