Carrageenans: Biological properties, chemical modifications and structural analysis – A review

Carrageenans are sulphated linear polysaccharides of d-galactose and 3,6-anhydro-d-galactose extracted from certain red seaweeds of the Rhodophyceae class. They have been extensively used in the food industry as thickening, gelling and protein-suspending agents, and more recently by the pharmaceutical industry as excipient in pills and tablets. Besides the well-known biological activities related to inflammatory and immune responses, carrageenans are potent inhibitors of herpes and HPV viruses and there are indications that these polysaccharides may offer some protection against HIV infection. Thus, this review describes important aspects of carrageenans related to their industrial/therapeutic applications, physicochemical properties and structural analysis. Moreover, chemical modifications of carrageenans that can lead to prototypes with potential application for the treatment of several diseases, such as herpes, HPV and AIDS, will be outlined.