The interaction mechanisms of tetrahydrocurcumin on alcohol dehydrogenase: Insights from enzymatic activity assays, spectroscopic methods and computational techniques

Abstract

Tetrahydrocurcumin (THC), a major metabolite of curcumin, is renowned for its potent antioxidant and anti-inflammatory properties, including preventing liver injury from alcohol. Alcohol dehydrogenase (ADH), an essential enzyme in alcohol metabolism, is significant in the development of alcohol-induced diseases. Hence, enzymatic activity assays, spectroscopic methods, and computational techniques were employed in this study to explore their interaction. The results indicated that THC can competitively inhibit ADH activity, as inferred from the kinetic parameter values. Meanwhile, THC spontaneously entered the substrate-binding cavity of ADH to form a binary complex, and surrounded by Thr178, Leu57, Ile318, Leu141, Glu68, Leu116, Phe93, Val294, and Asp49. The Ka value of this binding was 1.724 ± 0.017 × 104 M−1 at 298 K. This binding process was driven by hydrogen bonds and van der Waals forces; additionally, the π electrons in THC were significant for the stability of the ADH-THC complex. The presence of THC led to a decrease in the α-helix content of ADH, resulting in a looser secondary structure. Furthermore, molecular dynamic simulations revealed that Glu68, Leu116, Phe93, Val294, and Asp49 made significant contributions to the binding process. The inhibition of ADH catalytic activity may be primarily attributed to the interaction between THC and the Val294 residue.