Optimization and characterization of Kappaphycus alvarezii and κ-carrageenan hydrolysates with potential biomedical applications

Abstract

Kappaphycus alvarezii, a widely cultivated red macroalga, is primarily known as a source of κ-carrageenan (κC), a polysaccharide with potential health benefits. This study optimized the hydrolysis process of K. alvarezii and κC using weak acetic acid under varying conditions of concentration, temperature, and duration. The resulting hydrolysates were characterized and evaluated for their biological activities, including antioxidant properties, α-amylase inhibition, oral sucrose tolerance, cytotoxicity, glucose uptake, and apoptosis gene expression in MCF7 and WiDr cancer cell lines. The optimized conditions—2 M acetic acid at 110 °C for 90 mins—yielded the highest reducing sugar content (31.87 g/L for K. alvarezii and 39.73 g/L for κC). The hydrolysates showed antioxidant activity (IC50: 2.58 mg/mL for K. alvarezii and 4.92 mg/mL for κC), significant α-amylase inhibition, and slightly to moderate toxicity in rats, inducing apoptosis in cancer cells through increased expression of BAX and Caspase 3. In vivo tests further demonstrated the potential of these hydrolysates to modulate blood glucose levels. These findings suggest that K. alvarezii and κC hydrolysates have promising therapeutic applications in antioxidant activity, enzyme inhibition, and cancer treatment, warranting further investigation.