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=

Six previously undescribed ophiobolin-type sesterterpenes, namely, bipolatoxins A–F (16); and one previously undescribed pimarane-type diterpene, namely, 1β-hydroxy momilactone A (7); together with three known compounds, namely, 25-hydroxyophiobolin I (8), ophiobolin I (9), and ophiobolin A lactone (10); were isolated and identified from the endophytic fungus Bipolaris 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 5) were evaluated for antimicrobial potential, which indicated that bipolatoxin D (4) showed significant inhibitory activity against Enterococcus faecalis with a minimum inhibitory concentration (MIC) value of 8 μg/mL, and ophiobolin A lactone (10) showed significant inhibitory activity against Acinetobacter baumannii and E. faecalis with MIC values of 8 and 8 μg/mL, respectively.