Functional Regioregular (Poly)urethanes from Soft Nucleophiles and Cyclic Iminocarbonates

The catalyst-free synthesis of urethanes from cyclic iminocarbonates, used as masked isocyanates, and soft nucleophiles (i.e. carboxylic acids and thiols) has been studied. Remarkably, the ring-opening reaction occurred fully site-selective...

Epoxide functionalization on cholane side chains in the identification of G-protein coupled bile acid receptor (GPBAR1) selective agonists

Decoration of the bile acid side chain with an epoxide ring afforded potent and selective GPBAR1 agonists.

Navigation in bile acid chemical space: discovery of novel FXR and GPBAR1 ligands

Bile acids are signaling molecules interacting with nuclear receptors and membrane G-protein-coupled receptors. Among these receptors, the farnesoid X receptor (FXR) and the membrane G-coupled receptor (GPBAR1) have gained increasing consideration as druggable receptors and their exogenous dual regulation represents an attractive strategy in the treatment of enterohepatic and metabolic disorders. However, the therapeutic use of dual modulators could be associated to severe side effects and therefore the discovery of selective GPBAR1 and FXR agonists is an essential step in the medicinal chemistry optimization of bile acid scaffold. In this study, a new series of 6-ethylcholane derivatives modified on the tetracyclic core and on the side chain has been designed and synthesized and their in vitro activities on FXR and GPBAR1 were assayed. This speculation resulted in the identification of compound 7 as a potent and selective GPBAR1 agonist and of several derivatives showing potent dual agonistic activity.

Insights on FXR selective modulation. Speculation on bile acid chemical space in the discovery of potent and selective agonists

Bile acids are the endogenous modulators of the nuclear receptor FXR and the membrane receptor GPBAR1. FXR represents a promising pharmacological target for the treatment of cholestatic liver disorders. Currently available semisynthetic bile acid derivatives cover the same chemical space of bile acids and therefore they are poorly selective toward BA receptors, increasing patient risk for adverse side effects. In this report, we have investigated around the structure of CDCA describing the synthesis and the in vitro and in vivo pharmacological characterization of a novel family of compounds modified on the steroidal tetracyclic core and on the side chain. Pharmacological characterization resulted in the identification of several potent and selective FXR agonists. These novel agents might add utility in the treatment of cholestatic disorders by potentially mitigating side effects linked to unwanted activation of GPBAR1.

Investigation on bile acid receptor regulators. Discovery of cholanoic acid derivatives with dual G-protein coupled bile acid receptor 1 (GPBAR1) antagonistic and farnesoid X receptor (FXR) modulatory activity

Bile acids, the end products of cholesterol metabolism, activate multiple mechanisms through the interaction with membrane G-protein coupled receptors including the bile acid receptor GPBAR1 and nuclear receptors such as the bile acid sensor, farnesoid X receptor (FXR). Even if dual FXR/GPBAR1 agonists are largely considered a novel opportunity in the treatment of several liver and metabolic diseases, selective targeting of one of these receptors represents an attractive therapeutic approach for a wide range of disorders in which dual modulation is associated to severe side effects. In the present study we have investigated around the structure of LCA generating a small library of cholane derivatives, endowed with dual FXR agonism/GPBAR1 antagonism. To the best of our knowledge, this is the first report of bile acid derivatives able to antagonize GPBAR1.

Modification on ursodeoxycholic acid (UDCA) scaffold. discovery of bile acid derivatives as selective agonists of cell-surface G-protein coupled bile acid receptor 1 (GP-BAR1)

Bile acids are signaling molecules interacting with the nuclear receptor FXR and the G-protein coupled receptor 1 (GP-BAR1/TGR5). GP-BAR1 is a promising pharmacological target for the treatment of steatohepatitis, type 2 diabetes, and obesity. Endogenous bile acids and currently available semisynthetic bile acids are poorly selective toward GP-BAR1 and FXR. Thus, in the present study we have investigated around the structure of UDCA, a clinically used bile acid devoid of FXR agonist activity, to develop a large family of side chain modified 3α,7β-dihydroxyl cholanoids that selectively activate GP-BAR1. In vivo and in vitro pharmacological evaluation demonstrated that administration of compound 16 selectively increases the expression of pro-glucagon 1, a GP-BAR1 target, in the small intestine, while it had no effect on FXR target genes in the liver. Further, compound 16 results in a significant reshaping of bile acid pool in a rodent model of cholestasis. These data demonstrate that UDCA is a useful scaffold to generate novel and selective steroidal ligands for GP-BAR1.