Novel hypolipidemic conjugates of fatty acid and bile acid with lysine for linkage.

Novel fatty acid-bile acid conjugates (1a-1k) were designed and synthesized by coupling of the fatty acids to the 3-OH of bile acids using lysine for linkage. In the conjugates, the 24-COOH of the bile acids was kept intact to preserve liver-specific recognition. The ability of the newly synthesized conjugates (at 100 mg/kg dosage) to reduce total cholesterol (TC) and triglyceride (TG) levels in mice fed with high-fat diet (HFD) was evaluated. Conjugates of stearic acid with cholic acid and palmitic acid with ursodeoxycholic acid (at dosages of 50, 100, and 200 mg/kg) were further evaluated to determine their ability to reduce aspartate aminotransferase (AST), alanine aminotransferase (ALT), TC, and TG levels in mice fed with HFD. All conjugates showed potent hypolipidemic activity. Further investigation revealed that compounds 1c and 1 g not only dose-dependently reduced serum levels of TC and TG, but also inhibited the elevation of serum AST and ALT levels in mice fed with HFD. Thus, compounds 1c and 1 g are promising hypolipidemic agents with hepatocyte protective effects against HFD-induced liver damage.

Synthesis of N,O,B-Chelated Dipyrromethenes through an Unexpected Intramolecular Cyclisation: Enhanced Near-Infrared Emission in the Aggregate/Solid State.

The first example of the synthesis of mono-N,O-B-chelated dipyrromethene (BODIPY) derivatives through an unexpected intramolecular nucleophilic displacement of the fluorine by alkenols in the presence of boron trifluoride as Lewis acid is reported. The chlorine in the indacene core allowed for further structural modifications through nucleophilic substitutions or palladium-catalysed coupling reactions to afford new fluorophores with tuneable photophysical properties. Their expanded conjugation structure resulted in distinct red-shifted absorption and emission spectra in organic solutions. Furthermore, the twisted steric hindrance of the benzene substitution patterns suppressed aggregation-induced quenching, leading to an enhanced NIR emission in the aggregate/solid state, which was rarely observed for BODIPY dyes. Nanoparticles of the fluorophores formed by the assembly with the polymeric surfactant F127 were successfully used for bioimaging of living cells and for tumour-targeted imaging in a tumour-bearing mouse model.