Antimutagenic activity of Lutein--an oxycarotenoid present in the macula and its inhibition of cytochrome P 450 enzymes in vitro.

Carotenoid lutein was investigated for its antimutagenic activity in vitro by Ames test using Salmonella typhimurium strains TA 98, TA 100, TA 102 and TA 1535. Mutagens used were direct acting mutagens such as sodium azide (NaN3) (5μg/ plate), nitro-o- phenylendiamine (NPDA) (20μg/ plate), N-methyl- N’-nitro-N-nitrosoguanidine (MNNG) (1μg/ plate), tobacco extract (50mg/ plate) and acetamidofluorene (AAF) (20μg/ plate) which needed microsomal activation. Lutein significantly inhibited the mutagenicity produced by direct acting mutagens as well as mutagens needing activation by cytochrome P450 enzymes at very low concentration (IC50 < 50 μg/plate). Lutein also inhibited the mutagenicity induced by tobacco extract (IC50 < 50 μg/plate). Cytochrome P 450 enzymes which are involved in the activation of several biological agents were found to be inhibited by lutein. Results indicated that strong antioxidant activity of lutein as well as inhibition of carcinogen metabolisom enzymes are the major reason for the inhibition of mutagenicity by this oxycarotenoid.