Quantum Chemical Studies on Some Thiosemicarbazone Derivatives as Ribonucleotide Reductase Inhibitor

QSAR analysis of thiosemicarbazone derivatives exposing RNR inhibitory activities [1] was performed for 21 compounds. Among these compounds, 13 of them were reported with inhibitory concentration (IC50) in the l M range. The inhibitory concentration of those compounds was converted into -logIC50 before being correlated with the structural features.

The quantum chemical calculations have been carried out at the B3LYP at Complete Basis set (CBS) level of theory using Gaussian-09 series of program package. The density functional theory (DFT), Becke’s three parameter exchange function along with the Lee–Yang–Parr correlation function (B3LYP) were considered to calculate the quantum chemical descriptors such as HOMO, LUMO, Energy gap, Hardness, Softness, Chemical potential and Dipole moment of the investigated molecules. The variables make a unique statistically significant contribution (p < 0.05). According to their beta values, electronegativity showed the biggest beta coefficient (–13.225). It has been revealed that variable has a unique contribution to a stronger explanation of dependent variables. Beta values for the electrofugality was slightly lower (8.350) , showing least contribution for rest of the elements. Other variables (Energy gap, chemical potential, nucleofugality) measured for this model was statistically significant.