Amélie Barczyk

4-Oxo-1,4-dihydropyridines as selective CB₂ cannabinoid receptor ligands. Part 2: discovery of new agonists endowed with protective effect against experimental colitis

Further on to our earlier work on the 4-oxo-1,4-dihydropyridine, we describe herein our strategy to get access to potent selective CB₂ receptor agonists. Thus, we designed and synthesized 29 compounds, evaluated on both hCB₁ and hCB₂ cannabinoid receptors, and assessed 11 of them in the TNBS-induced colitis model in mice. Compound 48 was found to be the most efficient of our series, exhibiting an exquisite protection against experimental colitis, superior to the one observed after treatment with Pentasa.

Design, synthesis and biological evaluation of potent FAAH inhibitors

A new series of 3-carboxamido-5-aryl-isoxazoles was designed, synthesized and evaluated for their biological activity. Different pharmacomodulations have been explored and the lipophilicity of these compounds was assessed. Investigation of the in vitro biological activity led to the identification of 5 compounds as potent FAAH inhibitors, their good FAAH inhibition capacity is probably correlated with their suitable lipophilicity. Specifically, compound 25 showed similar inhibition potency against FAAH in comparison with URB597, one of the most potent FAAH inhibitor known to date.

Conformational Restriction Leading to a Selective CB2 Cannabinoid Receptor Agonist Orally Active Against Colitis

The CB2 cannabinoid receptor has been implicated in the regulation of intestinal inflammation. Following on from the promising activity of a series of 4-oxo-1,4-dihydroquinoline-3-carboxamide, we developed constrained analogues based on a 2H-pyrazolo[4,3-c]quinolin-3(5H)-one scaffold, with improved affinity for the hCB2 receptor and had very high selectivity over the hCB1 receptor. Importantly, the lead of this series (26, hCB2: K i = 0.39 nM, hCB1: K i > 3000 nM) was found to protect mice against experimental colitis after oral administration.

Inhibition of tumor cell growth and angiogenesis by 7-Aminoalkoxy-4-aryloxy-quinazoline ureas, a novel series of multi-tyrosine kinase inhibitors

Several regulatory and signaling molecules governing angiogenesis are targets of interest for the development of drugs in the cancer, including growth factors such as Vascular Endothelial Growth Factor (VEGF) and Platelet-Derived Growth Factor (PDGF). A series of 4-aryloxy-6,7-dimethoxyquinazolines, previously synthesized in our laboratory, has shown a nanomolar inhibition of kinase enzymatic activity of VEGFR, PDGFR and c-Kit. We have therefore studied the impact of the variation in the 7-position substitution of the quinazoline core. Substitution by aminoalkoxy chains led to new highly potent ATP-competitive inhibitors of VEGFR, PDGFR and c-Kit enzyme with IC50 values in the nanomolar range and this substitution has increased greatly antiproliferative activity on cancer cell lines (PC3, MCF7, HT29) and HUVEC (human umbilical vein endothelial cells). One of the most promising compounds (36) was assessed for its ability to limit the induction of web like network of capillary tubes by the human umbilical vascular endothelial cells (HUVEC) and for its ability to inhibit invasion.

Switching cannabinoid response from CB2 agonists to FAAH inhibitors

A series of 3-carboxamido-5-aryl-isoxazoles designed as CB2 agonists were evaluated as FAAH inhibitors. The pharmacological results led to identify structure-activity relationships enabling to switch cannabinoid response from CB2 agonists to FAAH inhibitors. Two compounds were selected for their FAAH and/or CB2 activity, and evaluated in a colitis model for their anti-inflammatory activity. Results showed that compounds 10 and 11 inhibit the development of DSS-induced acute colitis in mice and then, are interesting leads to explore new drug candidates for IBD.

Synthesis and Biological Evaluation of N-[2-(4-Hydroxyphenylamino)-pyridin-3-yl]-4-methoxy-benzenesulfonamide (ABT-751) Tricyclic Analogues as Antimitotic and Antivascular Agents with Potent in Vivo Antitumor Activity

Benzopyridothiadiazepine (2a) and benzopyridooxathiazepine (2b) were modified to produce tricyclic quinazolinone 15-18 or benzothiadiazine 26-27 derivatives. These compounds were evaluated in cytotoxicity and tubulin inhibition assays and led to potent inhibitors of tubulin polymerization. N-[2(4-Methoxyphenyl)ethyl]-1,2-dihydro-pyrimidino[2,1-b]quinazolin-6-one (16a) exhibited the best in vitro cytotoxic activity (GI50 10-66.9 nM) against the NCI 60 human tumor cell line and significant potency against tubulin assembly (IC50 0.812 μM). In mechanism studies, 16a was shown to block cell cycle in G2/M phase and to disrupt microtubule formation and displayed good antivascular properties as inhibition of cell migration, invasion, and endothelial tube formation. Compound 16a was evaluated in C57BL/6 mouse melanoma B16F10 xenograft model to validate its antitumor activity, in comparison with reference ABT-751 (1). Compound 16a displayed strong in vivo antitumor and antivascular activities at a dose of 5 mg/kg without obvious toxicity, whereas 1 needed a 10-fold higher concentration to reach similar effects.

Synthesis and biological evaluation of di-aryl urea derivatives as c-Kit inhibitors

Inhibition of receptor tyrosine kinases (RTKs) continued to be a successful approach for the treatment of many types of human cancers and many potent small molecules kinase inhibitors have been discovered the last decade. In the present study, we describe the synthesis of thienopyrimidine derivatives and their pharmacological evaluation against nine kinases (EGFR, PDGFR-ß, c-Kit, c-Met, Src, Raf, VEGFR-1, -2 and -3). Most of the synthesized compounds showed from moderate to potent activities against c-Kit with IC50 values in the nanomolar range. Among them, 4-anilino(urea)thienopyrimidine analogs showed selectivity and potent c-Kit inhibition with IC50 values less than 6 nM. Docking simulation was performed for the most promising compound 9 into the c-Kit active site to determine the potential binding mode. This study reveal that the 4-anilino(urea)thienopyrimidine is an interesting scaffold to design novel potent and selective c-Kit inhibitors which may make promising candidates for cancers where c-Kit receptors are overexpressed.

New phenylaniline derivatives as modulators of amyloid protein precursor metabolism

The chloroquinoline scaffold is characteristic of anti-malarial drugs such as chloroquine (CQ) or amodiaquine (AQ). These drugs are also described for their potential effectiveness against prion disease, HCV, EBV, Ebola virus, cancer, Parkinson or Alzheimer diseases. Amyloid precursor protein (APP) metabolism is deregulated in Alzheimers disease. Indeed, CQ modifies amyloid precursor protein (APP) metabolism by precluding the release of amyloid-beta peptides (Aβ), which accumulate in the brain of Alzheimer patients to form the so-called amyloid plaques. We showed that AQ and analogs have similar effects although having a higher cytotoxicity. Herein, two new series of compounds were synthesized by replacing 7-chloroquinolin-4-amine moiety of AQ by 2-aminomethylaniline and 2-aminomethylphenyle moieties. Their structure activity relationship was based on their ability to modulate APP metabolism, Aβ release, and their cytotoxicity similarly to CQ. Two compounds 15a, 16a showed interesting and potent effect on the redirection of APP metabolism toward a decrease of Aβ peptide release (in the same range compared to AQ), and a 3-10-fold increased stability of APP carboxy terminal fragments (CTFα and AICD) without obvious cellular toxicity at 100 µM.

Development of novel oxazolo[5,4- d ]pyrimidines as competitive CB 2 neutral antagonists based on scaffold hopping

A series of novel oxazolo[5,4-d]pyrimidines was designed via a scaffold hopping strategy and synthesized through a newly developed approach. All these compounds were evaluated for their biological activity toward CB1/CB2 cannabinoid receptors, their metabolic stability in mice liver microsomes and their cytotoxicity against several cell lines. Eight compounds have been identified as CB2 ligands with Ki values less than 1 μM. It is noteworthy that 2-(2-chlorophenyl)-5-methyl-7-(4-methylpiperazin-1-yl) oxazolo[5,4-d]pyrimidine 47 and 2-(2-chlorophenyl)-7-(4-ethylpiperazin-1-yl)- 5-methyloxazolo[5,4-d]pyrimidine 48 showed CB2 binding affinity in the nanomolar range and significant selectivity over CB1 receptors. Interestingly, functionality studies imply that they behave as competitive neutral antagonists. Moreover, all tested compounds are devoid of cytotoxicity toward several cell lines, including Chinese hamster ovary cells (CHO) and human colorectal adenocarcinoma cells HT29.

Design and synthesis of 2,6-disubstituted-8-amino imidazo[1,2 a ]pyridines, a promising privileged structure

Imidazo[1,2a]pyridines have gained much interest in the field of medicinal chemistry research. In the aim of accessing new privileged structure, we decided to design and synthesize 8-aminated-imidazo[1,2a]pyridines substituted on positions 2 and 6. This scaffold, rarely found in the literature, was obtained via palladium-catalyzed coupling reactions (Suzuki reaction or N-hydroxysuccinimidyl activated ester method) and tested on adenosine receptor A2A. We demonstrated how incorporation of an exocyclic amine enhanced affinity towards this receptor while maintaining low cytotoxicity.