Microwave-assisted depolymerization of hydrothermally extracted carrageenan from Chondrus crispus

Abstract

Carrageenans, extracted from red macroalgae, have demonstrated to present a wide variety of biological activities, such as antitumor activity, which could be enhanced upon depolymerization techniques. For that reason, this work dealt with the extraction of oligocarrageenans and carrageenan from Chondrus crispus by autohydrolysis, and the evaluation of microwave-assisted depolymerization to evaluate the improvement of its antitumor activity. This activity may be conditioned by the extraction method, the degree of sulfation, or the degree of depolymerization. Hence, these parameters were assessed, revealing an increase on the soluble sulfate content and lower molecular weight after 25 min of processing at 140 or 160 °C. In addition, the extract viscosity was lowered from 10,000 to 100 Pa·s, suggesting a positive effect of the microwave-assisted depolymerization and an enhanced bioavailability. The antitumor activity of the depolymerized oligocarrageenan and carrageenan was studied against human ovarian carcinoma cell line, reaching up to 92 % of cell growth inhibition (IC₅₀ = 84 mg/L).