Microwave hydrogravity pretreatment of Sargassum muticum before solvent extraction of antioxidant and antiobesity compounds

Abstract

BACKGROUND: Microwave hydrodiffusion and gravity (MHG) of Sargassum muticum was proposed both for obtaining an aqueous extract and as pretreatment before ethanol extraction of bioactives. RESULTS: No significant differences in composition and properties between the aqueous phase drained during MHG processing at 600 W/7 min (MHG-1) and at 600 W/5 min + 300 W/5 min (MHG-2) were observed. The aqueous extract, accounting for less than 0.2% of the initial material, was refined by adsorption onto food grade resins to recover and concentrate the phenolic fraction, further eluted in 68% ethanol. The final product contained more than 50% phlorotannins and the antiradical capacity was higher than that of Trolox. Ethanolic extraction of the dried solids yielded 7% non-volatile solubles, containing 5% phenolics and 1.2% fucoxanthin. After 12 months at room temperature in the dark, phenolic and fucoxanthin content, and antioxidant properties of the extracts were markedly reduced. The aqueous extracts from MHG-2 and the ethanolic extracts from the dried solids showed inhibition of lipogenesis in 3TL1 cells when used at 100 µg mL−1. CONCLUSION: MHG processing can be proposed both for the extraction of an aqueous fraction and for the conditioning of seaweed biomass before conventional solvent extraction of bioactives. © 2018 Society of Chemical Industry.