Anti-microbial and anti-inflammatory studies of Zinc-Salen complex

Abstract

There is much traction about Schiff base metal complexes because of their structural versatility, potentials in bioactivities etc. Thus, N,N′-bis (salicylidene) ethylenediamine - a salen ligand- was synthesized from salicylaldehyde and ethylenediamine; then followed by coordination with zinc(II) to form a Zn–salen complex. The yields of the salen and its zinc complex were 81 ± 2% and 73 ± 2%, respectively. These samples were characterized by melting/decomposition point analyses, solubility tests, Fourier-transform infrared (FTIR) and UV–Visible absorptions. From the results of FTIR, there were evidence for azomethine linkage and Zn complexation because of the characteristic shift of the C=N stretching vibration and deprotonation of the phenolic O–H group. UV–Visible analyses showed π→π* and n→π* transitions of the salen, along with a salen-to-metal charge transfer band in the Zn–salen complex at 350 – 420 nm. These are reasonable features implying coordination between the Zn ion and the base. Melting point of 128 ± 2 for the salen ligand was obtained, indicating high purity. On the other hand, the Zn–salen complex showed lower melting point as compared to other reported analogues. The Zn-salen was lipophilic than the free salen based on the solubility results. The Zn–salen complex gave generic antibacterial activities against Gram-positive, Gram-negative, and fungal strains. In vitro anti-inflammatory assessment showed moderate COX-1 and COX-2 inhibition. And Zn-salen gave higher COX-2 selectivity compared to ibuprofen. These findings implied Zn–salen has potential for the development of novel antimicrobial and anti-inflammatory agents, necessitating detail pharmacological investigations.