Molecular Modelling of Antioxidant Agent by QSAR Study of Caffeic Acid Derivatives

Abstract

Molecular modeling using Quantitative Structure and Activity Relationship (QSAR) has been performed on caffeic acid derivatives which is previously studied as an effective antioxidant agent. This research focuses on a set of experimentally IC50 value data of 4 caffeic acid derivatives. The mathematical method (i.e., multilinear regression calculation) was used to build the QSAR model. QSAR analysis was employed on fitting subset using log (1/IC ) as a dependent variable and atomic net charges aromatic carbons, dipole moment and partition coefficient in n-octanol/water as independent variables. The PM3 method was used to calculate the quantum chemical descriptors, chosen to represent the electronic descriptors of molecular structures. The relationship between log (1/IC50) and the descriptors was described by resulted in the QSAR model. The resulted QSAR model for caffeic acid derivatives as an antioxidant is presented below: -7.858+1.149dipol+0.485logP-61.68C5 R=1; R 50 =0.999; SE=0.008; F=342 QSAR model for caffeic acid derivatives showed the enhancement of antioxidant activity due to the decrease of electronic properties (derived from the dipole moment value and C5 atomic charge), Log P representing hydrophobicity did not show a significant effect on antioxidant activity while increasing the chain length of antioxidant molecules indicate an increase in steric hindrance causes a decrease in antioxidant activity. The calculated PRESS (Predicted Residual Error Sum of Square) value was 6.69E-05, which indicates the calculated log (1/IC50) using QSAR Hansch Model of caffeic acid derivatives is similar with experimental data.