Benzopyrimido‐pyrrolo‐oxazine‐dione CFTR inhibitor (R)‐BPO‐27 for antisecretory therapy of diarrheas caused by bacterial enterotoxins

Abstract

Secretory diarrheas caused by bacterial enterotoxins, including cholera and traveler's diarrhea, remain a major global health problem. Inappropriate activation of the cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel occurs in these diarrheas. We previously reported that the benzopyrimido-pyrrolo-oxazinedione (R)-BPO-27 inhibits CFTR chloride conductance with low-nanomolar potency. Here, we demonstrate using experimental mouse models and human enterocyte cultures the potential utility of (R)-BPO-27 for treatment of secretory diarrheas caused by cholera and Escherichia coli enterotoxins. (R)-BPO-27 fully blocked CFTR chloride conductance in epithelial cell cultures and intestine after cAMP agonists, cholera toxin, or heat-stable enterotoxin of E. coli (STa toxin), with IC down to ∼5 nM. (R)-BPO-27 prevented cholera toxin and STa toxin-induced fluid accumulation in small intestinal loops, with IC down to 0.1 mg/kg. (R)-BPO-27 did not impair intestinal fluid absorption or inhibit other major intestinal transporters. Pharmacokinetics in mice showed >90% oral bioavailability with sustained therapeutic serum levels for >4 h without the significant toxicity seen with 7-d administration at 5 mg/kg/d. As evidence to support efficacy in human diarrheas, (R)-BPO-27 blocked fluid secretion in primary cultures of enteroids from human small intestine and anion current in enteroid monolayers. These studies support the potential utility of (R)-BPO-27 for therapy of CFTR-mediated secretory diarrheas.-Cil, O., Phuan, P.-W., Gillespie, A. M., Lee, S., Tradtrantip, L., Yin, J., Tse, M., Zachos, N. C., Lin, R., Donowitz, M., Verkman, A. S. Benzopyrimido-pyrrolo-oxazine-dione CFTR inhibitor (R)-BPO-27 for antisecretory therapy of diarrheas caused by bacterial enterotoxins.

Nanomolar-Potency Aminophenyl-1,3,5-triazine Activators of the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) Chloride Channel for Prosecretory Therapy of Dry Eye Diseases

“…8 Activators of wild-type CFTR have potential clinical indications for prosecretory therapy of constipation and dry eye disorders and possibly for disorders of the liver, pancreas, and airways, 9–12 and CFTR inhibitors are under development for certain secretory diarrheas and polycystic kidney disease. 13,14 …”

Palladium-Catalyzed Intramolecular Cyclization: Access to Rare PentacyclicN-Fused Heterocycles

“…Particularly, the condensed 1–2 fused pyrrole derivatives are of enormous interest because of their broad cytotoxic activity such as anti cancer (e. g. lamellarines I , chlorizidine II ), and antimalarial activity (e. g. flinderole C III ) . Figure depicts the representative bioactive 1–2 fused pyrrole derivatives 1 ‐ IV …”

Reply from L. P. Cid, T. J. Jentsch and F. V. Sepúlveda: intestinal electrolyte and fluid secretion – a model in trouble?

“…3 of the paper by Cil et al . (). These show quite clearly that a marked increase in the volume of fluid within the intestinal lumen has taken place after treatment with STa.…”

“…The contribution of this NHE3 inhibition also appears minor judged by experiments in which the increase in intraluminal fluid accumulation of mouse jejunum under the effect of STa, very much as that induced by cholera toxin, is abolished using a highly specific inhibitor of CFTR (Cil et al . ). The same inhibitor abolishes the increase in short‐circuit current evoked by STa across the jejunum in vitro .…”

“…Just to cite the most recent such demonstration we are aware of, Cil et al . () used a jejunal closed loop approach in the mouse to show that STa evokes an important intraluminal accumulation of fluid that is measured as increase in loop weight at the end of the experiment. To convince oneself that this is genuine increase in intraluminal fluid, and is not due to ‘increased extracellular volume’, it might be enlightening to examine the photographs of the intestinal loops under the various conditions in Fig.…”