A comprehensive review of traditional uses, bioactivity potential, and chemical diversity of the genus Gracilaria (Gracilariales, Rhodophyta)

The genus Gracilaria is an important marine bio-resource since some members are a source of about 80% of the global production of agar. Moreover, species of Gracilaria are used in traditional medicine and human diet in many parts of the world. In this review, it was possible to verify that the number of publications concerning bioactivities for the genus has highly increased, and several promising results in the agriculture and aquaculture fields, as well as antimicrobial, cytotoxic, antioxidant, antinociceptive, anti-ulcer, antidiarrheal, anti-hyperlipidemic, antiacetylcholinesterase, and anti-inflammatory activities, have been reported. However, many bioactivity results are obtained only for the crude extracts and fractions. Phytochemical approaches are uncommon, and the chemical knowledge related to the genus is only available from nutrition, ecology, or physiology fields. The genus contains a wide variety of metabolites, such as mycosporine‑like amino acids (MAAs), agarans, lipids, steroids, diterpenes, phenolic acids, bromophenols, sulfonic acids, oxylipins, heterosides, and pigments. Several of these metabolites are bioactives and of particular interest for industrial and medical applications. In general, the genus Gracilaria has a high potential as a source of high-value compounds and extracts for several applications. However, only agar is commercially exploited. A better use of the biomass from commercial cultivation may be an important alternative for exploiting the other bioactive components. Further studies on the chemical composition and isolation of bioactives in the genus are also required.