Optimization of polysaccharides extraction from Pacific oyster (Crassostrea gigas) using subcritical water: Structural characterization and biological activities

Bioactive polysaccharide was extracted from Pacific oyster Crassostrea gigas using subcritical water (SW) and the extraction process was optimize by response surface methodology (RSM). The optimum condition was found to be temperature 125.01 °C, extraction time 14.93 min, and liquid to solid ratio of 44.69:1 (ml:g). At this condition, the yield of the C. gigas polysaccharides (CGPs) was found to be 18.66%. The polysaccharide was characterized for its chemical, physical, thermal, and structural properties using HPLC, GPC, XRD, FTIR, TGA, UV–Vis spectroscopy, and NMR and the results of this characterization showed a characteristic feature of a typical polysaccharide. The CGPs was found to be a D-glucan with α-(1 → 4) configuration. The CGPs was also evaluated for its antioxidant, antihypertensive, and hypoglycemic activity and the IC50 (mg/ml) values were found to be 2.06 ± 0.33, 1.58 ± 0.03, and 2.77 ± 0.01 respectively. The current study demonstrated that SWE could be used as an effective process to extract bioactive polysaccharides from C. gigas.