A New Series of Highly Potent Non-Peptide Bradykinin B2 Receptor Antagonists Incorporating the 4-Heteroarylquinoline Framework. Improvement of Aqueous Solubility and New Insights into Species Difference

Development of a multigram synthesis of the bradykinin receptor 2 agonist FR-190997 and analogs thereof

Using Fujisawa's B2R agonist FR-190997, we recently demonstrated for the first time that agonism at the bradykinin receptor type 2 (B2R) produces substantial antiproliferative effects. FR-190997 elicited an EC₅₀ of 80 nM in the triple-negative breast cancer cell line MDA-MB-231, a much superior performance to that exhibited by most approved breast cancer drugs. Consequently, we initiated a program aiming primarily at synthesizing adequate quantities of FR-190997 to support further in vitro and in vivo studies toward its repurposing for various cancers and, in parallel, enable the generation of novel FR-190997 analogs for an SAR study. Prerequisite for this endeavor was to address the synthetic challenges associated with the FR-190997 scaffold, which the Fujisawa chemists had constructed in 20 steps, 13 of which required chromatographic purification. We succeeded in developing a 17-step synthesis amenable to late-stage diversification that eliminated all chromatography and enabled access to multigram quantities of FR-190997 and novel derivatives thereof, supporting further anticancer research based on B2R agonists.

Potent antiproliferative activity of bradykinin B2 receptor selective agonist FR-190997 and analogue structures thereof: A paradox resolved?

Βradykinin stimulation of B2 receptor is known to activate the oncogenic ERK pathway and overexpression of bradykinin receptors B1 and B2 has been reported to occur in glioma, colorectal and cervical cancers. B1R and B2R antagonists have been shown to reverse tumor proliferation and invasion. Paradoxically, B1R and B2R agonism has also been reported to elicit antiproliferative benefits. In order to complement the data accumulated to date with the natural substrate bradykinin and peptidic B2R antagonists, we decided to examine for the first time the response elicited by B2R stimulation in breast cancer lines with a non-peptidic small molecule B2R agonist. We synthesized and assessed the highly selective and potent B2R partial agonist FR-190997 in MCF-7 and MDA-MBA-231 breast cancer lines and found it possessed significant antiproliferative activity (IC₅₀ 2.14 and 0.08 μΜ, respectively). The modular nature of FR-190997 allowed us to conduct a focused SAR study and discover compound 10 which exhibits subnanomolar antiproliferative activity (IC ₅₀ 0.06 nΜ) in the TNBC MDA-MBA-231 cell line. This performance surpasses, in most cases by several orders of magnitude, those of established anticancer agents and FDA-approved breast cancer drugs. In line with the established literature we suggest that this remarkable activity precipitates from a dual mode of action involving agonist-induced receptor internalization/degradation combined with sequestration of functional intracellular B2 receptors and inhibition of the associated endosomal signaling. The latter mode may be realized by appropriate ligands regardless of B2R agonist/antagonist designation which only relates to membrane residing GCPRs. Under this prism the controversy over the antiproliferative effects of B2 agonists and antagonists is potentially neutralized.

Cinnamamide: An insight into the pharmacological advances and structure-activity relationships

The cinnamamide (cinnamic acid amide and cinnamide) is a privileged scaffold present widely in a number of natural products. The scaffold acts as a useful template for designing and arriving at newly drug-like molecules with potential pharmacological activity. An attempt has been made to review the extensive occurrence of cinnamamide scaffold in many lead compounds reported for treating various diseases, their binding interactions with the therapeutic targets as well as mechanism of action and their structure-activity relationships. The discoveries of cinnamamide systems and some examples of unusual cinnamamides having an aromatic, aliphatic, and heterocyclic or other rings condensed to the basic cinnamamide structure also have been extensively covered in this review.

Solvent-free and room temperature synthesis of 3-arylquinolines from different anilines and styrene oxide in the presence of Al2O3/MeSO3H

A highly efficient, simple and environmentally friendly synthesis of 3-arylquinolines has been developed in the presence of Al₂O₃/MeSO₃H via one-pot reaction of anilines and styrene oxide. This methodology provides very rapid access to 3-arylquinolines in good to excellent yields under solvent-free conditions at room temperature in air.

Synthesis of 4-substituted 3-(2-hydroxyphenyl)-quinolines through an unexpected iron(iii) chloride promoted reaction of cyclic imine dibenzo[b,f][1,4]oxazepines with alkynes

An unexpected FeCl₃-promoted reaction of cyclic imine dibenzo[b,f][1,4]oxazepines with alkynes was studied to produce novel 4-substituted 3-(2-hydroxyphenyl)-quinolines with 34–88% yield.

Pd-Catalyzed Ligand-Free Synthesis of Arylated Heteroaromatics by Coupling of N-Heteroaromatic Bromides with Iodobenzene Diacetate, Iodosobenzene, or Diphenyliodonium Salts

An efficient method for synthesizing arylated heteroaromatics has been reported via Pd-catalyzed ligand-free cross-coupling of N-heteroaromatic bromides with iodine(III) reagents under mild conditions. Iodobenzene diacetate, iodosobenzene, and diphenyliodonium salts act as ideal arylated sources in this reaction, producing bioactive aromatic-substituted pyridines and quinolines in moderate to high yields.

Novel small molecule bradykinin B2 receptor antagonists

Blockade of the bradykinin B(2) receptor provides therapeutic benefit in hereditary angioedema (HAE) and potentially in many other diseases. Herein, we describe the development of highly potent B(2) receptor antagonists with a molecular weight of approximately 500 g/mol. First, known quinoline-based B(2) receptor antagonists were stripped down to their shared core motif 53, which turned out to be the minimum pharmacophore. Targeted modifications of 53 resulted in the highly water-soluble lead compound 8a. Extensive exploration of its structure-activity relationship resulted in a series of highly potent B(2) receptor antagonists, featuring a hydrogen bond accepting functionality, which presumably interacts with the side chain of Asn-107 of the B(2) receptor. Optimization of the microsomal stability and cytochrome P450 inhibition eventually led to the discovery of the highly potent and orally available B(2) receptor antagonist 52e (JSM10292), which showed the best overall properties.

Nickel-catalyzed cyclization of 2-iodoanilines with aroylalkynes: an efficient route for quinoline derivatives

An efficient and convenient nickel-catalyzed cyclization of 2-iodoanilines with alkynyl aryl ketones to give 2,4-disubstituted quinolines was developed. The reaction can be employed for the synthesis of naturally occurring quinoline derivatives in good yields. On the basis of the regiochemistry of the products, the possible pathway for the reaction is via the formation of o-aminochalcone.