tailieunhanh - Antioxidant properties of folic acid: A DFT study

The main goal of this study is to investigate the antioxidant capacity of folic acid and to elucidate the dominant antioxidant mechanism via H-atom transfer (HAT) and single electron transfer (SET) mechanism. The thermochemical properties including bond dissociation enthalpy (BDE), ionization energy (IE), electron affinity (EA) will be calculated in detail at the B3LYP/6- 311G(d,p) level of theory in the gas phase. In addition, the potential energy surface of reaction between HOO radical with FA will also be established. | Vietnam Journal of Science and Technology 56 4A 2018 39-45 aw ANTIOXIDANT PROPERTIES OF FOLIC ACID A DFT STUDY Nguyen Thi Thuy Nga1 Vu Thuy An2 Dao Duy Quang3 1Department of Pharmacy Duy Tan University 03 Quang Trung Da Nang city 2Department of Environment and Chemical Engineering Duy Tan University 03 Quang Trung Da Nang city institute of Research and Development Duy Tan University 03 Quang Trung Da Nang city Email daoduyquang@ Received 25 July 2018 Accepted for publication 13 October 2018 ABSTRACT Antioxidant activity of folic acid FA was investigated via two main antioxidant mechanisms hydrogen atom transfer HAT and single electron transfer SET by Density Functional Theory DFT at the DFT B3LYP 6-311G d p level of theory. The characterizing thermochemical properties such as bond dissociation enthalpies BDEs ionization energy IE and electron affinity EA were calculated in the gas phase. Analyses of HOMOs distribution show that the positions which easily donate electrons to free radicals are essentially found at C ring while the positions which easily accept electrons LUMOs from radicals are mainly situated at B ring. The lowest BDE values equal to and kcal mol are obtained at C19-H and C9-H position respectively. It is showed that FA represents a potential antioxidant via HAT mechanism. In addition the IE and EA values calculated in the gas phase are equal to eV and eV respectively. This result shows that FA has higher ability to donate electrons into free radicals while the ability to receive electrons is quite weak. Finally the HAT reaction between FA and reactive radical like HOO was also calculated at the same level of theory. This provides more insight into its mechanism on free radicals scavenging. Keywords folic acid antioxidant density functional theory HAT SET. 1. INTRODUCTION Folic acid FA Fig. 1 is one of eight vitamins B that are essential for many bodily functions especially in creating new cells and maintaining them 1 . .