Imidazolium Salts as Small-Molecule Urinary Bladder Exfoliants in a Murine Model

Abstract

dWe present a novel family of small-molecule urinary bladder exfoliants that are expected to be of great value in preclinical studies of urologic conditions and have improved potential for translation compared with prior agents. There is broad urologic interest in the therapeutic potential of such exfoliating agents. The primary agent used in preclinical models, the cationic peptide protamine sulfate (PS), has limited translational potential due to concerns including systemic adverse reactions and bladder tissue injury. Intravesical application of a safe, systemically nontoxic exfoliant would have potential utility in the eradication of Escherichia coli and other uropathogens that reside in the bladder epithelium following cystitis, as well as in chronic bladder pain and bladder cancer. Here, we introduce a family of imidazolium salts with potent and focused exfoliating activity on the bladder epithelium. Synthesis and purification were straightforward and scalable, and the compounds exhibited prolonged stability in lyophilized form. Most members of the compound family were cytotoxic to cultured uroepithelial cells, with >10-fold differences in potency across the series. Upon topical (intravesical) administration of selected compounds to the murine bladder, complete epithelial exfoliation was achieved with physiologically relevant imidazolium concentrations and brief contact times. The exfoliative activity of these compounds was markedly improved in comparison to PS, as assessed by microscopy, immunofluorescence, and immunoblotting for uroplakins. Bladder uroepithelium regenerated within days to yield a histologically normal appearance, and no toxicity was observed. Finally, the chemical scaffold offers an opportunity for inclusion of antimicrobials or conjugation with chemotherapeutic or other moieties.

Synthesis, anti-proliferative activity, SAR study, and preliminary in vivo toxicity study of substituted N,N′-bis(arylmethyl)benzimidazolium salts against a panel of non-small cell lung cancer cell lines

“…[9] Upon removal of a precipitate, a second equivalent of 2-(chloromethyl)quinoline was added and the mixture was heated at reflux overnight to produce the corresponding salts in moderate yields (Equation 8). Compounds 24 and 25 were characterized by 1 H NMR and 13 C NMR spectroscopy and high resolution mass spectrometry.…”

“…[9] Cyclization of commercially available o-phenylenediamine and 4,5-dimethylbenzene-1,2-diamine with 2-(2-(2-methoxyethoxy)ethoxy)acetic acid generated the benzimidazole intermediates 26 and 27 , which were then alkylated with 2-(bromomethyl)-naphthalene or 2-(chloromethyl)quinoline in a two-step process to yield the 28 , 30 , and 31 in yields ranging from 20 to 52 %. Compounds 28 , 30 , and 31 were characterized by 1 H NMR and 13 C NMR spectroscopy and elemental analysis.…”

“…[8] 2-((2-(2-Methoxyethoxy)ethoxy)methyl)benzimidazole ( 26 ) was synthesized according to literature procedure. [9]Column chromatography utilized silica gel (60 Å, ICN Medicals) embedded with fluorescent indicator green 254 nm (Fluka Analytical). Melting points were obtained on a MelTemp apparatus.…”

Urinary Tract Infection: Pathogenesis and Outlook

“…Further, as the bladder exfoliation accompanying acute UPEC cystitis is not complete, bacteria within quiescent reservoirs may re-emerge to seed recurrent infection. Advanced, more efficacious exfoliants are being designed to unearth these quiescent reservoirs [93, 94]. Once these bacteria are forced to emerge, they may be more susceptible to the actions of standard antibiotics.…”

Invasion of Host Cells and Tissues by Uropathogenic Bacteria

“…In this case, a bladder cell exfoliant such as chitosan or imidazolium salts is instilled into the bladder lumen, triggering the rapid release of umbrella cells and the subsequent proliferation and differentiation of newly exposed immature uroepithelial cells (150, 197, 198). This process eradicates any reservoir populations that may be present within the superficial layer of bladder cells, but also induces the resurgence of UPEC from less mature uroepithelial cells as they differentiate and realign their actin filaments (29).…”