QSAR Studies of the Antifungal Activities of α-Diaminophosphonates Derived from Dapsone by DFT Method

This QSAR study focused on a series of α-diaminophosphonates derived from Dapsone. Three models have been obtained by taking into account both molecular descriptors and antifungal activities such as those of Aspergillus niger, Aspergillus foetidus and Fusarium oxysporum. Quantum chemistry methods were used at B3LYP/6-31G (d) calculation level to obtain the molecular descriptors. The statistical indicators of the first model which talk about Aspergillus niger activity are: the determination coefficient R2 = 0.976, the standard deviation S = 0.034, the Fischer test F = 80.857 and the correlation coefficient of the cross-validation Q2CV = 0.975. Those of the second model which highlight Aspergillus foetidus activity are: regression coefficient R2 = 0.946, standard deviation S = 0.041, Fischer test F = 35.353 and cross-validation correlation coefficient Q2CV = 0.943. The statistical indicators of the third model are: the determination coefficient R2 = 0.931, the standard deviation S = 0.065, the Fischer F = 27.043 and the correlation coefficient of the cross-validation Q2CV = 0.926. This last model talks about Fusarium oxysporum activity. These models, according to the values of their statistical descriptors, possess good statistical performance. The quantum descriptors such as global electronegativity (χ), the energy of the highest occupied molecular orbital (EHO) and electronic energy (e0) are responsible for the biological activities of the studied Dapsone derivatives. In addition, electronic energy and global electronegativity are proved to be the priority descriptors in predicting the antifungal activities of these Dapsone derivatives. The acceptance criteria of Eriksson et al. used for the test set are verified. The values of the ratio of theoretical and experimental activities for the validation set tend towards unity.