Improved in vitro antioxidant properties and hepatoprotective effects of a fermented Inula britannica extract on ethanol-damaged HepG2 cells

This study aimed to improve antioxidant effect and hepatoprotective effect of Inula britannica using fermentation. Epigallocatechin gallate (EGCG) in an I. britannica extract was found to be upregulated from 2.06 to 10.28 μg/mg during fermentation (p < 0.001). After fermentation, DPPH radical-scavenging ABTS radical-scavenging, and superoxide anion-scavenging abilities increased to 92.65%, 694.25 μM Trolox/mL, and 86.38%, respectively, at 500 μg/mL (p < 0.05). Cupric-ion-reducing capacity with formation of the Cu+-neocuproine complex increased by 5.88%, 6.38%, 3.24%, and 8.55% at 62.5 to 500 μg/mL. Ferric-ion-reducing capacity of the fermented extract increased by 20%, 7.16%, 3.85%, and 5.45% at each concentration (p < 0.05). Unfermented extracts yielded cell viability of 91.42%, 90.59%, 88.38%, and 79.17%, whereas the fermented extract yielded 100.28%, 99.66%, 96.15%, and 89.90%, respectively, at each concentration in ethanol-damaged HepG2 cells (p < 0.05). Additionally, the fermented extract decreased alanine transaminase activity from 117.2 to 61.7 U/mL in the ethanol-damaged HepG2 cell line (p < 0.01). Overall, both antioxidant and hepatoprotective effect increased by fermentation in I. britannica extract. These properties are expected to lead to new antioxidant agents via production of EGCG by fermentation.