Key Parameters Analysis and Regulation of Singlet Oxygen Quenching Rate of Carotenoids

28 kinds of carotenoids are studied to reveal the key parameters and regulation on the singlet oxygen quenching rate. First, the quantum chemistry parameters of carotenoids calculated by Gaussian software combined with substitution parameters were used to construct the quantitative structure-activity relationship model (QSAR) of the singlet oxygen quenching rate of carotenoids. The key parameters affecting the antioxidant activity of carotenoids are revealed, and the data predicted via the QSAR model were provided for subsequent research. Then, a three-dimensional (3D) pharmacophore model was used to regulate and modify the antioxidant activity of carotenoids. The correlation coefficients of the modeling group (R-2) and verification group (Re-pre(2)) of the established QSAR model were 0.945 and 0.916, respectively, which can be used for the analysis of antioxidant activity of carotenoids; the antioxidant activity of carotenoids can be significantly regulated by the number of conjugated C=C bonds, the energy difference between frontier molecular orbitals and the partial Mulliken charge in C1 and the pi center dot center dot center dot pi* excitation energy E(s); the antioxidant activity of carotenoids can be effectively regulated by the hydrogen bond acceptor pharmacophores on both sides of the conjugated C=C bonds and the hydrophobic groups on the conjugated C=C bond; the hydrophobic substituents attached to conjugated C=C bonds can effectively improve the singlet oxygen quenching rate of carotenoids.