The anti-oxidative capacity of fermented lemon peel and its inhibitory effects on Lipopolysaccharide (LPS)-induced RAW 264.7 cell inflammatory response and cell apoptosis

Abstract

Chronic inflammation plays a key role in the development and progression of several chronic diseases. Inhibiting the inflammatory cascade, thereby minimising the damage caused by the inflammatory mediators, can be one of the strategies in chronic disease management. In addition, inflammation is closely related to apoptosis, and inflammation can cause apoptosis. Lemon peel has been reported to have antioxidant and anti-inflammatory biological activities. This study aimed to investigate the antioxidant activity of fermented lemon peel (FLP) by Lactobacillus plantarum PNU and the effect of its extract (FLPE) on LPS-induced inflammatory response in RAW 264.7 cells. The results show that FLP has better antioxidant activity than unfermented lemon peel (UFLP). Compared with UFLP extract, FLPE more effectively inhibited the release of NO and pro-inflammatory cytokines (IL-1β, IL-6, TNF-α and IFN-γ) and down-regulated pro-inflammatory genes (IL-1β, IL-6, NF-κB p65, COX-2, IFN-γ, iNOS, IL-5), and pro-apoptotic genes (caspase-3, caspase-9, p53, p21 and Bax), meanwhile, promoted the release of anti-inflammatory cytokine (IL-10) and up-regulated anti-inflammatory genes(IL-10 and IL-4), and anti-apoptotic gene (Bcl2) in LPS-induced RAW 264.7 cells. Therefore, this study elucidates the anti-inflammatory activity mechanism of fermented lemon peel by studying the balance of inflammatory response and the inhibition of apoptosis. It provides an important reference for the future research and treatment of chronic inflammation and related diseases, as well as the development of fermented foods with anti-inflammatory effects.

Keywords:
lemon peel; fermentation; RAW 264.7 cell; inflammation; apoptosis