民族药马利筋内生真菌生物活性研究

Biological activities of endophytic fungi from Asclepias curassavica

关键词:  马利筋, 内生真菌, 抗肿瘤, 抗炎, α-葡萄糖苷酶抑制剂, DPPH自由基, ITS

Key words:  Asclepias curassavica, endophytic fungus, anti-tumor, anti-inflammatory, α-glucosidase inhibitor, DPPH free radical, ITS

摘要:

药用植物内生真菌能产生与宿主相同或相似的活性物质,民族药马利筋生物活性广泛。为获得马利筋活性内生真菌资源,该研究基于“民族药-内生真菌-活性成分”的思路,考察了168株马利筋内生真菌代谢产物的生物活性,并分别采用SRB法、Griess法、PNPG法和DPPH法对内生真菌发酵液乙酸乙酯提取物进行抗肿瘤、抗炎、α-葡萄糖苷酶抑制和抗氧化等生物活性测定,对活性菌株进行ITS菌种鉴定。结果表明:(1)所筛选的168株内生真菌中有22株表现出不同程度的生物活性。其中,9株内生真菌具有显著抗肿瘤活性,其IC₅₀值在0.1 ～ 40 μg·mL^-1之间; 菌株MJF-53在2.5 μg·mL^-1时对LPS诱导的Raw264.7释放的NO和IL-1β均具有明显的抑制作用; 7株内生真菌表现出不同程度的α-葡萄糖苷酶抑制活性,其IC₅₀值在1.0 ～ 4.0 mg·mL^-1之间,其中MYF-16和MYF-55对α-葡萄糖苷酶抑制活性接近阿卡波糖; 19株内生真菌具有不同程度的DPPH自由基清除活性,其中菌株MYF-9、MYF-19和MJF-84表现出中等强度的抗氧化活性,IC₅₀值分别为13.562、17.776、12.395 μg·mL^-1。(2)ITS菌株鉴定发现,22株活性菌株分属于链格孢属(Alternaria sp.)、刺盘孢属(Colletotrichum sp.)、镰刀菌属(Fusarium sp.)、间座壳属(Diaporthe sp.)、踝节菌属(Talaromyces sp.)和新壳梭孢属(Neofusicoccum sp.)等不同属。研究结果认为,马利筋内生真菌的生物活性具有多样性,可为从马利筋内生真菌中挖掘潜在新型天然抗肿瘤、抗炎、降糖和抗氧化活性化合物奠定基础。

Abstract:

Endophytic fungi in medicinal plants have the capacity to produce bioactive compounds whose features have great identity or similarity with the phytohosts. Since Asclepias curassavica has been known to possess a broad range of biological activities, we sought to obtain the active endophytic fungi from this plant. We performed the study followed the idea of “ethnic drug-endophytic fungi-active ingredients”, and thereafter we examined the bioactivities of fungal metabolites from 168 strains of endophytic fungi isolated from A. curassavica. To evaluate the biological activities of anti-tumor, anti-inflammatory, anti-α-glucosidase and anti-oxidant in these fungi, the ethyl acetate extracts from fermentation broth of endophytic fungi were first determined using the methods of SRB, Griess, PNPG and DPPH, respectively. Furthermore, we identified the bioactive fungal strains with conserved ITS sequencing. The results were as follows:(1)A total of 22 in 168 isolated strains had variable biological activities. Nine strains had obvious anti-tumor effect with the IC₅₀ values of 0.1-40 μg·mL^-1. Further, the strain MJF-53 displayed prominent inhibitory effects on the release of both NO and IL-1β in Raw264.7 cell line by LPS- induction under the concentration of 2.5 μg·mL^-1. There were seven strains showing α-glucosidase inhibitory activity with the IC₅₀ values ranging from 1.0 to 4.0 mg·mL^-1, especially, the inhibitory activities of MYF-16 and MYF-55 were close to acarbose; 19 endophytic fungi had different degrees of DPPH free radical scavenging activities, among which MYF-9, MYF-19 and MJF-84 showed moderate anti-oxidant activities with IC₅₀ values of 13.562, 17.776 and 12.395 μg·mL^-1 respectively.(2)The ITS identification showed that the 22 active strains were mainly distribute in six genera: Alternaria sp., Colletotrichum sp., Fusarium sp., Diaporthe sp., Talaromyces sp. and Neofusicoccum sp. This study indicates that the bioactivities of the endophytic fungi from A. curassavica are diverse, which lays a foundation for exploring new potential natural anti-tumor, anti-inflammatory, hypoglycemic and anti-oxidant compounds from the endophytic fungi of A. curassavica.