一株红茄苳内生烟曲霉菌的分离鉴定及其发酵产物抗氧化活性

Isolation, identification and antioxidant activity Aspergillus fumigatus HQD24 endophytic in Rhizophora mucronata

摘要:

【目的】红树林内生真菌生长于特殊的生境，有些菌株能分泌出结构新颖和具有生物活性的物质。从红树林植物红茄苳(Rhizophora mucronata)中分离获得一株内生真菌HQD24，对其进行生物学鉴定和抗氧化活性评价。【方法】综合运用形态结构及ITS rDNA序列分析，HQD24被鉴定为曲霉属(Aspergillus)的烟曲霉(Aspergillus fumigatus)。采用抗氧化多活性模型，2-2′二苯基-1-三硝基苯肼(DPPH)自由基测定法、2′-联氨-双-3-乙基苯并噻唑啉-6-磺酸(ABTS)自由基测定法、超氧自由基测定法、还原Fe3+能力、螯合Fe2+能力对HQD24麦麸发酵提取物的石油醚萃取物、二氯甲烷萃取物、乙酸乙酯萃取物和正丁醇萃取物进行抗氧化活性评价。【结果】经抗氧化活性实验发现不同有机溶剂萃取成分都具有清除DPPH自由基、ABTS自由基、超氧自由基和还原Fe3+、螯合Fe2+的能力，尤其是清除ABTS自由基和超氧自由基，抗氧化活性的能力都随着浓度的增高而增强。当不同有机溶剂萃取粗提物浓度为1.5 g/L时，二氯甲烷萃取物清除ABTS自由基率为71.92%，正丁醇萃取物清除超氧自由基率为62.36%，综合评价，HQD24的发酵产物中具有抗氧化活性的物质主要分布于二氯甲烷萃取粗提物和正丁醇萃取粗提物，其次分布于乙酸乙酯萃取粗提物，石油醚萃取粗提物中抗氧化活性物质含量最少。【结论】研究结果预示红树林内生烟曲霉菌是产生抗氧化活性物质的重要资源，HQD24菌株可以作为进一步实验研究的对象。

Abstract:

[Objective] Some of mangrove endophytic fungi inhabitated in special ecological which were enabled to secrete novel and biologically active compounds. In this study, an endophytic fungus HQD24 with antioxident activity was isolated from Rhizophora mucronata in Dong Zhai Gang-Mangrove Garden on Hainan Island and its antioxidant activity of crude extracts were evaluated. [Methods] Strain HQD24 was identified as Aspergillus fumigatus based on the morphological characteristic and ITS rDNA sequence analysis. Fermentation substrate were extracted with petroleum ether, chloroform, ethyl acetate and n-butanol successively. The antioxidant activity of were evaluated using radical scavenging activity on DPPH (2,2′-diphenyl-1-picrylhydrazyl) and ABTS (2,2′-azino-bis (3-ethylbenzothiazoline-6-sulphonicacid)), reducing Fe3+ capacity, chelating Fe2+ ability and superoxide radical-scavenging activity. [Results] The crude extract and all fractions possessed antioxidant and radical-scavenging activities in different assays. ABTS and superoxide radical-scavenging abilities were enhanced with the increase of the extract concentration. Chloroform fraction exhibited higher scavenging ability on ABTS radical reaches 71.92%, n-butanol fractions was found to be the most effective in superoxide radical scavenging reaches 62.36% with concentration of 1.5 g/L. The results indicating most of the antioxidant compounds of HQD24 are distributed in the chloroform and n-butanol fractions, followed by the ethyl acetate, and petroleum ether fraction. [Conclusion] Strain HQD24 was identified as Aspergillus fumigatus, which to be a promising resource with antioxidant activity for further investigation