Chitosan extracted from Portunus sanguinolentus (three-spot swimming crab) shells: its physico-chemical and biological potentials

Aim: To summarize the extraction, physio-chemical, antibacterial and antioxidant properties of extracted chitosan from the exoskeleton of three-spot swimming crab, Portunus sanguinolentus as compared to commercial chitosan. Methodology: Chitosan biopolymer was extracted through demineralisation, deproteinization and deacetylation. The physico-chemical characterization of the extracted chitosan was carried out using Fourier Transforms Infrared Spectroscopy (FTIR), Field Emission Scanning Electron Microscopy (FESEM), X-Ray Diffraction (XRD), Thermogravimetric analysis (TGA) and Colorimetric analysis. Antibacterial activity using different concentrations of chitosan against Escherichia coli and Aeromonas hydrophila were tested by disc-diffusion method, while antioxidant activity was estimated by 1,1-diphenyl-2-picrylhydrazyl (DPPH) and H2O2 scavenging assay. Results: Crab chitosan (CC) showed the maximal zone of inhibition (17.00±0.50 and 15.16±0.577 mm), while commercial chitosan (CMC) showed 12.67±0.577 and 14.17±0.288 mm) against E. coli and A. hydrophila respectively. The scavenging potential of extracted chitosan ranged from 14 to 17% at different concentrations (0.05 to 0.2 mg ml-1). Crab chitosan efficiency to scavenge 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals varied from 7.2 to 12.98% at different concentrations (0.05 to 0.2 mg ml-1). Interpretation: Overall, the extracted chitosan exhibited properties to commercial chitosan, suggesting that it could be utilized as a dietary supplement in the fishery sector to protect against bacterial infections. This circular economy approach could significantly benefit sustainable waste management and environmental health. Key words: Antibacterial, Biopolymer, Chitosan, Crab, Portunus sanguinolentus