白及内生真菌的分离鉴定及其胞外多糖的抗氧化活性分析

目的:缓解白及药用资源压力,分离鉴定白及内生真菌并进行内生真菌胞外多糖活性强弱研究。方法:分离鉴定白及内生真菌,进行液体发酵培养获得胞外多糖,通过建立铁氰化钾法,2,2-联苯基-1-苦基肼基(DPPH)法,水杨酸法,2-联氨-双-3-乙基苯并噻唑啉-6-磺酸(ABTS)法4种体外模型研究白及内生真菌胞外多糖的抗氧化活性。结果:从白及新鲜根中分离得到10株内生真菌,鉴定合并菌株后得到6株不同的菌株,其中10号菌株胞外多糖(0.1 g·L-1)总还原力最强,其维生素C(VC)当量高达12.01 mg·L-1,其次为6号菌株;清除DPPH自由基活性最强的为1号和6号菌株为16.6%;6号菌株清除羟基自由基活性最强为21.6%,最弱的为10号菌株仅为11.0%;测定其清除ABTS自由基活性时则发现,10号菌株活性最强为13.6%,其次为6号菌株,最弱的为5号仅为1.8%。结论:白及内生真菌胞外多糖具有一定的抗氧化活性,其中6号菌株胞外多糖总还原力,清除DPPH自由基活性,清除羟基自由基活性、清除ABTS自由基均较好,可以加以开发和利用。

Isolation and Identification of Endophytic Fungi of Bletillae Rhizoma and Investigation of Antioxidative Activity of Its Exopolysaccharides

Objective: To isolate and identify Bletillae Rhizoma fungi and study on the exopolysaccharides activity of endophytic fungi, in order to alleviate the pressure of Bletillae Rhizoma medicinal resources. Method: Bletillae Rhizoma endophytic fungi were isolated and identified, and then exopolysaccharides were obtained through liquid fermentation. The antioxidant activity of exopolysaccharide in Bletillae Rhizoma roots endophytic fungi was studied by establishing 4 kinds of in vitro models, including iron potassium cyanide, 2, 2-diphenyl-1-picrylhydrazyl (DPPH), salicylic acid and 2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) methods. Result: The 10 endophytic fungi were isolated from Bletillae Rhizoma fresh roots, and 6 strains were obtained after identification and combination. The exopolysaccharides of No.10 strain (0.1 g L^-1) had the strongest total reducing power, with VC equivalent up to 12.01 mg·L^-1, followed by No. 6 strain. No. 1 and No. 6 strains had the strongest DPPH free radical scavenging activities (16.6%). Strain 6 had the strongest hydroxyl radical scavenging activities (21.6%) and No.10 strain had the weakest activity (11.0%) on scavenging hydroxyl radical. In the detection of ABTS free radical scavenging activity, it was found that No. 10 strain had the strongest activity (13.6%), followed by No. 6 strain, and the weakest was only 1.8% for No. 5 strain. Conclusion: The exopolysaccharides of Bletillae Rhizoma endophytic fungi has certain antioxidant activity, and the exopolysaccharides of No. 6 strain has better total reducing power, higher scavenging activities of DPPH free radicals, hydroxyl radicals, and ABTS free radicals, so it can be further developed and utilized.