Synthesis and antitumor activity of alkylated bile acids and oxazolines

Chemical exploration of TGR5 functional hot-spots: Synthesis and structure-activity relationships of C7- and C23-Substituted cholic acid derivatives

The activation of TGR5 bestows on bile acids the ability to modulate nongenomic signaling pathways, which are responsible of physiological actions including immunosuppressive and anti-inflammatory properties as well as the regulation of glucose metabolism and energy homeostasis. TGR5 agonists have therefore emerged in drug discovery and preclinical appraisals as promising compounds for the treatment of liver diseases and metabolic syndrome. In this study, we have been devising site-selected chemical modifications of the bile acid scaffold to provide novel chemical tools able to modulate the functions of TGR5 in different tissues. Biological results of the tested collection of semisynthetic cholic acid derivatives were used to extend the structure-activity relationships of TGR5 agonists and to clarify the molecular basis and functional role of TGR5 hot-spots in the receptor activation and selectivity. Some unexpected properties deriving from the molecular structure of bile acids have been unveiled as relevant to the receptor activation and may hence be used to design novel, selective and potent TGR5 agonists.

How do different bile acid derivatives affect rat macrophage function - Friends or foes?

Due to an increased need for new immunomodulatory agents, many previously known molecules have been structurally modified in order to obtain new drugs, preserving at the same time some of the benevolent characteristics of the parent molecule. This study aimed to evaluate the immunomodulatory potential of a selected library of bile acid derivatives (BAD) using a broad spectrum of assays, evaluating rat peritoneal macrophages viability, cell membrane damage, lysosomal and adhesion function, and nitric oxide and cytokine production as a response to lipopolysaccharide stimulation. Also, in silico studies on two bile acid-activated receptors were conducted and the results were related to the observed in vitro effects. All tested BAD exerted significant toxicity in concentrations higher than 10 μM, which was determined based on mitochondria and cell membrane damage in a panel of assays. On the other hand, at lower concentrations, the tested BAD proved to be immunomodulatory since they affected lysosomal function, cell adhesion capacities and the ability to produce inflammatory cytokines in response to a stimulus. One of the compounds proved to exhibit significant toxicity toward macrophages, but also caused a concentration-dependent decrease in nitric oxide levels and was identified as a potential farnesoid X receptor agonist.

Efficacious One-pot Synthesis of 2-thiazolines and 2-oxazolines Under Solvent and Metal-Free Conditions

Background:

2-oxazolines and 2-thiazolines are important heterocycles due to their extensive applications in chemistry, biochemistry, and pharmacology. Most of the precedent methods for preparing these heterocycles involve one or more drawbacks, including harsh reaction conditions, long reaction times, low yields of products, high temperature, and toxic solvents.

Objective:

The aim of this study was to develop a new and eco-efficient method for the preparation of 2-oxazolines and 2-thiazolines.

Methods:

Amino alcohols were condensed with nitriles in a sealed tube under solvent-free and metal- free conditions.

Results:

Our procedure appears to be highly eco-efficient and promotes quantitative access to 2-oxazolines and 2-thiazolines using simple and minimum manipulation.

Conclusion:

This simple approach allows high conversion for different nitriles yielded from 78 to 99% and easy isolation of the targeted products without further purification. To the best of our knowledge, our procedure is the most efficient and fast method reported to date in terms of chemical yields, number of steps, and atom economy.

Synthesis of new bile acid-fused tetrazoles using the Schmidt reaction

A practical and high-yielding Schmidt reaction for the synthesis of fused tetrazoles from bile acid precursors was developed. Mild reaction conditions using TMSN₃ instead of hydrazoic acid as an azide source produced good yields of the desired tetrazoles. These conditions could be applied to other steroidal precursors. Additionally, an improved methodology for the synthesis of different ketone and enone precursors from cholic acid, deoxycholic acid, and chenodeoxycholic acid was established. Newly obtained tetrazole derivatives were characterized by NMR and X-ray diffraction spectroscopy. In a number of cases, preliminary antiproliferative tests of new compounds showed strong and selective activity towards certain tumor cell lines.