Molecular Docking and Antibacterial Studies of Pyranopyrazole Derivatives Synthesized Using [Pap-Glu@Chi] Biocatalyst Through a Greener Approach

Abstract

In the present work, papain enzyme was immobilized on a polymer support chitosan through a linkage of glutaraldehyde to form the [Pap-Glu@Chi] biocatalyst through the covalent bonding method. The immobilization of papain on Chitosan was confirmed by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) which revealed the change in morphology of chitosan due to immobilization of papain through glutaraldehyde. Thus prepared heterogeneous biocatalyst was used for the four-component synthesis of pyranopyrazole derivatives by the reaction of substituted aromatic aldehydes, malononitrile, ethylacetoacetate and hydrazine hydrate affording excellent yields within short reaction times at moderate temperature. The catalyst exhibited significant activity up to six cycles. Synthesized compounds were checked for their molecular docking activity using AutoDock Vina against the bacterial protein receptors (PDB code 2VF5 and 1BAG) obtained from the RCSB Protein Data Bank. Significant binding energy values obtained from docking studies revealed good interaction between synthesized compounds and bacterial protein receptor. Synthesized compounds were tested against human pathogenic bacterial strains Escherichia coli, Salmonella typhi, Bacillus subtilis, Pseudomonas aeruginosa along with Gentamicine as a reference antibiotic using disk diffusion method. The compounds were found to exhibit moderate-to-high antibacterial activity.