Synthesis and biological evaluation of Schiff bases and azetidinones of 1-naphthol

INTRODUCTION: Schiff bases and azetidinones form an important structural class possessing wide spectrum of biological activities that include antibacterial and antifungal activity. A series of Schiff's bases N’-(substituted benzylidene)-2-(naphthalen-1-yloxy) acetohydrazides (3a-f) and azetidinones N-[3-chloro-2-oxo-4-(substituted phenyl)-azetidin-1-yl]-2-(naphthalen-1-yloxy) acetamides (4a-b) were synthesized and tested for antimicrobial activity. MATERIALS AND METHODS: The chemical structures of synthesized compounds were elucidated on the basis of IR and 1H NMR spectroscopy. The synthesized compounds were screened for antibacterial activity against E. coli (ESS 2231) and B. subtilis (MTCC 441). The compounds were also tested for antifungal activity against A. niger (NCIM 618) and C. albicans (NCIM 3557) by the cup diffusion method. RESULTS AND DISCUSSION: The in vitro antimicrobial activity results showed that the N-[3-chloro-2-oxo-4-(4-substitutedphenyl)-azetidin-1-yl]-2-(naphthalen-1-yloxy) acetamides (4a-b) exhibited better antibacterial activity than the synthesized N′-(substituted benzylidene)-2-(naphthalen-1-yloxy)-acetohydrazides (3a-f). Compound (4b) displayed potent antibacterial activity against the B. subtilis and E. coli (MIC values of 16-64 μg/mL). The antifungal activity of the synthesized compounds (3a-f and 4a-b) against the A. niger and C. albicans was relatively weak, most of the compounds showed poor activities (MIC >128μg/mL). CONCLUSION: The antibacterial activity of the synthesized compounds was moderate to low and antifungal activity was relatively weak. Therefore, a further study with this class of compounds is necessary to elucidate the mechanism and structure activity relationship.