Rating of Sweetness by Molar Refractivity and Ionization Potential: QSAR Study of Sucrose and Guanidine Derivatives

Abstract

A quantitative structure activity relationship study of 31 sucrose derivatives and 30 guanidine derivatives has been undertaken. Their sweetness values, relative to sucrose (RS), have been taken from literature.  The study has been made with the help of CAChe Pro software by using eight descriptors, viz. electron  affinity, ionization potential, electrophilicity index, total energy, heat of formation, steric energy, molar refractivity and solvent accessible surface area. Multi-linear regression (MLR) analysis has been  performed with different combinations of descriptors and the quality of regression has been adjudged by the correlation coefficient, cross-validation coefficient and other statistical parameters like the standard error, standard error of the estimate, degrees of freedom, etc. The study indicates that ionization potential appears an important descriptor for sucrose derivatives, whereas molar refractivity appears an important descriptor for guanidine derivatives. The ionization potential alone and in combination with the electrophilicity index, molar refractivity and solvent accessibility surface area provide dependable QSARmodels for sucrose derivatives. Molar refractivity alone and in combination with solvent  accessibility surface area, ionization potential and heat of formation provide dependable QSAR models for guanidine derivatives. The predicted sweetness values obtained by these QSAR models are close to observed sweetness.

KEYWORDS: Sweetness, sucrose, guanidine, DFT, PM3.