Antimalarial Activity of some Conjugated Arylhydrazones: Ab Initio Calculation of Nuclear Quadrupole Coupling Constants (NQCC)

“Malaria” is a life-threatening blood disease in tropical regions that spreads by the bite of the Anopheles mosquito. Antimalarial medications are designed to cure or prevent this infection, and prosperous achievements in this area mostly depend on the knowing the drug-receptor interactions and active sites of medicine. This improvement can be achieved through understanding the electronic structure of compounds using calculated quadrupolar parameters of nuclei as an efficient theoretical method. In this research, conjugated hydrazones as new antimalarial drugs are investigated to find the correlation between their electronic structures and pharmaceutical behavior. To this aim, the effect of the various substituents and their position on quadrupolar parameters and charge distributions are examined by concepts of nuclear quadrupole resonance (NQR) spectroscopy. The results show that benzothiazole hydrazones are multi-central inhibitors. In addition to the charge density on N13 atom, the presence of two vicinal oxygen atoms with high electron density in the benzene ring has the key role in the iron chelating and consequently antimalarial activity of these compounds. All calculations are performed at the HF/6-31G* level of theory using the Gaussian 03 program.