Pivotal role of curcuminoids on the antimutagenic activity of Curcuma zedoaria extracts

In an investigation of the mutagenic activity of two extracts from rhizomes of Curcuma zedoaria (the mathanolic, CME, and the aqueous, CAE) and antimutagenic activity against mutagens, either 2-amino-3-methylimidazo (4,5-f) quinoline (IQ) or 4-nitroquinoline-N-oxide (4-NQO), in dosages of 1-50 mu g/plate was assayed by using Salmonella typhimurium TA97, TA98, TA100, and TA102 strains. We found that the two extracts showed no mutagenicity when tested with all the tester strains either with or without the S9 mix. Moreover, the two extracts, particularly CME, presented a greater antimutagenicity than CAE did either in IQ or 4-NQO mutagens. However, the inhibition effect on lipid peroxidation was similar with both extracts. The amount of major antioxidants beta-carotene, ascorbic acid, and total polyphenols present in both CME and CAE were similar between each other. In contrast, the content of cucuminoids (44.3 mg/g extract) in CME were only found in small amounts in CAE (0.09 mg/g extract). Consequently, although both of the extracts showed similar antioxidant effects, the curcuminoids, which seem to be the main active principles from this plant, were suggested to play a pivotal role in antimutagenic activity.