Targeted Isolation of Indole Alkaloids from sp. CT37.

Four compounds (-) were isolated from the extracts of sp. CT37 using bioassay in conjunction with mass spectrometric molecular networking (MN) driven isolation. Their complete structures were established by high-resolution electrospray ionization mass spectrometry (HR-ESIMS), and 1D and 2D nuclear magnetic resonance (NMR) data. Legonimide was identified as a new alkaloid containing a rare linear imide motif in its structure, while compounds were already known and their structures were elucidated as 1H-indole-3-carbaldehyde, actinopolymorphol B, ()-1-phenylbutane-2,3-diol, respectively. The biosynthetic pathways of were proposed based on the reported biogenesis of indole alkaloids in literature. Bioactivity tests for and revealed moderate growth inhibition activity against ATCC 10231 with MIC values of 21.54 µg/mL and 11.47 µg/mL, respectively.