蝉虫草菌丝体胞内和胞外多糖抗肝细胞氧化损伤比较研究

蝉虫草（蝉花）作为我国传统的中药材,是一种药食两用的虫生真菌,因含有丰富的活性物质而具有广泛的医疗保健价值。本研究以自由基清除率为指标分析蝉虫草胞内和胞外多糖的化学抗氧化活性,再以H₂O₂诱导的人肝LO2细胞氧化损伤为模型,进而分析比较二者对肝细胞氧化应激损伤的改善作用。结果表明,在化学抗氧化能力比较上,蝉虫草菌丝体胞外多糖有效清除?OH自由基、ABTS自由基和DPPH自由基的EC₅₀值分别为1.06mg/mL、0.96mg/mL和0.63mg/mL,而胞内多糖的EC₅₀值分别为3.71mg/mL、2.83mg/mL和1.70mg/mL,表明蝉虫草胞外多糖的化学抗氧化能力更强;在改善细胞氧化应激损伤比较上,与模型组对比,二者均能随着浓度递增而显著地提高细胞存活率,但胞外多糖比胞内多糖更强,当多糖浓度为5mg/mL时,胞外多糖细胞存活率达到92.36%,胞内多糖只达到82.07%;在调节细胞抗氧化酶清除ROS的机制上,与模型组对比,胞外多糖分别上调SOD酶活力2.51倍和CAT酶活力2.91倍,极显著地降低了细胞ROS水平（P<0.01）来改善细胞的氧化应激损伤作用。相应地,胞内多糖只上调了1.85倍和2.33倍,显著性地清除了ROS（P<0.05）,表明蝉虫草菌丝体胞外多糖具有更显著的抗肝细胞氧化损伤作用。本研究结果显示蝉虫草菌丝体胞外和胞内多糖均具有良好的抗肝氧化损伤活性,且胞外多糖比胞内多糖活性更好,为蝉虫草菌丝体多糖在保肝产品中的开发和应用提供了科学依据。

A comparative study of intracellular and extracellular polysaccharides in mycelia of Cordyceps cicadae against oxidative damage of hepatocytes

Cordyceps cicadae, a famous Chinese traditional medicinal herb, is a kind of entomogenous fungi that contains rich bioactive substances with medical health care values. In this study, the chemical antioxidant activity and antioxidant stress damage capability of intracellular and extracellular polysaccharides from Cordyceps cicadae was investigated on the basis of radical scavenging capacity and model of hydrogen peroxide cell oxidative damage. The results showed that both intracellular and extracellular polysaccharides could scavenge ?OH free radical, ABTS free radical and DPPH free radical. The chemical antioxidant activity of extracellular polysaccharides is better than that of intracellular polysaccharides. The EC₅₀ value of scavenging ?OH free radical, ABTS free radical and DPPH free radical of intracellular polysaccharides was 3.71mg/mL, 2.83mg/mL and 1.70mg/mL respectively while that of extracellular polysaccharides was 1.06mg/mL, 0.96mg/mL and 0.63mg/mL respectively. Comparison of the capability of improving oxygenated stress damage indicated that both intracellular and extracellular polysaccharide could significantly improve LO2 cell survival rate with increase of concentration. Compared with experimental model group, the LO2 cell viability in intracellular and extracellular polysaccharide of treatment group reached 82.07% and 92.36% under treatment concentration of 5mg/mL, showing the activity of extracellular polysaccharide is obviously higher. Detection of the regulatory mechanism of scavenging ROS showed that extracellular polysaccharide increased SOD and CAT activity by 2.51 times and 2.91 times respectively, very significantly reducing the ROS level (P<0.01) and improving the oxidative stress injury of LO2 cells. Intracellular polysaccharides only increased SOD and CAT activity by 1.85 times and 2.33 times, and ROS were significantly decreased (P<0.05), indicating that improvement effect of intracellular polysaccharides on oxidative stress injury of LO2 cell was inferior. These results indicated that the polysaccharides, especially extracellular polysaccharides, extracted from mycelium of Cordyceps cicadae could scavenge free radical and protect LO2 cells avoiding oxidative damage of hydrogen peroxide.