Protective effect of polyphenols from /Glycyrrhiza glabra/ against oxidative stress in Caco-2 cells

In the present article, we have investigated the antioxidant properties of methanolic liquorice polyphenol extracts (LPEs). Polyphenol extraction was performed with 60% and 100% methanol. Analysis of LPEs by thin-layer chromatography revealed that a higher amount of polyphenols was recovered by extraction with 60% methanol. Antioxidant activity measurement of the reducing power, scavenging effect on 2,22-diphenyl-1-picrylhydrazyl free radical, and hydrogen peroxide scavenging capability have been taken as the parameters for assessment of antioxidant potential of LPEs. Results have been compared with both natural and synthetic antioxidants. All experimental data have indicated that LPEs possess strong antioxidant power proportional to their o-diphenolic and total polyphenolic content, independently from the assay used. Therefore, the LPEs antioxidant property was examined against the cytotoxic effects of reactive oxygen species in human colon carcinoma cells. Pretreatment of Caco-2 cells with liquorice polyphenolic extracts provided a remarkable protection against oxidative damage induced by H2O2. The highest oxidative stress protection (72% of cell vitality) was measured in cells pretreated with 0.54 mM polyphenols. This effect seems to be associated to the antioxidant activity of liquorice polyphenolic compounds. Our data suggest that polyphenols from Glycyrrhiza glabra could exert a beneficial action in the prevention of intestinal pathologies related to production of reactive oxygen species.