ABSTRACT Kappaphycus alvarezii is one of the most farmed algae globally. It is used almost exclusively for the carrageenan industry, although there is increasing interest in its biotechnological application as a natural product with biological properties. This cultivated species produces different strains with distinct chemical and physiological properties. Despite this, K. alvarezii has been marketed as a single biomass. The aim of this study was to evaluate differences in antioxidant capacities among green, red, brown and G11 strains of K. alvarezii cultivated in southeastern Brazil, assessed by Folin–Ciocalteu reducing potential, DPPH, ABTS and FRAP assay methods. Methanolic and aqueous extracts yielded from 2.67% to 3.43% and 26.25% to 32.90%, respectively. Nevertheless, methanolic extracts showed higher total phenolic content (40.80 mg GAE 100 g−1 DW to 58.49 mg GAE 100 g−1 DW) than aqueous ones (7.77 mg GAE 100 g−1 DW to 12.51 mg GAE 100 g−1 DW), and a similar trend was found for DPPH (7.15% to 31.21%), for ABTS (60.29% to 100.39%), and for FRAP (27.24% to 95.95%). Antioxidant activity of aqueous extracts was lower than 17% for all spectrophotometric assays. The green strain had the highest index of antioxidant capacity, suggesting that this strain may be suitable as a natural source of antioxidants. This is the first report evaluating antioxidant potential of four strains of K. alvarezii, supporting the need for further research to identify and select for its value as a viable natural antioxidant source.

中文翻译：

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巴西海岸养殖的不同菌株 Kappaphycus alvarezii (Rhodophyta) 的抗氧化特性

摘要 Kappaphycus alvarezii 是全球养殖最多的藻类之一。它几乎只用于卡拉胶工业，尽管人们对其作为具有生物特性的天然产品的生物技术应用越来越感兴趣。这种栽培物种产生具有不同化学和生理特性的不同菌株。尽管如此，K. alvarezii 已作为单一生物质销售。本研究的目的是通过 Folin-Ciocalteu 还原电位、DPPH、ABTS 和 FRAP 测定方法评估在巴西东南部种植的 K. alvarezii 绿色、红色、棕色和 G11 菌株之间抗氧化能力的差异。甲醇和水提取物的产量分别为 2.67% 至 3.43% 和 26.25% 至 32.90%。然而，甲醇提取物显示出较高的总酚含量 (40. 80 mg GAE 100 g-1 DW 至 58.49 mg GAE 100 g-1 DW）比水性（7.77 mg GAE 100 g-1 DW 至 12.51 mg GAE 100 g-1 DW），并且发现 DPPH 有类似趋势（ 7.15% 至 31.21%）、ABTS（60.29% 至 100.39%）和 FRAP（27.24% 至 95.95%）。对于所有分光光度测定法，水提取物的抗氧化活性低于 17%。绿色菌株的抗氧化能力指数最高，表明该菌株可能适合作为抗氧化剂的天然来源。这是第一份评估四种 K. alvarezii 菌株的抗氧化潜力的报告，支持进一步研究以识别和选择其作为可行的天然抗氧化剂来源的价值的需要。ABTS（60.29% 至 100.39%）和 FRAP（27.24% 至 95.95%）。对于所有分光光度测定法，水提取物的抗氧化活性低于 17%。绿色菌株的抗氧化能力指数最高，表明该菌株可能适合作为抗氧化剂的天然来源。这是第一份评估四种 K. alvarezii 菌株的抗氧化潜力的报告，支持进一步研究以识别和选择其作为可行的天然抗氧化剂来源的价值的需要。ABTS（60.29% 至 100.39%）和 FRAP（27.24% 至 95.95%）。对于所有分光光度测定法，水提取物的抗氧化活性低于 17%。绿色菌株的抗氧化能力指数最高，表明该菌株可能适合作为抗氧化剂的天然来源。这是第一份评估四种 K. alvarezii 菌株的抗氧化潜力的报告，支持进一步研究以识别和选择其作为可行的天然抗氧化剂来源的价值的需要。