Dr. P. GanesanPraisy M. ShajuDr. S. David KingstonMr. M. Muruganantham2022-08-102022-08-102021https://krishikosh.egranth.ac.in/handle/1/5810186160Cephalopods represent one of the ocean's greatest potential food resources. In Tamil Nadu, especially, at Thoothukudi coast cephalopod is a pronouncing commodity in foreign exports. They are processed and exported in various forms. The ink, usually discarded as waste can be used as a source for bioactive compounds. Though, there are many reports of bioactive properties in crude ink, as far now there are only a few reports regarding the bioactive properties in melanin and MFI (Melanin Free Ink). The present study investigated the antioxidant of MFI and antibacterial properties of MFI and melanin from three cephalopods such Sepia pharaonis, Sepioteuthis lessioniana and Amphioctopus aegina using in-vitro assays. The melanin and MFI were separated out by ultracentrifuging the crude ink at 50,000 rpm for 1hr at 4°C. The percentage yield of MFI in cuttlefish, squid and octopus were estimated as 64, 68 and 67.5%, respectively and its protein content was recorded as 1.2±.01, 1.04±.03 and 1.52±.01 mg/ml, respectively. DPPH scavenging activity of MFI from S. lessoniana was found to be concentration dependent and had a maximum activity of 17.83±0.84% at a concentration of 0.05 mg/ml. MFI from S. pharaonis and A. aegina showed the highest scavenging activity of 8.19±0.25% and 28.29±0.41% at a concentration of 0.04 mg/ml and 0.045 mg/ml, respectively. MFI from S. pharaonis, S. lessoniana and A. aegina had the highest metal chelating activity of 15.78±0.42, 26.96±0.49 and 47.62±0.48% at a concentration of 0.03, 0.015 and 0.04 mg/ml, respectively. When MFI added with sardine fish mince, it retarded the lipid oxidation during the entire storage period and it was very clear with the lower TBARS values compared to the control. On the 15th day of storage the TBARS values of mince with MFI of S. pharaonis, S. lessoniana, and A. aegina were 3.25±0.05, 3.09±0.05 and 2.83±0.07 mg MAD/kg fish, respectively. These values were lower than 3.62 mg MAD/kg fish, which was the TBARS value of fish mince without MFI on the 3rd day The in vitro antibacterial properties of melanin and MFI were tested against eight human pathogens such as Gram positive strains: Staphylococcus aureus ATCC 25923, Staphylococcus aureus ATCC 11632 and Gram negative strains: Escherichia coli ATCC 25922, Salmonella typhimurium MTCC 98, Salmonella arizonae ATCC 13314, Klebsiella pneumonia ATCC 700603, Pseudomonas aeruginosa ATCC 27853 and Vibrio vulnificus MTCC 1145. Though MFI had no antibacterial activity, melanin from all the three cephalopods showed concentration dependent antibacterial activity against the tested pathogens. Melanin from A. aegina has shown the highest inhibitory activity of 25 mm against Salmonella typhimurium MTCC 98. FTIR analysis revealed the presence of O-H or N-H stretching vibration of carboxylic acid and phenolic in MFI of cephalopods. The spectrum received for melanin revealed its structural similarity with substances such as indole, pyrrole and substituted pyrrole. The present study reveals that MFI from cephalopods possess antioxidant properties and the melanin possess promising antibacterial activity and also suggest that MFI and melanin from cephalopods can be used as a natural source of antioxidant and antibacterial agent, respectively.EnglishThesis