Antioxidant and hepatoprotective effects against acute CCl4 -induced liver damage in mice from red-fleshed apple flesh flavonoid extract.

Apple (Malus domestica Borkh.) is an important fruit tree species worldwide. Apple fruits are favored by consumers because of their antioxidative, anti-inflammatory, and antitumor effects as well as their protective effects against cardiovascular diseases and other health benefits. There is considerable interest in red-fleshed apple fruits among breeders because of their high flavonoid and anthocyanin contents. However, the flavonoids extracted from red-fleshed apple fruits must still be functionally characterized, especially regarding their protective effects against certain pathologies. In this study, the flavonoid components and contents in the extracts prepared from red-fleshed apple cultivar "Meihong" were determined. Additionally, the in vitro antioxidant activities and protective effects of the extracts against CCl4 -induced acute liver injury were investigated. The red-fleshed apple flesh flavonoid extract (RAFF) exhibited strong in vitro antioxidant activities. Compared with the model control mice treated with CCl4 , the mice pretreated with high (800 mg/kg·bw), middle (400 mg/kg·bw), and low (200 mg/kg·bw) RAFF doses had significantly lower CCl4 -induced serum aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase activities. Moreover, the RAFF pretreatment also significantly decreased the liver malondialdehyde activity and prevented the CCl4 -induced decrease in liver superoxide dismutase, glutathione peroxidase, catalase, and reduced glutathione levels. Furthermore, a histopathological examination revealed that RAFF inhibited the inflammatory cell infiltration and cell boundary loss caused by CCl4 in the liver. Thus, RAFF is a natural antioxidant with significant antioxidative activities and liver protective effects. The results of this study may be relevant for enhancing the application of the red-fleshed apple fruit extract as a food additive. PRACTICAL APPLICATION: We took the self-selected red-fleshed apple cultivar "Meihong" as the unique research material, and the active ingredients of its flavonoid extract, in vitro antioxidant activity and hepatoprotective effect were analyzed. It is of great significance to promote the development of the red-fleshed apple industry, and also provides an important reference for the development of natural antioxidants.