Locating the binding sites of antioxidants resveratrol, genistein and curcumin with tRNA

We located the binding sites of antioxidants resveratrol, genistein and curcumin on tRNA in aqueous solution at physiological conditions using constant tRNA concentration and various polyphenol contents. FTIR, UV-visible, CD spectroscopic methods and molecular modeling were used to determine polyphenol binding sites, the binding constant and the effects of polyphenol complexation on tRNA conformation and particle formation. Structural analysis showed that polyphenols bind tRNA via G-C and A-U base pairs through hydrophilic, hydrophobic and H-bonding contacts with overall binding constants of Kres-tRNA = 8.95(±0.80) × 103 M−1, Kgen-tRNA = 3.07(±0.5) × 103 M−1 and Kcur-tRNA = 1.55(±0.3) × 104 M−1. Molecular modeling showed the participation of several nucleobases in polyphenol-tRNA adduct formation with free binding energy of −4.43 for resveratrol, −4.26 kcal/mol for genistein and −4.84 kcal/mol for curcumin, indicating that the interaction process is spontaneous at room temperature. While tRNA remains in A-family structure, major biopolymer aggregation and particle formation occurred at high polyphenol contents.