Structural characterization of new pyrrolic compounds produced by Streptomyces coelicoflavus MFB strains with evaluation of their antiproliferative and antibacterial effects

Bacterial pigments like the bi-pyrrolic Tambjamines (TMj) and tri-pyrrolic Prodiginines (PGs) are biosynthesized through similar metabolic pathways with a shared route that bifurcates to generate diverse molecules belonging to these families. The responsible enzymes have the flexibility to create many variable structures of PGs and TMj among the producer species. These compounds have potent bioactivities and have inspired the development of new clinical drugs. Herein, we report the isolation and characterization of pyrrolic compounds similar to the PGs and TMj from Streptomyces coelicoflavus strains (MFB11, MFB20, MFB23, and MFB24). The new compounds were characterized through mass spectroscopy, 1 H-NMR, 13 C-NMR, and DEPT-135 analysis as novel molecules: butyl-bi-ethoxy-pyrrole (FB1) and bi-ethoxy-prodiginine (FB2). The two compounds showed potent antibacterial activity, with FB2 being active against M. luteus, S. aureus, and B. subtilis , while FB1 demonstrated activity against B. subtilis . Also, they exerted apoptotic effects against the P3X63Ag8 resistant cell line (through Bcl-xl overexpression) with IC 50 values of 45.6 μM and 63.02 μM, for FB2 and FB1, respectively. Furthermore, molecular docking of the novel structures against Bcl-xl showed that they bind with good affinity (-5.9 kcal mol −1 and -5.5 kcal mol −1 ) to the key BH3 domain targeted by standard anticancer drugs. The new bioorganic molecules could be exploited for medical use as antibacterials and/or anticancer drugs. • Pigments from Streptomyces coelicoflavus were isolated and purified by column chromatography. • Compound structures were analyzed using GC-MS, FTIR, UV-Vis spectroscopy, and NMR. • Two new pyrrolic prodiginine-family molecules were identified and characterized. • The compounds showed strong antibacterial, antiproliferative, and BH3-mimetic activities.