(Provided by Wan-Ju Yeh Assistant Professor and her team from the Undergraduate Program of Nutrition Science)

Alcoholic liver disease (ALD) has become a health problem as alcohol consumption has increased annually both in Taiwan and around the world. Hepatic lipid accumulation, oxidative stress, and inflammation are important factors in the progression of ALD. Red pitaya (Hylocereus polyrhizus) peel is rich in polyphenols and betanins, which possess antioxidative and anti-inflammatory properties. Therefore, this study aimed to investigate the effects of red pitaya peel extract (PPE) on ALD, and explore the associated mechanisms. Laboratory mice were administered an ethanol liquid diet, which induced ALD, and PPE treatment was shown to reduce hepatic fat accumulation, oxidative stress, and inflammation. Thus, PPE may help prevent the progression of ALD.

According to a report by the World Health Organization, alcohol consumption is related to the risks of many diseases and public health problems, one of which is alcoholic liver disease (ALD), which can progress to fibrosis and even liver cancer. Alcohol-induced lipid metabolism impairment, increased oxidative stress, and proinflammatory responses play important roles in the pathogenesis of ALD. Proper therapeutic management at an early stage of disease may therefore be helpful in retarding disease progression or in ameliorating liver injury. Red pitaya (Hylocereus polyrhizus) is one of the most popular fruits in Taiwan, the peel of which represents almost one-third of the total fruit weight and is rich in phenolic compounds and betaine. PPE was shown to have potential for antioxidative activities, and betaine was reported to moderate lipid metabolism. Therefore, this study employed fresh red pitaya harvested locally in Taiwan, the peel of which was cut into small pieces, dried, placed in 50% ethanol and stirred at room temperature for 30 minutes. The filtrate was then concentrated and freeze-dried, which produced red pitaya peel extract (PPE).

The experiment was carried out by feeding laboratory mice an ethanol liquid diet, which induced ALD. PPE supplementation was included in the diet to investigate the effects of PPE on ALD. The results showed that the mice that were fed the ethanol liquid diet had significantly higher serum aspartate transaminase (AST), ALT (alanine transaminase), and γ-GT (gamma glutamyl transpeptidase), and their livers were shown to have significantly higher hepatic lipid accumulation, oxidative stress, and inflammation, indicating a successful establishment of the ALD model. PPE was included in the intervention group’s ethanol liquid diet, and it was shown that PPE had no effect on the animals’ body weight and food intake, but showed significant improvements in AST, lipid accumulation, oxidative stress, and inflammation. As shown in Figure 1, these findings suggest that PPE may prevent the progression of ALD and can therefore be used in dietary planning or functional food development.

Figure 1. Possible mechanisms of the hepatoprotective effects of PPE on mice with alcoholic liver disease.

原文出處：https://www.mdpi.com/2072-6643/12/12/3884