Antioxidant activity of sea cucumber (Stichopus japonicus) gut hydrolysates-ribose Maillard reaction products derived from organic reagent extraction

The purpose of the present study was to explore the antioxidant activity of organic extracts from Maillard reaction products (MRPs) of sea cucumber ( Stichopus japonicus ) gut hydrolysates (SCGHs). The SCGHs were obtained after treatment with neutrase, and they were then reacted with ribose at a mass ratio of 1:2, pH 8.0, and 95 °C for up to 12 h. The MRPs were extracted by methanol and ethanol. The methanol extracts of the MRPs had a higher UV absorbance, browning intensity, and fluorescence intensity than the crude MRPs. The scavenging capacities of methanol and ethanol extracts from MRPs in both 2′,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) assays increased significantly ( p  < 0.05). The methanol extracts were better than the ethanol extracts showing the reduced IC 50 levels for ABTS and DPPH by 50% and 50%, respectively. The inhibitory activity for peroxidation of linoleic acid of MRPs was also enhanced in the methanol extracts of MRPs, but this was reduced in ethanol extracts. Moreover, HepG2 cell viability after exposure to the methanol extracts of MRPs was increased to 59.30 ± 0.43% compared with the SCGHs and MRPs, which was 3.97 times that of the H 2 O 2 -treated group. These results suggest that methanol extraction can improve the antioxidant activity of SCGHs-ribose MRPs and that the corresponding extracts can be potentially used as food antioxidants.