Extraction, isolation, structural characterization, antioxidant activity and cardiomyocyte protective activity of polysaccharide from Bletilla striata leaves

BACKGROUND Although tuber polysaccharides of Bletilla striata have been extensively studied, the leaf polysaccharides, which constitute over 25% of the plant's biomass, are frequently discarded as agricultural waste. Given the well-documented bioactivities of plant polysaccharides, this represents significant untapped potential. Current cardioprotective agents exhibit limitations against doxorubicin-induced cardiotoxicity, creating demand for novel natural alternatives. This study thus aimed to isolate and characterize the primary polysaccharide from B. striata leaves and evaluate its antioxidant capacity and cardioprotective effects, thereby converting this agricultural waste into a therapeutic agent. RESULTS The purified homogeneous polysaccharide BSP-L2-1 (Mw > 500 kDa) was structurally characterized as a highly branched heteropolysaccharide featuring triple-helix conformation, with a mannose:galacturonic acid:glucose:galactose:arabinose molar ratio of 6.02:1.74:2.70:10.00:4.32. In vitro assays demonstrated potent antioxidant activity, with BSP-L2-1 achieving 72.37% inhibition of ABTS radicals at a concentration of 6 mg mL −1 . More notably, in a doxorubicin-injured H9c2(2-1) cardiomyocytes model, BSP-L2-1 exhibited significant cardioprotection by suppressing reactive oxygen species and malondialdehyde overproduction, enhancing glutathione and superoxide dismutase activity and concurrently preserving mitochondrial function. Additionally, toxicity assessments in a zebrafish model confirmed no observable adverse effects across a broad concentration range (100–900 μg mL −1 ). CONCLUSION BSP-L2-1, a novel acidic natural polysaccharide isolated from underutilized B. striata leaves, mitigated doxorubicin-induced cardiotoxicity by attenuating oxidative stress and preserving mitochondrial function. These findings support its development as a natural adjuvant to prevent doxorubicin-induced cardiotoxicity, with potential applications ranging from functional foods to pharmaceutical formulations. © 2026 Society of Chemical Industry.