Assay-guided fractionation of the EtOAc soluble fraction of the rhizomes of Curcuma longa furnished three DPPH free radical scavenging diarylheptanoids, curcumin (1), demethoxycurcumin (2), and bisdemethoxycurcumin (3). Compounds 1-3 showed the DPPH radical scavenging effects with IC(50) values of 2.8, 39.2, 308.7 microM, respectively. L-Ascorbic acid and resveratrol as positive controls exhibited IC(50) values of 22.5 and 25.0 microM, respectively. Compounds 1-3 showed significant hepatoprotective effects on tacrine-induced cytotoxicity in human liver-derived Hep G2 cells. The EC(50) values of 1-3 are 86.9, 70.7, and 50.2 microM, respectively. Silybin (EC(50) = 69.0 microM) and silychristin (EC(50) = 82.7 microM) were used as positive controls.

Bioassay-guided fractionation of the H(2)O extract of the seeds of Psoralea corylifolia furnished one hepatoprotective compound, bakuchiol (1), together with two moderately active compounds, bakuchicin (2) and psoralen (3), on tacrine-induced cytotoxicity in human liver-derived Hep G2 cells. The EC(50) values of compounds 1 - 3 are 1.0, 47.0, 50.0 microg/ml, respectively. Silymarin as a positive control showed the EC(50) value with 5.0 microg/ml.

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Bioassay-guided fractionation of the EtOH extract of Cnidium monnieri (Apiaceae) furnished two hepatoprotective sesquiterpenes, torilin (1) and torilolone (2), together with a new derivative, 1-hydroxytorilin (3). Compounds 1 and 2 showed hepatoprotective effects on tacrine-induced cytotoxicity in human liver-derived Hep G2 cells. The EC50 values of compounds 1 and 2 were 20.6 +/- 1.86 (P < 0.01) and 3.6 +/- 0.1 (P < 0.01) microM, respectively. Silybin as a positive control showed an EC50 value of 69.0 +/- 3.4 microM.

No abstract