AUTHOR=Shen Ling , Liu Mengting , He Yan , Al Anbari Weaam Hasan , Li Huaqiang , Lin Shuang , Chai Chenwei , Wang Jianping , Hu Zhengxi , Zhang Yonghui 

TITLE=Novel Antimicrobial Compounds as Ophiobolin-Type Sesterterpenes and Pimarane-Type Diterpene From Bipolaris Species TJ403-B1

JOURNAL=Frontiers in Microbiology

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2020.00856

DOI=10.3389/fmicb.2020.00856

ISSN=1664-302X

ABSTRACT=<p>Six previously undescribed ophiobolin-type sesterterpenes, namely, bipolatoxins A–F (<bold>1</bold>–<bold>6</bold>); and one previously undescribed pimarane-type diterpene, namely, 1β-hydroxy momilactone A (<bold>7</bold>); together with three known compounds, namely, 25-hydroxyophiobolin I (<bold>8</bold>), ophiobolin I (<bold>9</bold>), and ophiobolin A lactone (<bold>10</bold>); were isolated and identified from the endophytic fungus <italic>Bipolaris</italic> species TJ403-B1. Their structures with absolute configurations were elucidated on the basis of extensive spectroscopic analyses (including 1D and 2D nuclear magnetic resonance (NMR) and high-resolution electrospray ionization mass spectroscopy data), single-crystal X-ray diffraction analyses, and comparison of experimental circular dichroism data. All compounds (except for <bold>5</bold>) were evaluated for antimicrobial potential, which indicated that bipolatoxin D (<bold>4</bold>) showed significant inhibitory activity against <italic>Enterococcus faecalis</italic> with a minimum inhibitory concentration (MIC) value of 8 μg/mL, and ophiobolin A lactone (<bold>10</bold>) showed significant inhibitory activity against <italic>Acinetobacter baumannii</italic> and <italic>E. faecalis</italic> with MIC values of 8 and 8 μg/mL, respectively.</p>