Extracts from 48 marine macroalgae species (17 Chlorophyta, 8 Phaeophyta and 23 Rhodophyta) from the coasts of Yucatan and Quintana Roo (Mexico) were evaluated for antioxidant activity. The antioxidant activity was measured with the DPPH (2,2-diphenyl-1-picrylhydrasyl) method, and the phenolic content of each extract were also evaluated. All species exhibited a DPPH radical scavenging activity, and three species (Avrainvillea longicaulis, Chondria baileyana and Lobophora variegata) demonstrated great antioxidant potential with very low oxidation index EC 50 (1.44±0.01, 2.84±0.07 and 0.32± 0.01 mg mL −1 , respectively), significantly equivalent to EC 50 of some commercial antioxidants such as α-tocopherol, ascorbic acid, BHA and BHT. Moreover, extracts of the most active species exhibited reducing activities, superoxide anion radical scavenging and inhibition of lipid peroxidation. These results suggest that some macroalgae from the Yucatan peninsula have a great antioxidant potential which could be considered for future applications in medicine, food production or cosmetic industry.

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This study deals with two range-extending brown algae from Tahitian coral reefs, Sargassum mangarevense and Turbinaria ornata; their alginate properties, mannitol and phenolic contents, antioxidant and antimicrobial activities were determined. Turbinaria ornata showed the richest alginate content with the highest extraction yield (19.2± 1.3% dw). Their alginates also exhibited the highest viscosity (50±18 mPa.s), but the M:G ratios (mannuronic acid to glucuronic acid) of alginates (1.25-1.42) were similar in both species. Alginate yield displayed spatial variations, but no significant seasonal changes. The highest mannitol content was found in S. mangarevense (12.2± 2.1% dw) during the austral winter. With respect to other tropical Fucales, both algae exhibited also a high phenolic content (2.45-2.85% dw) with significant spatio-temporal variations. Furthermore, high antioxidant activity and activity against Staphylococcus aureus were also detected in extracts. According to these preliminary results, these two range-extending algae are of key interest in numerous industrial areas.

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