Antimutagenicity activity of natural xanthophylls against aflatoxin B₁ Salmonella typhimurium

Carotenoids (carotenes and xanthophylls) are excellent antioxidants with antimutagenic and anticarcinogenic properties. They occur naturally in some foods, such as carrots, red tomatoes, butter, cheese, paprika, palm oil, corn kernels, Marigold petals, annatto, and red salmon. In the present study, we used the Salmonella plate incorporation test to examine the effect of xanthophylls extracted from Aztec Marigold (Tagetes erecta) on the AFB₁ mutagenicity, using tester strain YG1024. The effect of lutein on the DNA-repair system in YG1024 was investigated by a pre-incubation test. In a dose-response curve of AFB₁, the mutagenic potency was 1,031 revertants/nmol. The dose of 0.5 μg AFB₁/ plate was chosen for the antimutagenicity studies. Pure lutein and xanthophylls from Aztec Marigold flower (oleoresin and xanthophyll plus) inhibited the mutagenicity of AFB₁ in a dose-dependent manner. The pigments were more efficient at inhibiting the AFB₁ mutagenicity than pure lutein. The percentages of inhibition on AFB₁ mutagenicity were 37, 66, and 76% for lutein, oleoresin, and xanthophyll plus at the dose of 2 μg/plate, respectively. Lutein had a modest effect on the DNA-repair system of YG1024. In spectrophotometric studies, a new absorption peak was detected at 378 nm when lutein and AFB₁ were incubated together, and lutein reacted with AFB₁ metabolites. The results suggest that the inhibitory mechanism of lutein against AFB₁ mutagenicity is most probably the result of a combination of the following events: formation of a complex between lutein and AFB₁, direct interaction between lutein and AFB₁ metabolites, and finally that the lutein may also affect the metabolic activation of AFB₁ by S9 and the expression of AFB₁-modified Salmonella DNA.