Development and in†vitro Profiling of Dual FXR/LTA4H Modulators.

Designed polypharmacology presents as an attractive strategy to increase therapeutic efficacy in multi-factorial diseases by a directed modulation of multiple involved targets with a single molecule. Such an approach appears particularly suitable in non-alcoholic steatohepatitis (NASH) which involves hepatic steatosis, inflammation and fibrosis as pathological hallmarks. Among various potential pharmacodynamic mechanisms, activation of the farnesoid X receptor (FXRa) and inhibition of leukotriene A4 hydrolase (LTA4Hi) hold promise to counteract NASH according to preclinical and clinical observations. We have developed dual FXR/LTA4H modulators as pharmacological tools, enabling evaluation of this polypharmacology concept to treat NASH and related pathologies. The optimized FXRa/LTA4Hi exhibits well-balanced dual activity on the intended targets with sub-micromolar potency and is highly selective over related nuclear receptors and enzymes rendering it suitable as tool to probe synergies of dual FXR/LTA4H targeting.

Lipid accumulation inhibitory activities of novel isoxazole-based chenodeoxycholic acids: Design, synthesis and preliminary mechanism study.

In continuation of our drug discovery program on hyperlipidemia, a series of novel isoxazole-chenodeoxycholic acid hybrids were designed, synthesized and evaluated for their lipid-lowering effects. Preliminary screening of all the synthesized compounds was done by using a 3T3-L1 adipocyte model, in which the most active compound 16b could significantly reduce the lipid accumulation up to 30.5% at a nontoxic concentration 10 µM. Further mechanism studies revealed that 16b blocked lipid accumulation via activating FXR-SHP signaling pathway, efficiently down-regulated the expression of key lipogenesis regulator SREBP-1c.

Synthesis, in vitro and in vivo small-animal SPECT evaluation of novel technetium labeled bile acid analogues to study (altered) hepatic transporter function.

INTRODUCTION: Hepatobiliary transport mechanisms are crucial for the excretion of substrate toxic compounds. Drugs can inhibit these transporters, which can lead to drug-drug interactions causing toxicity. Therefore, it is important to assess this early during the development of new drug candidates. The aim of the current study is the (radio)synthesis, in vitro and in vivo evaluation of a technetium labeled chenodeoxycholic and cholic acid analogue: [(99m)Tc]-DTPA-CDCA and [(99m)]Tc-DTPA-CA, respectively, as biomarker for disturbed transporter functionality. METHODS: [99mTc]-DTPA-CDCA([(99m)Tc]-3a) and [99mTc]-DTPA-CA ([(99m)Tc]-3b) were synthesized and evaluated in vitro and in vivo. Uptake of both tracers was investigated in NTCP, OCT1, OATP1B1, OATP1B3 transfected cell lines. Km and Vmax values were determined and compared to [(99m)Tc]-mebrofenin ([(99m)Tc]-MEB). Efflux was investigated by means of CTRL, MRP2 and BSEP transfected inside-out vesicles. Metabolite analysis was performed using pooled human liver S9. Wild type (n=3) and rifampicin treated (n=3) mice were intravenously injected with 37MBq of tracer. After dynamic small-animal SPECT and short CT acquisitions, time-activity curves of heart, liver, gallbladder and intestines were obtained. RESULTS: We demonstrated that OATP1B1 and OATP1B3 are the involved uptake transporters of both compounds. Both tracers show a higher affinity compared to [(99m)Tc]-MEB, but are in a similar range as endogenous bile acids for OATP1B1 and OATP1B3. [(99m)Tc]-3a shows higher affinities compared to [(99m)Tc]-3b. Vmax values were lower compared to [(99m)Tc]-MEB, but in the same range as endogenous bile acids. MRP2 was identified as efflux transporter. Less than 7% of both radiotracers was metabolized in the liver. In vitro results were confirmed by in vivo results. Uptake in the liver and efflux to gallbladder + intestines and urinary bladder of both tracers was observed. Transport was inhibited by rifampicin. CONCLUSION: The involved transporters were identified; both tracers are taken up in the hepatocytes by OATP1B1 andOATP1B3 with Km and Vmax values in the same range as endogenous bile acids and are secreted into bile canaliculi via MRP2. Dynamic small-animal SPECT imaging can be a useful noninvasive method of visualizing and quantifying hepatobiliary transporter functionality and disturbances thereof in vivo, which could predict drug pharmacokinetics.

First synthesis of 22-oxa-chenodeoxycholic acid analogue.

In this study, we report the first synthesis of 22-oxa-chenodeoxycholic acid analogue via androstenedione and progesterone, in 11 and 8 steps with overall yields of 6.4% and 12.7%, respectively. We anticipate this will help to facilitate the development of new drugs.

Conicasterol E, a small heterodimer partner sparing farnesoid X receptor modulator endowed with a pregnane X receptor agonistic activity, from the marine sponge Theonella swinhoei.

We report the isolation and pharmacological characterization of conicasterol E isolated from the marine sponge Theonella swinhoei. Pharmacological characterization of this steroid in comparison to CDCA, a natural FXR ligand, and 6-ECDCA, a synthetic FXR agonist generated by an improved synthetic strategy, and rifaximin, a potent PXR agonist, demonstrated that conicasterol E is an FXR modulator endowed with PXR agonistic activity. Conicasterol E induces the expression of genes involved in bile acids detoxification without effect on the expression of small heterodimer partner (SHP), thus sparing the expression of genes involved in bile acids biosynthesis. The relative positioning in the ligand binding domain of FXR, explored through docking calculations, demonstrated a different spatial arrangement for conicasterol E and pointed to the presence of simultaneous and efficient interactions with the receptor. In summary, conicasterol E represents a FXR modulator and PXR agonist that might hold utility in treatment of liver disorders.

Efficacy on anaplastic thyroid carcinoma of valproic acid alone or in combination with doxorubicin, a synthetic chenodeoxycholic acid derivative, or lactacystin.

The present study investigated the mechanism underlying the antitumor activity of the histone deacetylases inhibitor valproic acid (VPA), alone and in combination with doxorubicin, a synthetic chenodeoxycholic acid derivative (HS-1200), or the proteasome inhibitor lactacystin on cultured anaplastic thyroid carcinoma KAT-18 cells. Cell viability was evaluated by trypan-blue exclusion. Western blotting determined caspase and histone deacetylase activities and expression of poly(ADP)-ribose polymerase. Induction of apoptosis was identified by Hoechst staining, DNA electrophoresis, DNA hypoploidy and cell cycle phase analysis, and measurement of mitochondrial membrane potential. Subcellular translocation of apoptosis inducing factor and caspase-activated DNase after treatment was determined by confocal microscopy following immunofluorescent staining. VPA treatment increased apoptotic death of KAT-18 cells. VPA treatment was also associated with degradation of procaspase-3, procaspase-7, and poly(ADP)-ribose polymerase; induction of histone hyperacetylation; condensation of peripheral chromatin; decreased mitochondrial membrane potential and DNA content; and decreased translocation of apoptosis inducing factor and caspase-activated DNase. VPA in combination with doxorubicin, HS-1200, or lactacystin, applied at the highest concentrations that did not induce KAT-18 cell death, efficiently induced apoptosis in KAT-18 cells. The results suggest VPA combination therapy may represent an alternative therapeutic strategy for anaplastic thyroid carcinoma.

New lithocholic and chenodeoxycholic piperazinylcarboxamides with antiproliferative and pro-apoptotic effects on human cancer cell lines.

Six new synthetic bile acid derivatives were synthesized and tested in vitro against various human cancer cells (glioblastoma multiforme (GBM), multiple myeloma (KMS-11), and colonic carcinoma (HCT-116) cell lines. The best activity was obtained with compound IIIb on multiple myeloma cells (LD(50): 8.5+/-0.5 microM). This activity was associated with Mcl-1 and PARP-1 cleavage, inhibition of NFkappaB signaling, and DNA fragmentation, demonstrating an apoptotic cell death signaling pathway.

Back door modulation of the farnesoid X receptor: design, synthesis, and biological evaluation of a series of side chain modified chenodeoxycholic acid derivatives.

Carbamate derivatives of bile acids were synthesized with the aim of systematically exploring the potential for farnesoid X receptor (FXR) modulation endowed with occupancy of the receptor's back door, localized between loops H1-H2 and H4-H5. Since it was previously shown that bile acids bind to FXR by projecting the carboxylic tail opposite the transactivation function 2 (AF-2, helix 12), functionalization of the side chain is not expected to interfere directly with the orientation of H12 but can result in a more indirect way of receptor modulation. The newly synthesized compounds were extensively characterized for their ability to modulate FXR function in a variety of assays, including the cell-free fluorescence resonance energy transfer (FRET) assay and the cell-based luciferase transactivation assay, and displayed a broad range of activity from full agonism to partial antagonism. Docking studies clearly indicate that the side chain of the new derivatives fits in a so far unexploited receptor cavity localized near the "back door" of FXR. We thus demonstrate the possibility of achieving a broad FXR modulation without directly affecting the H12 orientation.