Antioxidant properties of different strains of Kappaphycus alvarezii (Rhodophyta) farmed on the Brazilian coast

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.

KEYWORDS:

• Antioxidant potential
• Biological activity
• Functional ingredient
• Phenolic compounds
• Seaweed

Acknowledgements

The authors thank Valéria C. Gelli, Ph.D., researcher from the Fisheries Institute, North Coast Research and Development Center of the Secretariat of Agriculture and Supply of the State of São Paulo, for providing samples of macroalgae.

Supplementary material

Supplemental data for this article can be accessed on the publisher’s website.

Additional information

Funding

PGA thanks the Coordination for the Improvement of Higher Education Personnel (CAPES) – Finance Code 001 – for the postdoctoral fellowship. FC and MTF thank the National Council for Scientific and Technological Development (CNPq) for the productivity fellowship (Proc. 303937/2015-7 and Proc. 304899/2017-8, respectively). This work is part of the international research project BMBF 031B0284 (023/IVV-113816).