Improving Antioxidant Activity of Ophioglossum thermale Kom. by Fermentation with Talaromyces purpurogenus M18-11

Ophioglossum thermale Kom. was fermented with several fungi. The total phenolic and flavonoid contents (TPCs and TFCs) and antioxidant activities of fermented and non-fermented O. thermale (FOT and NFOT) were investigated. The results showed that Talaromyces purpurogenus M18-11 fermented O. thermale possessed significantly improved TPC and TFC and exhibited significantly stronger 1,1-diphenyl-2-picrylhydrazyl (DPPH) (half maximal inhibitory concentration (IC50) = 75.7 ± 2.1 μg mL-1) and 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) (IC50 = 20.52 ± 1.68 μg mL-1) free-radical scavenging activities, ferric reducing antioxidant power (0.585 ± 0.045 mmol g-1), and reducing power (half maximal effective concentration (EC50) = 30.52 ± 1.91 μg mL-1) than original material. The determination of the contents of representative flavonoids and their glucosides revealed that the improvements are attributed to the hydrolysis of homoisoflavonoid and flavonoid glucosides, glycometabolism, as well as fungal metabolites. This paper is the first to report the fermentation of O. thermale with pure strains and T. purpurogenus is an effective strain to process O. thermale for improving the antioxidant activity.

采用多株真菌对热地瓶尔小草（Ophioglossum thermale Kom.）进行发酵处理。本研究考察了发酵热地瓶尔小草（FOT）与未发酵热地瓶尔小草（NFOT）的总酚含量（total phenolic contents，简称TPCs）、总黄酮含量（total flavonoid contents，简称TFCs）及抗氧化活性。实验结果显示，经紫色篮状菌（Talaromyces purpurogenus）M18-11菌株发酵后的热地瓶尔小草，其总酚与总黄酮含量显著提升，且相较于原始原料，其1,1-二苯基-2-苦基肼基（1,1-diphenyl-2-picrylhydrazyl，缩写DPPH）自由基清除活性（半最大抑制浓度（half maximal inhibitory concentration，简称IC50）=75.7±2.1 μg·mL⁻¹）、2,2'-联氮-双(3-乙基苯并噻唑啉-6-磺酸)二铵盐（2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt，缩写ABTS）自由基清除活性（IC50=20.52±1.68 μg·mL⁻¹）、铁还原抗氧化能力（ferric reducing antioxidant power）为0.585±0.045 mmol·g⁻¹，以及还原力的半最大有效浓度（half maximal effective concentration，简称EC50=30.52±1.91 μg·mL⁻¹）均显著增强。通过对代表性黄酮类化合物及其糖苷类衍生物的含量测定，发现活性提升可归因于高异黄酮类与黄酮类糖苷的水解、糖代谢过程以及真菌代谢产物的协同作用。本研究首次报道了采用纯菌株发酵热地瓶尔小草的相关研究，且紫色篮状菌M18-11是用于加工热地瓶尔小草以提升其抗氧化活性的高效菌株。