Xyloglucan intake attenuates myocardial injury by inhibiting apoptosis and improving energy metabolism in a rat model of myocardial infarction

The development of coronary heart disease can be divided into preocclusion and postocclusion steps. We previously showed that cell wall polysaccharides consisting of a high content of arabinose and/or xylose, such as apple pectin, protected against myocardial injury by inhibiting postocclusion steps. We hypothesized that xyloglucan, another apple cell wall polysaccharide that consists of a high content of xylose, might also show myocardial protection. To test the hypothesis, rats were supplemented with either tamarind xyloglucan (TXG) (1, 10, and 100 mg/kg per day) or cotton cellulose (CCL) (100 mg/kg per day) for 3 days. Then, rats underwent 30 minutes of ischemia followed by 3 hours of reperfusion. Supplementation with TXG at a dosage greater than 10 mg/kg per day significantly reduced the infarct size (IS), whereas supplementation with CCL at 100 mg/kg per day did not reduce IS. TXG supplementation up-regulated the expression of myoglobin and fatty acid-binding protein, both of which are known to be involved in apoptosis and ATP generation. Indeed, TXG supplementation inhibited apoptosis through decrease in p38 and JNK phosphorylation, increase in Bcl-2/Bax ratio, inhibition in the conversion of procaspase-3 to cleaved caspase-3, and decrease in the generation of DNA nicks. From these results, we demonstrated that xyloglucan in apple can protect against myocardial injury by inhibiting apoptosis and improving energy metabolism. Therefore, apple xyloglucan and pectin contribute to the known beneficial effects of apple in reducing the risk of coronary heart disease by blocking postocclusion steps through apoptosis inhibition. In addition, this study demonstrates the feasibility of developing TXG as a cardioprotectant.