Investigation of anti-inflammatory and antimicrobial activities of hydrazone-based diorganotin (IV) complexes: Synthesis, spectroscopic characterization, and computational studies

In the search of novel and effective anti-infectious agents, new hydrazone ligands (1-4) and their diorganotin (IV) complexes (5-20) were synthesized by condensing piperonylic hydrazide with salicylaldehyde derivatives, which have been further characterized by numerous physical and spectral techniques [1H, 13C, 119Sn] NMR, mass spectroscopy, UV-Vis, IR). These techniques ascertained dibasic tridentate coupling of hydrazone ligands with diorganotin (IV) through phenolic, enolic oxygens, and imine nitrogen, demonstrating pentacoordinated stereochemistry of the complexes. The thermal stability of up to 160 degrees C of the complexes was ascertained by TGA studies whereas low conductance signified compounds have non-electrolytic nature. Further, the antimicrobial activity was evaluated against four bacterial and two fungal strains by serial dilution assay, which demonstrated that the metal complexes (10, 11, 12) have comparable MIC values (0.0085-0.0098 mu mol/ml) with ciprofloxacin and excellent biological responses in comparison of fluconazole. The phenyl complex [Ph2SnL2] (12) was found to be the most active antimicrobial agent with the lowest MIC value (0.0085 mu mol/ml). The compounds were also screened for in vitro anti-inflammatory activity by BSA denaturation assay and the phenyl complex [Ph2SnL2] (12) has been reported as most potent with 7.62 IC50 value, which is comparable with diclofenac sodium. Further, the biologically active complexes (9-12) and their hydrazone ligand [H2L2] were theoretically analyzed by computational investigations to support the in vitro results. The molecular docking analysis of compounds was performed on the active site of C. albicans (PDB ID: 5V5Z) and E. coli (PDB ID: 1HNJ) to assess the binding interactions and binding energy. The DFT and MESP (2, 9-12) revealed the most reactive areas, molecular geometry, Mulliken atomic charges, electronegativity, etc. of the compounds (2, 9-12). The ADMET profile showed the toxicity level and drug-likeness properties, showing their potential to operate as viable antagonists. Synthesis and characterization of newly synthesized hydrazone-based organotin metal complexes, which were further evaluated by biological and computational studies.image