Cardioprotective and antioxidant activities of a polysaccharide from the root bark of Aralia elata (Miq.) Seem

A water-soluble polysaccharide (AEP-w1) was isolated from the root bark of Aralia elata and its molecular weight was about 4.5 × 10⁴ Da. Monosaccharide component analysis indicated that AEP-w1 appeared to be arabinogalactan, consisting of arabinose, galactose and trace glucose with molar ratios of 6.3:3.5:0.2. The antioxidant and cardioprotective potential of AEP-w1 were evaluated in vitro for the first time. AEP-w1 showed potent superoxide and hydroxyl radical scavenging activities and reducing power in vitro. Treatment with H₂O₂ resulted in the death of H9c2 cells, whereas pretreatment with 50-400 μg/ml AEP-w1 for 24 h prior to H₂O ₂ exposure significantly increased cell viability. Furthermore, AEP-w1 evidently suppressed cardiomyocyte apoptosis, the mitochondrial membrane potential change and cytochrome c release in H₂O₂-treated H9c2 cells. In addition, intracellular reduced glutathione (GSH) reduction caused by H₂O₂ in H9c2 cells was also restored by AEP-w1 pretreatment. Taken together, these date provided the first evidence that the cardioprotective effects of AEP-w1 in H9c2 cells were at least in part associated with its antioxidant activity and inhibition effect on mitochondrial dysfunction.