Macroalgae have been regarded as a natural food source since ancient times, their nutritional value being not only proven by recent studies, but also triggering further in-depth research efforts on the matter. The present study aims to provide an insight into the nutritional potential of selected red seaweed species collected in central Portugal by specifically comparing the moist yield and ash content, crude protein, total lipids, carbohydrates and pigment content between species and, ultimately, finding out if there are differences between taxa. The results obtained highlighted the most nutritionally appealing species, namely, Plocamium cartilagineum with respect to protein content (23.18% dw) and Sphaerocococcus coronopifolius with respect to carbohydrate content (40.23% dw), while none of the species studied showed a lipid content higher than 1.80% dw. Regarding pigment content, the highest concentrations of phycoerythrin, carotenoid and chlorophyll a were obtained, respectively, from P. cartilagineum (0.09 mg.mL−1), Porphyra umbilicalis (1.88 µg.g−1 fw) and Jania rubens (38.41 µg.mL−1). We concluded that there are significant differences between the species studied regarding their nutritional profile, with a marked difference between Corallinales and all other species not belonging to this order; regarding pigment content, this variation between orders was not observed. Nevertheless, all the studied species may act as promising complements in a human healthy diet.

Throughout the ages, macroalgae have provided humankind with elements beneficial to human health, and often with bioactive abilities. Yet, while today we fully acknowledge such potential, especially that of the most widely known species, an even greater number of species remain unaknowledged. This holds particularly true for the highly diverse phylum Rhodophyta (red seaweeds) and, therefore, the present study aims to unveil the antioxidant and the antimicrobial potential of twelve red seaweed species collected in central Portugal. Results obtained from the antioxidant assays ABTS and TPC highlighted the high scavenging capacity of the coralline algae Corallina officinalis, Ellisolandia elongata and Amphiroa rigida, and the high phenolic content of Porphyra umbilicalis, whereas the antimicrobial analyses through MIC determination emphasized the activities of Sphaerococcus coronopifolius and Mesophyllum lichenoides against, respectively, Bacillus subtilis and Saccharomyces cerevisiae. This study raised awareness of the bioactive potential waiting to be discovered regarding less known Rhodophyta species, such as Amphiroa rigida and Mesophyllum lichenoides. Therefore, we believe this study provides extra steps in pinpointing Rhodophyta species with bioactive potential, encouraging further studies tailored toward a biotechnological perspective, and, ultimately, influencing current perspectives regarding the exploration of seaweeds.

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