Computational note on the calculation of the dipole moment, polarizability and hyperpolarizability of solanidine

Abstract

Glycoalkaloids are potentially toxic secondary plant metabolites found in potatoes, tomatoes, and eggplants. The two major potato glycoalkaloids, a-chaconine and asolanine, are trisaccharides or triosides; i.e., they have three carbohydrate groups attached to the 3-position of the aglycone. The mild hydrolysis products of these compounds are the so-called b- and c-chaconines and solanines, with one or two carbohydrates each [1], while solanidine is the steroidal aglycon of these potato glycoalkaloids. These glycoalkaloids are very important precursors for the synthesis of hormones and some pharmacologically active compounds [2]. The objective of this work is to report the results of the calculation of the dipole moment, polarizability and hyperpolarizability of solanidine ((3b)-solanid-5-en-3-ol), by using a new model chemistry within density functional theory (DFT) [3] specially tailored to study heterocyclic systems [4]. The CHIH-DFT has proved valuable for the case of antiparasitic drugs, flavonoids, and organic corrosion inhibitors [4]. The results for the calculation of the total dipole moment l of solanidine and its components calculated with the CHIH(small) model chemistry, together with the values obtained through MNDO, AM1, PM3 and PM5 semiempirical calculations [6,7] are displayed in supplementary Table 1. The label (a) represents the calculation of the dipole moment l on the DFT geometry obtained through the CHIH(small) model, while the label (b) indicates the same calculation but performed on the geometry obtained through the corresponding semiempirical model. The results for the calculation of the average polarizability a of solanidine and its components calculated with the CHIH(small) model chemistry, together with the values obtained through MNDO, AM1, PM3 and PM5 semiempirical calculations [6,7] are displayed in supplementary Table 2. The (a) and (b) labels have the same meaning as for the dipole moments. The results for the calculation of the first order hyperpolarizability btot of solanidine and its components calculated with the CHIH(small) model chemistry, together with the values obtained through MNDO, AM1, PM3 and PM5 semiempirical calculations [6,7] are displayed in supplementary Table 3, with (a) and (b) indicating the calculation on the DFT geometry and on the semiempirical geometry, respectively. In this work, a new model chemistry within DFT (the CHIH chemistry model) has been presented and the methodology has been applied to the study of a molecule which is potentially a very important precursor for the synthesis of hormones and some pharmacologically active compounds. The dipole momentl, the polarizabilitya and the first hyperpolarizability b of solanidine ((3b)-solanid-5-en-3-ol) have been determined by using the CHIH(small) model chemistry. The results of the calculation of the same magnitudes using semiempirical methods on the DFT geometry and on their own geometries have also been displayed. The computational calculation of the dipole moment, polarizability and hyperpolarizability has emerged as a field of intense activity in recent years. This is mainly due to the many important applications in extremely diverse research directions. These include the modeling of pharmacological activity and quantitative structure–activity relationship QSAR studies and the results of this work could be useful in those areas of research. The CHIH-DFT model chemistry appears to be a useful tool for the study of the molecular structure and electronic properties of heterocycles, and further applications to several molecular systems are being pursued in our laboratory.