Two new alkaloids from a strain of endophytic fungus Aspergillus sp.

Abstract

19-Hydroxybrevianamide M (1) and 6 R-methoxybrevianamide V (2), two new alkaloids, were isolated from an extract of the endophytic fungus Aspergillus sp. JNU18HC0517J, together with six known analogues (3– 8). Their structures were elucidated by extensive spectroscopic analyses, NMR calculations, and ECD calculations. 6 R-methoxybrevianamide V (2) was the first L-proline indole DKP alkaloid with substitution at C-6 on the proline ring. Furthermore, the cytotoxities and antimicrobial activities of these isolated compounds were also evaluated. Compound 8 exhibited moderate antibacterial activity against Staphylococcus aureus 209 P with a minimal inhibitory concentration (MIC) value of 16 µg/ml.

Keywords:

• Endophytic fungus
• Aspergillus sp.
• diketopiperazine alkaloids

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was financially supported by the National Key Research and Development Program of China [No. 2018YFA0903200//2018YFA0903201], the National Natural Science Foundation of China [Nos. 81925037 and 81973213], National High-level Personnel of Special Support Program [No. 2017RA2259], the 111 Project of Ministry of Education of China [No. B13038], Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program [No. 2017BT01Y036], Guangdong International Science and Technology Cooperation Base [No. 2021A0505020015], Innovative and Research Teams Project of Guangdong Higher Education Institution [No. 2021KCXTD001], Natural Science Foundation of Guangdong [No. 2022A1515012041], K. C. Wong Education Foundation [No. Guo-Dong Chen, 2021, China], the Science and Technology Planning Project of Guangzhou [No. 202201020048], the Undergraduates Innovation Project of Jinan University [No. CX21231], and the Postgraduates Innovation Project of Jinan University [No. 2021CXB001].