identification of novel coumestan derivatives as Mycobacterium tuberculosis ( Mtb) Pks13-thioesterase (TE) domain inhibitors, with mutations observed (D1644G and N1640K) in the generated coumestan-resistant Mtb colonies. Herein, we report a further structure-activity relationships exploration exploiting the available Pks13-TE X-ray co-crystal structure that resulted in the discovery of extremely potent coumestan