Antimutagenicity of xanthophylls present in Aztec marigold (Tagetes erecta) against 1-nitropyrene

The principal natural food colorants used in modern food manufacture are anthocyanins, betalains, carotenoids, chlorophylls, riboflavin and caramel. Carotenoids (carotenes and xanthophylls) occur naturally in some foods such as carrots, red tomatoes, butter, cheese, paprika, palm oil, corn kernels, marigold petals, annatto, and red salmon. Carotenoids (α- or β-carotene and xanthophylls) are excellent antioxidants and inhibit some types of cancers. In the present study, we used the Salmonella typhimurium tester strain YG1024 in the plate-incorporation test to examine the antimutagenicity of xanthophylls extracted from Aztec Marigold (Tagetes erecta) on 1-nitropyrene (1-NP) mutagenicity. Further, we investigated the effect of lutein on DNA-repair system of tester strain YG1024, using a preincubation test. The possible mechanism of lutein on 1-NP mutagenicity was studied by comparing the absorption spectrum of lutein, 1-NP and lutein plus 1-NP. In a dose-response curve of 1-NP, the mutagenic potency was 4 317 revertants/nmol, and the dose of 0.06 μg of 1-NP/plate was chosen for the antimutagenicity studies. Lutein and xanthophylls from Aztec Marigold (pigments for poultry and human use) inhibited mutagenicity of 1-NP in a dose-dependent manner. Lutein and the pigments were not toxic to the bacteria at the concentrations tested (0.002, 0.02, 0.2, 2.0 and 10 μg/plate). The percentages of inhibition of 1-NP mutagenicity were 72%, 92% and 66.2% for lutein (10 μg/plate), pigment for poultry use (10 μg/plate) and pigment for human use (2 μg/plate), respectively. Lutein had no effect on the DNA-repair system of strain YG1024. A new peak was detected at 429 nm when lutein was added at 1-NP, and it was stable throughout the incubation time. The results suggest that the major mechanisms of lutein against 1-NP mutagenicity is the potential formation of a complex between lutein and 1-NP, which could limit the bioavailability of 1-NP.