Short-Term Pretreatment of Naringin Isolated from Citrus Wilsonii Tanaka Attenuates Rat Myocardial Ischemia/Reperfusion Injury

Abstract Pretreatment or treatment with anti-apoptotic, anti-inflammatory, or anti-oxidative approaches could be critical for reducing the occurrence of myocardial I/R injury. Naringin, a natural flavonoid, plays important roles in inflammation-related diseases. Immature dry fruits of Citrus wilsonii Tanaka (Xiang Yuan) are rich in naringin that can be used as traditional Chinese medicine to treat inflammation-related symptoms. However, its roles in cardioprotective role remain unclear. This study aimed to isolate naringin from Citrus wilsonii Tanaka fruit and test their cardioprotective effect. The dry fruits of Citrus wilsonii Tanaka were extracted with boiling water and then supernatants were freeze-dried to yiled aqueous extract (ZQAE). The extract was chemoprofiled using UPLC-MS/MS to stand for major constituents, then subjected to different chromatographic separation steps and naringin was isolated in a high yield. The cardioprotective effect of the aqueous extract of ZQAE and naringin were investigated in a myocardial I/R rat model and to elucidate the mechanism underlying its cardioprotective effect. Naringin was successfully isolated from ZQAE powder by recrystallization in a very high yield. Our results indicated that 5-day ZQAE and naringin pretreatment both promoted histopathological changes and reduced myocardial enzymes induced by I/R. Moreover, the 50mg/kg and 100mg/kg ZQAE doses pretreatment presented a striking decreased the infarct size as well as myocardial enzyme levels but also inhibited myocardial apoptosis, the inflammatory response and oxidative stress. The cardioprotective effect of 5mg/kg dose of naringin pretreatment is comparable with that of 5mg/kg drug ditiazem pretreatment. Additionally, Naringin pretreatment exhibited striking decreases in the apoptosis index and downregulation of cleaved-Caspase3 protein expression. Meanwhile, naringin downregulated HMGB1 expression and upregulated SIRT1 expression in the myocardium. These findings suggest that short-term pretreatment with ZQAE and naringin both protect against myocardial I/R injury by suppressing myocardial apoptosis, the inflammatory response and oxidative stress. The cardioprotective effect of naringin involves SIRT1 activation and may interact with HMGB1 and inhibit the release of HMGB1.