Chemical structure and antioxidant activity of cephalopod skin ommochrome pigment extracts

Significant opportunities exist in the use of seafood by-products to create new beneficial products. Moreover, cephalopod skin is a good source of bioactive compounds. The present study compares the chemical structure properties and antioxidant activity of pigments extracted from the skin of Octopus vulgaris (OVS) and Dosidicus gigas (DGS) with methanol-HCl (T1) and ethanol-HCl (T2). The solubility and spectroscopic analysis (UV-Vis and 1H NMR) indicated that extracted pigments belonged to the ommochrome family. Xanthommatin, dihydroxanthommatin, and kynurenine compounds were identified in the extracts using correlated homonuclear spectroscopy (COSY). The results showed that OVS yielded a higher recovery rate of pigments with antioxidant activity (DPPH, ABTS, and FRAP) than DGS in both solvents. T1 extracted the highest level of antioxidant pigments. The kynurenine proportion and proton peaks observed at 3.0-5.0 ppm (amino-aromatics) in the 1H NMR spectra may explain the differences in antioxidant activity of OVS and DGS.

Automated summary

The chemical structure properties and antioxidant activity of pigments extracted from the skins of Octopus vulgaris and Dosidicus gigas using methanol-HCl and ethanol-HCl were compared. Octopus vulgaris yielded a higher recovery rate of pigments with antioxidant activity, and methanol-HCl extracted the highest level of antioxidant pigments.