Discovery of fernane type triterpenoids from Diaporthe discoidispora by using genome mining and HSQC-based SMART technology

Endophytic fungi have attracted increasing attention, because fascinating compounds with great therapeutic value have been isolated from these largely microbes. Fernane type triterpenoids were a rare of triterpenoids, which showed a variety of biological activities. Herein, we developed a genome mining and HSQC-based SMART technology in search of fernane type triterpenoids. Firstly, the potential endophytic fungi were found out by genome mining. Then the fine fractions, which contained variety of fernane type triterpenoids, were selected by HSQC data collection and SMART prediction. And then, those triterpenoids were obtained by target isolation and identification. At last, the antifungal activity was evaluated. As a result, one potential strain Diaporthe discoidispora was selected by genome mining, the fraction 3.4 was further isolated by various chromatographic methods, and then three fernane type triterpenoids, including two new ones, were isolated and identified along with two new sesquiterpenes and four known compounds. Their structures were elucidated by analysis of HRMS and NMR spectroscopic data. The absolute configurations were determined using single-crystal X-ray diffraction analysis, and ECD analysis. At last, the antifungal activities of the isolated compounds were evaluated. Compound 3 exhibited moderate antifungal activity towards Candida albicans CMCC 98001 and Aspergillus niger.