Isolation and characterization of bioactive polymer from cuttlebone of Sepiella inermis functions to inhibit the oxidation processes

The growing demand for environmentally safe and biocompatible antioxidants has prompted the search for natural alternatives to synthetic substances. In response, this work aims to isolate and characterize a bioactive polymer (chitosan) isolated from Sepiella inermis cuttlebone, with the purpose of determining its efficacy in alleviating oxidative stress. The polymer's structural, morphological, and crystalline characteristics were assessed using Fourier-transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), and X-ray diffraction (XRD). FTIR indicated the existence of functional groups such as hydroxyl, amine, and carbonyl, which are known to contribute to antioxidant activity. FESEM revealed a rough, porous surface architecture, while XRD indicated a semi-crystalline structure suitable for bioactivity. Functional tests examined the antioxidant and metal-chelating properties in direct comparison with established controls. In the DPPH assay, the polymer’s concentration-dependent radical scavenging activity ranged from 18.4 % to 71.2 %, whereas ascorbic acid showed higher scavenging rates across the same concentrations. Superoxide radical scavenging by the polymer varied from 12.6 % to 65.3 %, but α-tocopherol consistently demonstrated greater effectiveness. For ferrous ion chelation, the polymer’s activity increased from 15.8 % to 68.7 % but remained lower than that of EDTA at all tested concentrations. Although the polymer’s antioxidant and chelating activities did not surpass those of these standard antioxidants, it still exhibited notable bioactivity. Its marine origin, favourable biocompatibility, and customizable structure make it an attractive choice for usage in nutraceuticals, cosmeceuticals, and biodegradable packaging. This study contributes to the growing field of marine biopolymers and emphasizes the necessity of future research on synergistic formulations and in vivo applications.