Structural characterization and cardioprotective activity of a novel polysaccharide from Fructus aurantii

Fructus aurantii is a well-known plant commonly used to treat cardiovascular diseases in China. The Fructus aurantii polysaccharide CALB-3 has been shown to exhibit antioxidant activity in vitro and in vivo. We aimed to further characterize the structure of CALB-3 and investigate its protective effects against hypoxia/reoxygenation-mediated myocardial injury in vitro. To this end, here, the effect of CALB-3 was tested against hypoxia/reoxygenation-induced oxidative stress, antioxidant enzyme and reactive oxygen species levels, and apoptosis-related protein expression in H9c2 cells. Our results showed that CALB-3 had a molecular weight greater than 805.0 kDa and a → 3)-α-Galp-(1→, →3, 4)-α-Galp-(1→, and →3)-β-Arap-(1 → backbone. Pretreatment with CALB-3 elevated survival rate, improved endogenous antioxidant enzyme activity, inhibited reactive oxygen species production, reduced mitochondrial membrane potential, downregulated the pro-apoptosis protein Bax, and upregulated the anti-apoptosis protein Bcl-2. The protective effects were correlated with Akt signaling, suggesting that CALB-3 exerts its cardioprotective effects via Akt signaling.