Optimization of Fermentation Process of Pomegranate Peel and and the Biological Activities of Fermentation Broth: Antioxidant Activity and Protective Effect Against HO-induced Oxidative Damage in HaCaT Cells.

In this study, the lactobacillus fermentation process of pomegranate ( L.) peel and (Turcz.) Baill (PP&SC) was optimized by using the response surface method (RSM) coupled with a Box-Behnken design. The optimum fermentation condition with the maximal yield of ellagic acid (99.49 ± 0.47 mg/g) was as follows: 1:1 () ratio of pomegranate peel to , 1% () of strains with a 1:1 () ratio of to , a 37 °C fermentation temperature, 33 h of fermentation time, 1:20 (g:mL) of a solid-liquid ratio and 3 g/100 mL of a glucose dosage. Under these conditions, the achieved fermentation broth (FB) showed stronger free radical scavenging abilities than the water extract (WE) against the ABTS, DPPH, OH and O radicals. The cytotoxicity and the protective effect of FB on the intracellular ROS level in HaCaT cells were further detected by the Cell Counting Kit-8 (CCK-8) assay. The results showed that FB had no significant cytotoxicity toward HaCaT cells when its content was no more than 8 mg/mL. The FB with a concentration of 8 mg/mL had a good protective effect against oxidative damage, which can effectively reduce the ROS level to 125.94% ± 13.46% ( < 0.001) compared with 294.49% ± 11.54% of the control group in HO-damaged HaCaT cells. The outstanding antioxidant ability and protective effect against HO-induced oxidative damage in HaCaT cells promote the potential for the FB of PP&SC as a functional raw material of cosmetics.