Chondroitin sulfate from fish waste exhibits strong intracellular antioxidant potential

Abstract

Chondroitin sulfate (CS) is a type of glycosaminoglycan described as an antioxidant molecule that has been found in animal species such as fish. Tilapia (Oreochromis niloticus) represents an eco-friendly source of this compound, since its economical processing generates usable waste, reducing the negative environmental impact. This waste was used for CS extraction, purification, characterization by enzymatic degradation, and evaluation of its antioxidant effect. CS obtained from tilapia presented sulfation mainly at carbon 4 of galactosamine, and it was not cytotoxic at concentrations up to 200 µg/mL. Furthermore, 100 µg/mL of CS from tilapia reduced the levels of reactive oxygen species to 47% of the total intracellular reactive oxygen species level. The ability of CS to chelate metal ions in vitro also suggested an ability to react with other pathways that generate oxidative radicals, such as the Haber-Weiss reaction, acting intracellularly in more than one way. Although the role of CS from tilapia remains unclear, the pharmacological effects described herein indicate that CS is a potential molecule for further study of the relationship between the structures and functions of chondroitin sulfates as antioxidants.

Figure 1. Enzymatic degradation of chondroitin sulfate from tilapia viscera. ΔDi0S: non-sulfated disaccharide; ΔDi4S: disaccharide with sulfation at carbon 4 of galactosamine; ΔDi6S: disaccharide with sulfation at carbon 6 of galactosamine.

Figure 2. Evaluation of the cytotoxicity in RAW 264.7 cell culture. CS-A_tilapia: tilapia chondroitin sulfate; Negative control: cells + culture medium. Data are reported as mean±SE. ^aP<0.01 compared to negative control by ANOVA.

Figure 3. Antioxidant properties of chondroitin sulfate from tilapia viscera. CS-A_tilapia: tilapia chondroitin sulfate; CS_bovine: bovine chondroitin sulfate; Negative Control: cells and culture medium; LPS-Control: cells treated with lipopolysaccharide; AA: ascorbic acid. A, Intracellular reactive oxygen species inhibition tests. B, Hydroxyl radical scavenging. C, Superoxide anion radical scavenging. D, Ferrous ion chelation. Data are reported as mean±SE. Different letters indicate significant differences by ANOVA (P<0.05).