Antimutagenic and anticarcinogenic activity of natural and synthetic curcuminoids.

Five synthetic curcuminoids and three natural curcuminoids were investigated for their antimutagenic and anti-promotional activity. The natural curcuminoids, curcumin I (diferuloylmethane), curcumin II (feruloyl-p-hydroxycinnamoylmethane) and curcumin III (bis-(p-hydroxycinnamoyl)methane) isolated from Curcuma longa were found to be potent inhibitors of mutagenesis and crotean oil-induced tumour promotion. Curcumin III produced 87.6% inhibition to 2-acetamidofluorene (2-AAF) induced mutagenesis, at a concentration of 100 micrograms/plate, curcumin II and curcumin I produced 70.5% and 68.3% inhibition at the same concentration. All the synthetic curcuminoids were found to inhibit 2-AAF-induced mutagenicity among which salicyl- and anisylcurcuminoids were the most active. Curcumin III was the most effective anti-promotor among natural curcuminoids. While 90% of the control animals were having papillomas on the 10th week of tumour initiation, only 10% of the curcumin III-treated animals, 20% of the curcumin II-treated animals, and 40% of the curcumin I-treated animals were having papillomas. Salicylcurcuminoid, which was causing no papillomas by the 10th week, was the most potent anti-carcinogen among the synthetic curcuminoids. Piperonal curcuminoid also exhibited anti-promotional activity.