Biological evaluation, molecular docking and DFT studies of charge transfer complexes of quinaldic acid with heterocyclic carboxylic acid

Abstract

The quinaldic acid based charge transfer (CT) complexes with the ionic counterpart of furan (QCFC), thiophene (QCTC) and pyridine-2-carboxylic acid (QCPC) were prepared and successfully characterized by 1H NMR, 13C NMR, FT-IR spectroscopic techniques. In addition, the QCFC was characterized by Dept-135 and 2D NMR (Cosy, HQSC and HMBC) techniques. The electrical conductivity of synthesized CT complexes has also been investigated. The in vitro anti-inflammatory and antidiabetic activities were studied and the results were compared with reference drugs. The QCFC exhibited better anti-inflammatory and antidiabetic activity than QCTC and QCPC. Good stability under physiological conditions was observed for the CT complexes synthesized. The molecular docking studies were also performed with an α-amylase enzyme (1HNY.pdb) to identify the probable binding site of the complexes. All the CT complexes have similar binding score and the QCFC showed 4 hydrogen bonding interactions with α-amylase enzyme. Also, the 3D structure of the complexes was optimized using the Gaussian09 W program and DFT calculations were performed to find the significant regions that are necessary for enzyme inhibition.