Aflatoxin B1 and DNA Adducts. Proposed Model for Surface Noncovalent and Covalent Complexes with N(7) of Guanine. II.

Abstract

An alternate model for surface noncovalent and surface covalent binding of aflatoxin B1 to N(7) of guanine in DNA is proposed. This model considers the out-of-plane motions of C(8) of aflatoxin B1 in those interactions. The covalent intercalated fit of aflatoxin B1 into DNA arises from steric adjustments made by DNA at the covalent intercalation site as well as local strain in the bond angles about N(7) of guanine and C(8) of aflatoxin B1. The bond angle about N(7) deviates modestly from the sp2 value toward the sp3 value. This study suggests that the surface covalent aflatoxin B1-DNA complex serves only a minor role in aflatoxin's precarcinogenic interaction with DNA and is a likely correctable error.

Aflatoxin Contamination in Foods and Feeds: A Special Focus on Africa

“…The epoxide is a good alkylating agent and can react with bases such as those in DNA and RNA to form the AF-alkylated form. Obviously other factors are involved, as not all alkylating agents are carcinogens and further, AFB 1 has a tendency to specifically attack guanine, one of the four DNA bases (Taylor 1992). Because AFB 1 is somewhat non-polar, it passes though membranes and other lipid barriers easily and also has a slight water solubility so it passes from the aqueous phase at low concentrations and accumulates in fat soluble phases such as adipose tissues.…”