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Evaluation of antioxidant activity of three different brown macroalgae by implementing electrochemistry and spectrophotometry: Correlation and future prospects

In this study, a comprehensive evaluation of the antioxidant activity of three brown macroalgae Dictyota dichotoma, Dictyota fasciola, and Halopteris scoparia from the Adriatic Sea (Croatia) by im- plementing electrochemical and spectrophotometrical measurements was performed. The aim was to find out if the used methods correlate with each other to obtain information about the present antioxidant activity. The samples were subjected to fractionation by solid-phase extraction (SPE) which allowed the separation of different polarity compounds. Voltammetry of microfilm immo- bilized on a glassy carbon electrode using square-wave voltammetry (SWV) was applied as an electrochemical method, and the obtained results were correlated to the results of four spectro- photometric methods, namely the reduction of the radical cation (ABTS), the 2, 2-diphenyl-1-picryl-hydrazyl (DPPH) assay, the Folin–Ciocalteu, and the oxygen radical ab- sorbance capacity (ORAC) assay. All methanolic fractions from three brown macroalgae showed higher antioxidant activity than the dichloromethane fractions. The highest activity was obtained for H. scoparia methanolic fraction with an IC50 concentration of 1.947 mg/mL. It was found that antioxidant activity obtained by SWV only correlates well to 1, 1-diphenyl-2-picrylhidrazine (DPPH) radical assay (R2 = 0.83, p < 0.05), while a good correlation was found between ABTS and ORAC assays (R2 = 0. 0.94, p < 0.05). Correlations indicate that the synergistic effect of different compounds extracted from the samples impacted their antioxidant response. All three researched brown macroalgae have shown to be a potent source of natural antioxidants that could further be used in the research of oxidative stress-related diseases.

Brown seaweeds ; Marine organisms ; Voltammetry ; Extraction ; Bioactivity

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