Schistocerca gregaria-derived chitosan: antimicrobial activity and cytotoxicity studies of its Schiff Bases and metal complexes

Abstract

Chitosan prepared by deacetylation of chitin extracted from Schistocerca gregaria (desert grasshopper) has been coupled with different aldehydes to afford the corresponding Schiff bases and consequently reacted with metal (II) salts to provide the corresponding complexes. The compounds were evaluated for their in vitro antimicrobial activity against two Gram positive (Escheria coli and Salmonella typhii), one Gram negative bacterial strains (Staphylococcus aureus), and three fungal strains (Aspergillus niger, Aspergillus flavus, and Tricodma spp). Chitosan and its derivatives were evaluated for their in vitro antimicrobial activity against two Gram positive bacterial (Escheria coli and Salmonella typhii), one gram negative (Staphylococcus aureus) and three fungi (Aspergillus niger, Aspergillus flavus, Tricodma spp) The MIC, MBC, and MFC values revealed that compared to the parent chitosan, the Schiff bases and their complexes have higher antibacterial and fungal activities which are in the order of chitosan metal complexes >chitosan Schiff bases > non-modified chitosan with BMC values of >500, >250 and 125μg/ml respectively, where MIC and MFC results showed similar trend. The cytotoxicity assay using brine shrimps revealed that parent chitosan was the most active against at all concentrations, 10μg/ml, 100μg/ml, and 1000μg/ml compared to chitosan Schiff bases, metal complexes.

Keywords: Antimicrobial activity, Chitosan, Complexes, Desert grasshopper, Schiff bases, Schistocerca gregaria