Modulation by some natural carotenoids of DNA adduct formation by aflatoxin B1 in vitro.

Nine natural carotenoids have been tested for their ability to modulate formation of DNA adduct by the carcinogen aflatoxin B1 (AFB1) in an in vitro reaction catalyzed by rat liver microsomes. Certain apo-carotenoids, which are precursors of vitamin A, were found to be very efficient in inhibiting the adduct formation. Some other carotenoids, which although have less pro-vitamin A activity, also showed similar inhibitory effect. The DNA adduct formation appeared to be modulated through the action of the carotenoids on microsomal enzymes, since an effective inhibition in each case was observed on the formation of the activated AFB1-metabolite. It is envisaged that such inhibition could form a basis by which natural carotenoids could counteract the carcinogenic action of AFB1.