*3.7. Determination of Phenolic Compounds*

Quantification of phenolic compounds was performed according to the Folin-Ciocalteu method [88]. Reaction was performed by adding 20 mg of biomass and placed in an Eppendorf with 1 mL of 80% methanol (Sigma-Aldrich, St. Louis, MO, USA). The solution was stirred and incubated at 4 ◦C in darkness for 12 to 24 h. Following this, the solution was centrifuged at 3500 rpm for 10 min, 4 ◦C. Then, 100 μL of the extract, 700 μL of distilled water, 150 μL of 20% anhydrous sodium carbonate (Na2CO3) (Sigma-Aldrich, St. Louis, MO, USA) and 50 μL of the Folin-Ciocalteu reagen<sup>t</sup> (Sigma-Aldrich, St. Louis, MO, USA) were mixed by stirring and incubated at 4 ◦C in darkness for 2 h. The absorbance was measured at 760 nm using a UV–visible spectrophotometer (SHIMADZU UV MINI-1240, Duisburg, Germany). The blank included all reagents, except the extract that was replaced by 80% methanol. Phenolic contents were determined by constructing a standard curve using di fferent phloroglucinol (Sigma-Aldrich, St. Louis, MO, USA) concentrations. Results were expressed in the mg equivalent of phloroglucinol per g of algal dry weight (DW).
