Synthesis, in vitro and in vivo biological evaluation of new oxysterols as modulators of the liver X receptors

In search for novel liver X receptors modulators by extending the structure-activity relationships of cholenamide derivatives

N,N-Dimethyl 3β-hydroxychol-5-en-24-amide (DMHCA, 3) is the prototype of cholenamides, a class of steroidal LXR modulators characterized by the nucleus of Δ5-cholen-3β-ol and the presence of an amide moiety at C-24. DMHCA (3) has been reported to act as a gene-selective modulator able to fully induce ABCA1 expression whilst poorly up-regulate the expression of FASN and SREBP-1α genes. With the aim to widen the limited structure-activity relationships of DMHCA (3), herein we describe the synthesis and the biological evaluation of nine novel derivatives, resulting from a) the homologation of DMHCA's side-chain to give N,N-dimethyl 3β-hydroxy-24a-homochol-5-en-24a-amide (4); b) the distal branching of the side-chain of 3 and 4 by introducing an ethyl group at C-23 and C-24, respectively; c) the replacement of the dimethyl amide moiety of all the derivatives with a carboxylic acid function. While broadening the structure-activity relationships of the class of cholenamides, we were successful in the discovery of (24R)-N,N-dimethyl-24-ethyl-3β-hydroxy-24a-homochol-5-en-24a-amide (6) as a novel LXR agonist with improved profile in term of selective gene modulation respect to the prototype DMHCA (3); indeed, 6 was able to up-regulate the expression of ABCA1 more than DMHCA (3), without to induce SREBP-1c, differently from DMHCA (3). Moreover, 6 induced the expression of FASN less than 3 and interestingly was a negative modulator towards SCD1 in contrast to DMHCA (3), which instead weakly induced the expression of this gene.

Emerging targets and potential therapeutic agents in non-alcoholic fatty liver disease treatment

Nonalcoholic Fatty Liver Disease (NAFLD) is the most common chronic liver disease in the world, which is characterized by liver fat accumulation unrelated to excessive drinking. Indeed, it attracts growing attention and becomes a global health problem. Due to the complexity of the NAFLD pathogenic mechanism, no related drugs were approved by Food and Drug Administration (FDA) till now. However, it is encouraging that a series of candidate drugs have entered the clinical trial stage with expectation to treat NAFLD. In this review, we summarized the main pathways and pathogenic mechanisms of NAFLD, as well as introduced the main potential therapeutic targets and the corresponding compounds involved in metabolism, inflammation and fibrosis. Furthermore, we also discuss the progress of these compounds, such as drug design and optimization, the choice of pharmacological properties and druglikeness, and the analysis of structure-activity relationship. This review offers a medium on future drug design and development, to be beneficial to relevant studies.

Regulation of liver X receptor target genes by 22-functionalized oxysterols. Synthesis, in silico and in vitro evaluations

The endogenous oxysterol 22(R)-hydroxycholesterol (22RHC, 1) is an LXR agonist which upregulates genes of critical involvement in human cholesterol- and lipid metabolism. In contrast, its synthetic epimer 22(S)-hydroxycholesterol (22SHC, 8) has shown specific antagonistic effects in recent studies, avoiding unwanted side effects provided by potent LXR agonists. In terms of LXR modulation, the aim of this study was to compare 22SHC (8), 22RHC (1) and synthesized ligands with keto- and amide functionality in the 22nd position of the cholesterol scaffold. 22SHC (8) and 22RHC (1) performed as expected while 22-ketocholesterol (22KC, 10) revealed an attractive in vitro profile for further investigation in terms of anti-atherosclerotic properties as selective upregulation of the ATP-binding cassette transporter ABCA1 was observed. A new synthesized amide derivate, Fernholtz cyclohexylamide (13) was shown to reduce lipogenesis in a dose-responsive manner and abolish the effect of the potent LXR agonist T0901317 when administered simultaneously.