Physiochemical Tuning of Potent Escherichia coli Anti‐Adhesives by Microencapsulation and Methylene Homologation

Abstract

Thiazolylaminomannosides (TazMan) are FimH antagonists with anti‐adhesive potential against adherent‐invasive Escherichia coli (AIEC) promoting gut inflammation in patients with Crohn's disease. The lead TazMan is highly potent in vitro, but shows limited in vivo efficiency, probably due to low pH stability and water solubility. We recently developed a second generation of stable TazMan, but the anti‐adhesive effect was lower than the first. Herein we report a co‐crystal structure of the lead TazMan in FimH, revealing that the anomeric NH group and the second thiazole moiety provide a positive hydrogen bonding interaction with a trapped water molecule, and π‐stacking with Tyr48 of FimH, respectively. Consequently, we developed NeoTazMan homologated with a methylene group for low‐pH and mannosidase stability with a conserved NH group and bearing various heterocyclic aglycones. Microencapsulation of the lead NeoTazMan in γ‐cyclodextrin dramatically improved water solubility without disrupting the affinity for FimH or the anti‐adhesive effect against AIEC isolated from patients with Crohn's disease.

Sites for Dynamic Protein-Carbohydrate Interactions of O- and C-Linked Mannosides on the E. coli FimH Adhesin

“…In accordance with recent studies reporting that the FimH binding affinity and pharmacological characteristics of alkyl- and aryl α- d -mannopyranosides could be further improved by the insertion of extra substituents [ 9 , 16 , 17 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 29 ] substituting the para and ortho positions of the phenyl ring with an additional phenyl ring or inserting a naphthalene group most frequently surpassed the binding affinity of the unsubstituted phenyl derivative ( Table 5 ). The inhibition potential of 116 and 117 exceeds the one of their parent 115 some 4- and 26-fold, respectively, indicating additional interactions of the extra phenyl substituent in the tyrosine gate.…”

“…However, C -glycosides are of higher stability, because they are not metabolized by the host enzymes [ 18 , 29 , 30 ]. Earlier comparisons of the bioactivities of C -glycosides with those of their O -glycosylated parents have uncovered several candidates with diminished or similar activity [ 8 , 9 , 18 , 29 , 41 ], but none exhibiting a significant improvement. Modification of the O- linked α-anomer by a C -linkage leads to a loss in polar character and thus hydrogen bonding capacity [ 29 , 38 ].…”

“…Earlier comparisons of the bioactivities of C -glycosides with those of their O -glycosylated parents have uncovered several candidates with diminished or similar activity [ 8 , 9 , 18 , 29 , 41 ], but none exhibiting a significant improvement. Modification of the O- linked α-anomer by a C -linkage leads to a loss in polar character and thus hydrogen bonding capacity [ 29 , 38 ]. In the synthetic work presented here, it also implies a pharmacophore position shifting.…”

“…Due to its unique design, the FimH binding site accommodates rather well α- d -mannopyranosides substituted with apolar aglycons, making these compounds very potent FimH inhibitors. M annopyranosides α-substituted with heptyl [ 4 , 13 , 14 , 24 , 28 ] or with thiazolylamine [ 12 , 21 , 22 , 29 ] have been described as the most potent O -linked FimH ligands. However, O -linked compounds are possibly susceptible to degradation by glycosidases.…”

“…Low bioavailability and half-life of O -mannosides can be attributed to the metabolic instability of the O -glycosidic bond [ 11 , 18 ]) and the hydrolysis by mannosidases [ 30 , 31 ]. Substitution of the O -glycosidic linkage by a C -glycosidic linkage was recently shown to lend important advantages in the activity of mannose-based anti-adhesives on the elimination of E. coli of intestinal cells [ 29 ] as well as for the treatment of urinary tract infections [ 18 , 21 ]. para -Biphenyl derivatives O - and C -linked to α- d -mannopyranosides are under drug development [ 6 , 7 , 18 , 32 ].…”