Isochromenes from the Nicotiana tabacum-derived endophytic fungus Aspergillus versicolor and their anti-tobacco mosaic virus activities

Abstract

Three new isochromenes, (5-methoxy-7-prenyl-1H-isochromen-3-yl)methanol (1), 3-(3-(hydroxymethyl)-5-methoxy-1H-isochromen-7-yl)propan-1-ol (2), and (5-methoxy-7-methyl-1H-isochromen-3-yl)methanol (3), along with three known analogues (4–6) were isolated from the fermentation products of a Nicotiana tabacum-derived endophytic fungus Aspergillus versicolor. Their structures were elucidated by spectroscopic methods, including extensive 1 D and 2 D NMR techniques. Compounds 1–3 and 6 were evaluated for their anti-tobacco mosaic virus (anti-TMV) activities. The results showed that compound 2 exhibited high anti-TMV activity with inhibition rate of 46.4%, and this rate is higher than that of positive control. Compounds 1, 3, and 6 also showed potential anti-TMV activity with inhibition rates of 28.6, 30.5, and 26.2%, respectively. The IC₅₀ of compounds 1–3 and 6 were also tested, and showed IC₅₀ values of 49.3, 22.4, 42.2, and 54.1 µM, respectively.

Graphical Abstract

Keywords:

• Isochromenes
• endophytic fungus
• Aspergillus versicolor
• anti-TMV activities

Authors contributions

FXY conducted most of the practical work. JMD and FXY elucidated the structures, JW did IR-spectroscopy, HYL and QLM sequenced the fungus, JDZ planned and performed the bioassays, XML, WGW, MZ, YKL, FXY and QFH wrote the manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This project was supported financially by the National Natural Science Foundation of China (No. 21967021), the Foundation of China Tobacco Company [110202101004 (JY-04)], the Foundation of Yunnan Tobacco Industry Co. Ltd (No. 2021JC08), the opening foundation of Yunnan Key Laboratory of Tobacco Chemistry (No. 2019539200340162), and the Foundation of Yunnan Innovative Research Team (2019HC020).