Substrate Fragmentation for the Design of M. tuberculosis CYP121 Inhibitors

Abstract

The cyclo‐dipeptide substrates of the essential M. tuberculosis (Mtb) enzyme CYP121 were deconstructed into their component fragments and screened against the enzyme. A number of hits were identified, one of which exhibited an unexpected inhibitor‐like binding mode. The inhibitory pharmacophore was elucidated, and fragment binding affinity was rapidly improved by synthetic elaboration guided by the structures of CYP121 substrates. The resulting inhibitors have low micromolar affinity, good predicted physicochemical properties and selectivity for CYP121 over other Mtb P450s. Spectroscopic characterisation of the inhibitors′ binding mode provides insight into the effect of weak nitrogen‐donor ligands on the P450 heme, an improved understanding of factors governing CYP121–ligand recognition and speculation into the biological role of the enzyme for Mtb.

Biophysical Screening of a Focused Library for the Discovery of CYP121 Inhibitors as Novel Antimycobacterials

“…[11,15] Kavanagh et al designed compounds based on substrate fragmentation with micromolar affinity and selectivity over other Mtb P450'sw ithout data concerning biological activity. [16] Regarding compounds with cellular activity, it was shown that azole antifungals bind tightlyt oCYP121and exhibit an in vitro and in vivo activity against Mtb. [17][18][19][20][21][22] Furthermore, the bindingt ot he enzyme was in good correlation with the antimycobacterial effect.…”

Design and Synthesis of Bioisosteres of Acylhydrazones as Stable Inhibitors of the Aspartic Protease Endothiapepsin

“…The ester ( S )‐ 3 was accessible through the Steglich esterification . We synthesized the bioisostere ( S )‐ 4 from the building blocks thioamide ( S )‐ 7 and ketobromide 9 , which can be both accessed in two steps from N ‐α‐Boc‐ l ‐tryptophan ( 5 ) and mesitylacetic acid ( 8 ), respectively.…”

A new strategy for hit generation: Novel in cellulo active inhibitors of CYP121A1 from Mycobacterium tuberculosis via a combined X-ray crystallographic and phenotypic screening approach (XP screen)

“…As part of continuing efforts aimed at the discovery of novel inhibitors of CYP121A1 [ [8] , [9] , [10] ], the binding mode of a novel class of inhibitors with moderate activity against Mtb strain H37Rv was reinvestigated. Previous work had shown that a series of d -tryptophan derived thiazoles exhibited moderate potency ( K d ∼ 30–55 μM) against CYP121A1 in a UV–Vis spectrophotometric assay [ 10 ]. Some members of the series ( Fig.…”