Optimal extraction, purification and antioxidant activity of total flavonoids from endophytic fungi of Conyza blinii H. Lév

Shuheng Zhao; Xulong Wu; Xiaoyu Duan; Caixia Zhou; Zhiqiao Zhao; Hui Chen; Zizhong Tang; Yujun Wan; Yirong Xiao; Hong Chen

doi:10.7717/peerj.11223

Optimal extraction, purification and antioxidant activity of total flavonoids from endophytic fungi of Conyza blinii H. Lév

PeerJ. 2021 Apr 9:9:e11223. doi: 10.7717/peerj.11223. eCollection 2021.

Authors

Shuheng Zhao^#¹, Xulong Wu^#², Xiaoyu Duan¹, Caixia Zhou¹, Zhiqiao Zhao¹, Hui Chen¹, Zizhong Tang¹, Yujun Wan³, Yirong Xiao⁴, Hong Chen⁵

Affiliations

¹ College of Life Sciences, Sichuan Agricultural University, Ya'an, China.
² Chengdu Agricultural College, Chengdu, China.
³ Sichuan Food Fermentation Industry Research and Design Institute, Chengdu, China.
⁴ Sichuan Agricultural University Hospital, Ya'an, China.
⁵ College of Food Sciences, Sichuan Agricultural University, Ya'an, China.

^# Contributed equally.

Abstract

Background: Flavonoids are widely used in the market because of their antibacterial, antiviral, and antioxidant activities. But the production speed of flavonoids is limited by the growth of plants. CBL9 (Chaetomium cruentum) is a flavonoid-producing endophytic fungi from Conyza blinii H. Lév, which has potential to produce flavonoids.

Methods: In this study, we isolated total flavonoids from endophytic fungus CBL9 of Conyza blinii H. Lév using macroporous resin D101. The process was optimized by response surface and the best extraction process was obtained. The antioxidant activities of total flavonoids were analyzed in vitro.

Results: It was found that the best parameters were 25 °C pH 2.80, 1.85 h, and the adsorption ratio reached (64.14 ± 0.04)%. A total of 60% ethanol was the best elution solvent. The elution ratio of total flavonoid reached to (81.54 ± 0.03)%, and the purity was 7.13%, which was increased by 14.55 times compared with the original fermentation broth. Moreover its purity could rise to 13.69% after precipitated by ethanol, which is very close to 14.10% prepared by ethyl acetate extraction. In the antioxidant research, the clearance ratio of L9F-M on DPPH, ABTS, •OH, •O^2-, (96.44 ± 0.04)% and (75.33 ± 0.03)%, (73.79 ± 0.02)%, (31.14 ± 0.01)% at maximum mass concentration, was higher than L9F.

Conclusion: The result indicated using macroporous resin in the extraction of total flavonoid from endophytic fungus is better than organic solvents with higher extraction ratio, safety and lower cost. In vitro testing indicated that the flavonoid extracted by macroporous resin have good antioxidant activity, providing more evidence for the production of flavonoid by biological fermentation method.

Keywords: Chaetomium cruentum; Flavonoid; Macroporous resin; Response surface.

Grants and funding

This work was supported by the Application Fundamentals (Key) R&D Project of Sichuan Provincial Science and Technology Department (Grant No. 2019YJ0549), Seedling Project Cultivation Project (Grant No. 2019058) and the Key R&D Project of Sichuan Provincial Department of Science and Technology (Grant No. 2019YFG0154). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.