Nyasol is a lignan isolated from Anemarrhena asphodeloides Bunge with potent anti-tyrosinase, antipyretic, cardiotonic, diuretic, antibacterial, and antioxidant activities. In this study, theoretical calculations based on density functional theory (DF...
Nyasol is a lignan isolated from Anemarrhena asphodeloides Bunge with potent anti-tyrosinase, antipyretic, cardiotonic, diuretic, antibacterial, and antioxidant activities. In this study, theoretical calculations based on density functional theory (DFT) using the B3LYP hybrid functional and the 6-311+G(d,p) basis sets were conducted to explain the antioxidant behavior of nyasol. After twenty-four initial structures had been generated by Omega2 and optimized by Gaussian 16, three distinct conformers were selected for further calculations. Electronic property results showed that nyasol has radical scavenging activity and that 4’-OH is more potent than 4-OH. However, nyasol has weaker radical scavenging activity than well-known antioxidants. And, the results obtained by calculation agreed with published experimental data. In addition, three different mechanisms for the antioxidant effect of nyasol, viz., hydrogen atom transfer (HAT), single electron transfer-proton transfer (SETPT), and sequential proton loss electron transfer (SPLET), were studied and compared in the gas phase and ethanol and water medium. The results obtained showed HAT was thermodynamically dominant.