Jejucarbazoles A-C, Carbazole Glycosides With Indoleamine 2,3-Dioxygenase 1 Inhibitory Activity From Streptomyces Sp. Kcb15ja151

A bioassay-guided investigation led to the isolation of three new carbazole glycosides, jejucarbazoles A-C (1-3), from Streptomyces sp. KCB15JA151. Their planar structures were elucidated by detailed NMR and MS spectroscopic analysis with a literature study. Their relative and absolute configurations were established by ROESY correlations, coupling constants, LC-MS analysis of thiocarbamoyl-thiazolidine carboxylate derivatives, and ECD calculation. Compounds 1-3 showed indoleamine 2,3-dioxygenase 1 (IDO1) inhibitory activity with IC50 values of 18.38, 9.17, and 8.81 mu M. The molecular docking analysis suggested that all compounds act as heme-displacing inhibitors against IDO1 enzyme.