Efficient extraction of hydrophilic and lipophilic antioxidants from microalgae with supramolecular solvents

Abstract

There is strong evidence that lipophilic and hydrophilic antioxidants interact in vivo through different mechanisms and that it is their mixed effects what leads to health benefits. Simultaneous extraction of both types of antioxidants from biomass using organic solvents is inefficient because extraction yields for these phytochemicals are highly dependent on the polarity of the solvent. In this work, we firstly propose the use of supramolecular solvents (SUPRAS) as an innovative approach for the simultaneous extraction of a wide polarity range of antioxidants. Different SUPRAS compositions were investigated for extraction of the total content of carotenoids and polyphenols, as representatives of lipophilic and hydrophilic antioxidants, respectively. Under optimal conditions, antioxidants were extracted from freeze-dried biomass of Scenedesmus sp. in an excellent rate related to their total content (up to 1 mg carotenoids/g dw and 10 mg of gallic acid equivalents, GAE/g dw). Screening based on liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) revealed that lutein was the major carotenoid and caffeic acid the main phenolic compound. The SUPRAS extracts showed high antioxidant activity (25.04 ± 0.73 µM ascorbic acid equivalents antioxidant capacity, AAAC/g dw and 17.02 ± 0.45 µM AAAE/g dw for ABTS and DPPH assays, respectively). SUPRAS offered advantages in terms of non-toxicity, rapidity (5 min extraction) and cost-effectiveness (room temperature, atmospheric pressure) for the recovery of antioxidant compounds from algal biomass and constitute a good alternative to the use of conventional solvents.