Assessment of bioactive compound from microalgae and cyanobacteria

Abstract

Microalgae and cyanobacteria are groups of microorganisms that have been highly exploited due to the presence of various biocompounds which may be used in several biological applications related to health benefits. In this sense, the aim of this work was to evaluate the profile of carotenoids and the antioxidant potential of carotenoid extracts from microalgae Scenedesmus obliquus and cyanobacteria Phormidium autumnale. Microalgae were cultivated in photobioreactor operating in intermittent regime, fed with 2.0L of BG11 medium. The carotenoids were exhaustively extracted from the freeze-dried sample with ethyl acetate and methanol and were determined by high performance liquid chromatography coupled to photodiode array and mass spectrometry detectors (HPLC-PDA- MS/MS) using a C30 column. The antioxidant potential of carotenoid extracts was measured by determination of total oxygen radical absorbance capacity (ORAC) for lipophilic samples. A total of 20 different carotenoids were separated in the extracts of Scenedesmus obliquus and 24 compounds in Phormidium autumnale, representing a total carotenoid content in the extracts of 2650.70μg/g, and 714.3μg/g, respectively. The major carotenoids identified in the two biomass were all-trans-β-carotene (778.1μg/g; 225.44μg/g), followed by all-trans-lutein (746.9μg/g; 117.56μg/g) and all-trans-zeaxanthin (262.5μg/g; 88.46μg/g). The carotenoid extracts show antioxidant capacity, with values of 1779μmol trolox/g (dry wt) for Scenedesmus and 615.7μmol trolox/g (dry wt) for Phormidium. Based on these results, we observed the excellent potential of the Scenedesmus obliquus microalgae for the production of natural carotenoids, as well as a relevant contribution to the oxygen radical absorbance capacity in biological systems when compared to the cyanobacteria Phormidium autumnale.