Antimicrobial investigation of novel multi-metal complexes of schiff base series

Schiff base complexes are highly potential candidates for new antibacterial agents. Novel free Schiff base ligands (POI & PII) as well as hydrazide-derived Schiff base metal complexes (NiL2 & CoL2) were synthesized by the students from Faculty of Applied Sciences, UiTM Shah Alam. The synthesized free Schiff-base ligands and the Schiff-base metal complexes were screened in vitro for their potential antibacterial activiy against a Gram-negative bacteria strain, Pseudomonas aeruginosa (A TCC 9721 ™) and Gram-positive bacteria strain, Bacillus subtilis (ATCC® 2385f'"). All the test samples were tested to determine their minimum inhibitory concentration (MIC) and to investigate their antimicrobial sensitivity. As compared to the free Schiff base ligands, Schiff base metal complexes showed slightly lower MIC value and greater inhibition zone when tested against B. subtilis (ATCC® 2385f'"). However, there is no inhibition zone observed when both, free Schiff base ligands and Schiff base metal complexes tested against P. aeruginosa (ATCC® 9721 ™). This indicates that Schiff base metal complexes have higher antibacterial activity against Gram-positive strain than Gram-negative strain. A comparative measure on the inhibition zone showed that Schiff base metal complexes have smaller inhibition zone as compared to commercialized antibiotic, Gentamycin. Further studies are needed to investigate the underlying mechanism of bacterial inhibition and toxicity of the Schiff base metal complexes.