Chemical characteristics, antioxidant and anticancer potential of sulfated polysaccharides from Chlamydomonas reinhardtii

Abstract

The sulfated polysaccharides (SPs) from Chlamydomonas reinhardtii (Cr) were isolated by hot water method using 80% alcohol and semi purified by anion-exchange column chromatography. The chemical analysis of the extract showed 78% carbohydrates, 18% reducing sugars, 60% non-reducing sugars, 2% protein, 33% sulfate, 39% uronic acid, and 4% ash. The elemental analysis of this C. reinhardtii sulfated polysaccharide-enriched extract (Cr-SPs) showed 53% carbon, 8% hydrogen, and 6% nitrogen. FTIR analysis of Cr-SPs showed characteristic bands of sulfated polysaccharides. Further, the Cr-SPs showed significant hydroxyl radical scavenging activity of 22.29–80.9% at 0.01–1 mg mL⁻¹, 38–77% of DPPH radical scavenging activity at 0.01–1 mg mL⁻¹, 9.8–81% ABTS radical scavenging activity, 34.5–67.6% of ferrous chelating ability, and 11.62–75% of total antioxidant capacity. Cr-SPs also showed efficient in vitro anticancer activity. Specifically, they inhibited triple-negative breast cancer cell (MDA-MB-231) proliferation with an IC₅₀ of 172 μg mL⁻¹. Concentration-dependent reduction in the number of colonies formed by MDA-MB-231 cells suggested their potential to inhibit the clonal expansion of the cancer cells. Higher concentrations of crude extract were found to disrupt the microtubule networks in these cells. The cells treated with Cr-SPs eventually underwent apoptosis as evidenced by the formation of characteristic DNA ladder. These results indicate that Cr-SPs find promising opportunities for cancer treatment.