This growing interest in the cultivation of Japanese quince Chaenomeles japonica L. results from the potentially beneficial properties of its fruit. Fresh fruits are very firm and too acidic to eat raw, but their bioactive components, distinctive aroma, and high amount of dietary fiber make the fruits well suited for industrial processing. However, not all the properties of the fruit have been investigated. For example, there are no comprehensive reports about the mineral content or potentially harmful effects on liver metabolism. Hence, the purpose of our study was to examine fresh Japanese quince fruit in terms of (1) ascorbic acid, oxalate, fiber, macro- and micronutrients, dry matter, extract, total acidity, antioxidant activity, and phenolic compound levels; and (2) the effect of its extract on in vitro hepatocyte metabolism, measured by the concentration of lipid peroxides (LPO) and reactive oxygen species (ROS) and the severity of apoptosis and necrosis. The fruit of C. japonica had high levels of macro- and microelements, ascorbic acid, phenolic compounds, fiber, and low oxalate levels. Our analysis of macro- and microelements showed that the average content of Fe was 0.516 mg/g, Cu 0.146 mg/g, Zn 0.546 mg/g, Mg 16.729 mg/g, and Ca 22.920 mg/g of fresh fruit. A characteristic feature of the fresh fruit of C. japonica is a high level of polyphenols, which-combined with a high content of vitamin C-affect their high antioxidant potential. In the tested hepatocyte cultures incubated with extract of the Japanese quince, we observed a significant decrease in the concentration of lipid peroxides compared to the control. There were also no signs of increased formation of ROS in the mitochondria of hepatocytes incubated with the extract of quince. Malondialdehyde was strongly negatively correlated with the concentration of Japanese quince extract, which indicates the hepatoprotective properties of Japanese quince. In addition, our analysis of confocal microscopy images showed that the hepatocytes incubated with the extract of Japanese quince at any concentration did not show any signs of apoptosis or necrosis. The aqueous extract of quince fruit has antioxidative and antiapoptotic hepatocytes, thus exerting a hepatoprotective effect.
Keywords: Apoptosis; Chaenomeles japonica L.; Hepatocyte metabolism; Japanese quince extract; Lipid peroxide; Reactive oxygen species (ROS).