English abstract
Brown seaweeds are very abundant in Oman therefore they are a very valuable source for many ingredients used in food formulations and nutraceutical products. They are rich in polysaccharides which reach up to 76% dry weight; therefore, they were traditionally used to extract functional polysaccharides such as alginate. For maximizing benefits of seaweed after alginate extraction, protein can be extracted as a byproduct with an added value. The present study was conducted to identify the chemical characteristics, functional properties of protein extracted from brown seaweed Sargassum ilicifolium (S. ilicifolium) and its antioxidant potential properties in a rat model of cisplatin-induced nephrotoxicity. For investigation of antioxidant effect of the extracted protein, Sprague Dawely male rats (n=40) were divided into four groups: first group: non-renal oxidative stress control (n=10), second group: renal oxidative stress control (DDP) (n=10), third group: S ilicifolium protein extract solution (n=10), and fourth group: S. ilicifolium protein extract solution with cisplatin (n=10). The nephrotoxicity was induced by a single intraperitoneal injection of DDP (50 mg/kg body weight). Animals were given S. ilicifolium protein solution by oral gavage at Iml/day for a period of 4 weeks. The molecular weight analysis showed presence of six proteins with different sizes: 7.36 x 100 + 0.01, 0.344x 106 +0.01, 0.0373x 106 +0.04, 0.0351x 106 + 0.01, 0.0314 x 106 +0.01, and 0.00420x 106 + 0.03 kDa. The amino acids analysis showed higher non-polar amino acids (59.0 £ 3.19) than polar amino acids (41 $ 3.19). Both the water holding capacity and emulsifying activity of S. ilicifolium protein decreased as pH increased. Both properties were found lower when they were compared with casein. Furthermore, the solubility and foaming capacity of protein extract were almost similar with that of casein. The results showed that the renal oxidative stress control (DDP) group exhibited significant (P< 0.05) elevation in the serum ceratinine and blood urea nitrogen (BUN) accompanied with total antioxidant impairment (TAC) and increasing oxidized Glutathione (GSSG) when compared to non-renal oxidative stress control group. Treatment with S ilicifolium protein showed significant (P < 0.05) positive effect against the oxidative stress associated with cisplatin injection on the TAC, GSSG, BUN, serum ceratinine, and histopathology of kidney of renal oxidative stress rat and therefore, indicated a nephro protective effect of S. ilicifolium protein and its ability to use casein as alternative in food products. Future research is needed to investigate the chemical, functional, antioxidant properties for each fraction of the extracted protein.
