Subtipyrrolines A-C, novel bioactive alkaloids from the Mariana Trench-associated bacterium Bacillus subtilis SY2101

The new subtipyrrolines A-C were discovered from the hadal bacterium Bacillus subtilis SY2101 isolated from a sample of sediment collected at the Mariana Trench. Their structures were elucidated based on the HRESIMS data, extensive NMR spectroscopic analyses, ECD and C-13 NMR calculations, and single crystal X-ray diffraction experiment. Subtipyrrolines A-C possessed an unprecedented pyrrole-pyrrole-dihydropyridine tricyclic skeleton. Subtipyrrolines A and C showed weak antiproliferative activities against human glioma U251 and U87MG cells, respectively, and subtipyrrolines A-C had weak antimicrobial activities in inhibiting the growth of Escherichia coli and Candida albicans. The plausible biosynthetic pathway of subtipyrrolines A-C was also proposed. (C) 2020 Elsevier Ltd. All rights reserved.