Larch Arabinogalactan Attenuates Myocardial Injury by Inhibiting Apoptotic Cascades in a Rat Model of Ischemia-Reperfusion.

We reported previously that supplementation with apple pectin, a dietary fiber, reduced myocardial injury in a rat model of ischemia-reperfusion. In this study, we further investigated an arabinogalactan, one of the constituent polysaccharides of pectin, to determine which domains comprising pectin were responsible for the protection. In a rat model of 30-min ischemia followed by 3-h reperfusion, supplementation with larch arabinogalactan (LAG) over 50 mg/kg/day significantly reduced infarct size. Reverse transcription polymerase chain reaction (RT-PCR), immunohistochemistry, and immunoblot analyses showed that intake of LAG blocked the steps involved in apoptotic cascades through downregulation of gelsolin gene expression at the protein (Gelsolin) level, inhibition of p38 phosphorylation in mitogen-activated protein kinase (MAPK) pathways, decreased bax/bcl-2 ratio at the protein (Bax/Bcl-2) level, which was correlated with the ratio at the mRNA level, inhibition of the conversion of Procaspase protein to Caspase-3 protein, and consequently a decrease in apoptotic cells. In addition, the intake of LAG reduced the hif1-α gene expression at the protein (HIF1-α) level. These findings suggest that arabinogalactan is an active component of pectin for reducing myocardial injury by inhibiting apoptosis in postocclusion steps, possibly indicating that arabinogalactan can be developed as a cardioprotectant to prevent myocardial injury.