Quantum chemistry and QSAR of antimalarial artemisinin and its derivatives

Abstract

The quantitative structure-activity relationships (QSAR) of 104 antimalarial artemisinin and its derivatives were studied. All compounds were geometrically optimized at the HF/3-21G level. Teh activities measured against 2 different strains of malarial parasites, D-6 and W-2, were used. Models with good to excellent predictive ability were obtained from traditional QSAR method for both activities. The models were shown to predict activities of compounds in the test set very close to the experimental values. However, the derived CoMFA (3D-QSAR) models have only low to moderate predictive power since this method can not explain interactions in heme-artemisinin complex. Therefore, the mechanism of action of these compounds was investigated by means of molecular docking and quantum chemical calculations using the IMOMO(B3LYP/6-31G**:HF/3-21G) method. The obtained results reveal that Fe2+ approach artemisinin compounds at the O1 atom more preferably than the O2 atom. Moreover, we discovered that the high activity compounds have significantly different energy profiles in the reaction mechanism from the low activity compounds. Finally, information on how to enhance the activities were suggested.