Brazilian native species of Gracilaria (Gracilariales, Rhodophyta) as a source of valuable compounds and as nutritional supplements

In Brazil species of Gracilaria play a social and economic role in some poor communities of the northeastern coast. Considering that these algae are typically consumed after depigmentation and drying, little is known about the chemical composition and nutritional value after processing. In the present study dried and depigmented samples of Gracilaria birdiae (GB), Gracilaria caudata (GC), Gracilaria domingensis (GD), and a commercially available sample of G. birdiae (C-GB), provided by a local community, were studied as a source of valuable compounds and as nutritional supplements. In nutritional terms, the dietary fiber and mineral contents of the studied algae were higher than those of the traditional foods in the standard Brazilian diet. The results suggest that these algae have functional properties and consequently may be used as a source of nutraceutical. GB and GC showed a high antioxidant potential, similar to that of some staple foods (e.g., cereals and legumes), but lower than that of rich-antioxidant foods (e.g., berries and nuts). The polysaccharides from both G. birdiae samples (GB and C-GB) showed a low sulfation degree and higher yields, suggesting that they are a good source of agar. GB was also rich in mycosporine-like amino acids (MAAs), mainly porphyra-334. In contrast, C-GB contained the lowest values of MAAs and antioxidants. The reduction in these compounds may compromise the use of C-GB for other purposes such as cosmetic production. However, the sample of C-GB showed the highest potential as a source of dietary fiber and agar. In general, the analyzed species are alternatives to traditional foods and a source of valuable compounds.