Theoretical studies on the structures and chemical properties of catechins

Abstract

Catechins are antioxidants. catechins display anticancer activity, too. Recently, Kuzuhara et al. reported that epigallocatechin gallate (EGCG) binds both DNA and RNA molecules. Their experiments revealed that the branching structure of catechin, consisting of galloyl and catechol groups, is necessary for the interaction between DNA and catechin. In this work, we study the interaction between catechin and DNA (RNA) theoretically. Ab initio molecular orbital calculations are performed for EGCG with bases (9-methyladenine (9-MA), 1-methylcytosine (1-MC), 9-methylguanine (9-MG), 1-methylthymine (1-MT) and 1-methyluracil (1-MU)). We obtained an optimized structure for the complex of EGCG and 9-MG. We also obtained two kinds of optimized structures for the complex of EGCG and 1-MT. It was shown that the main interaction between EGCG and a base is hydrogen bonds. The stabilization energy (SE) for the complex of EGCG and 9-MG is -34.33 kcal/mol and the SE for the complex of EGCG and 1-MT is -29.95 kcal/mol. These are compared with the SEs for the Watson-Crick base-pairs. SE for A-T pair is -23.13 kcal/mol and SE for G-C pair is -40.00 kcal/mol.