Microalga Scenedesmus obliquus: extraction of bioactive compounds and antioxidant activity

ABSTRACT Microalgae have been researched as a sustainable source of bioactive compounds for the food and pharmaceutical industries. The objectives of this work were the extraction and the characterization of fatty acids of Scenedesmus obliquus and to separate, quantify, and evaluate the antioxidant capacity of carotenoids and phenolic compounds of this microalga. The microalga cells were disrupted by using ultrasound. The centesimal composition of lyophilized cells was determined. Fatty acids of the oil were converted into methyl esters and analyzed by gas chromatography (flame ionization detector) to obtain the fatty acid profile. Acetone, petroleum ether, and hexane were the solvents applied to extract the carotenoids and ethanol was used to separate the phenolic compounds. The antioxidant activity of the extracts was determined by the DPPH method. The amount of polyunsaturated fatty acids corresponded to 47.31% of the total for unsaturated, with the predominance of linolenic acid (16.74%) and approximately 9.70% of omega-6. The content of extracted carotenoids was higher by using hexane. Total phenolics concentration of 1.12 g 100 g-1 microalga was found. High percentages of oxidation inhibition were observed for the extracts of carotenoids (>88%) and phenolic compounds (>72%). Therefore, Scenedesmus obliquus presents itself as an alternative, natural, and sustainable source of bioactive compounds.