Preparation and in vivo antitumor activity of κ-carrageenan oligosaccharides

Carrageenan oligosaccharides were produced from the final products of commercial extractions of gelling carrageenan and thickening carrageenan, which were specifically depolymerized by kappa-carrageenase extracted from the marine bacterium Cytophaga MCA-2. The weight-average molecular weights of the two oligosaccharides produced were 681 and 798 Da. The sulfate contents were assayed as 17.2% and 21.8%. Antitumor activities of the oligosaccharides were tested on Sarcoma 180 tumor transplanted in mice. The carrageenan oligosaccharide from the thickening carrageenan product showed much higher tumor inhibition (70.8%) and catalase activity at a dosage of 100 mg kg(-1) compared with the control group. The gelling and thickening carrageenan oligosaccarides could also significantly increase the weight of immune organs such as the thymus, which suggests that the antitumor mechanism of the carrageenan oligosaccharides may be initiated via organ-mediated defense reactions.