Value-added fermentation of Ecklonia cava processing by-product and its antioxidant effect

The interest in the extraction of polyphenolic compounds from plant materials is focused on upgrading of the large amount of by-products coming from food or cosmetics industries from which the press residues have particularly high contents of phenolics. In this study, for value-added use of the brown seaweed Ecklonia cava processing by-product (ECPB), which can be obtained after polyphenolic extraction of E. cava, it was fermented by the yeast Candida utilis and its antioxidant activities were evaluated by 1,1-diphenyl-2-picrylhydrazyl, hydroxyl, and alkyl radical scavenging using electron spin resonance spectrometer. ECPB was fermented for 1 similar to 4 days prior to being extracted with 80% ethanol, and significant differences were observed in extraction yields, total phenolic contents (TPC), and radical scavenging activities with the fermentation time. Extract from the ECPB fermented for 1 day exhibited the highest TPC and also found to be the strongest antioxidant. The 1-day fermented ECPB strongly enhanced cell viability against H2O2-induced oxidative damage in Vero cell line. This sample also exhibited good protective properties against H2O2-induced cell apoptosis as was demonstrated by a decreased quantity of sub-G1 hypodiploid cells and decreased apoptotic body formation in the flow cytometry analysis. This study demonstrated that the fermentation elevated functionally important polyphenolic contents of ECPB and resultant antioxidant activities were enhanced. Therefore, the fermentation could offer a tool to further increase the bioactive potential of ECPB.