Organoruthenium Antagonists of Human A3Adenosine Receptors

Ruthenium(ii) p-cymene complexes of pyridine-2-carboxaldehyde and 2-amino benzothiazole-based ligands: cytoselective and in vitro live cell imaging agents

A new class of DNA targeting, highly cytoselective, luminescent Ru(ii)–arene complexes was developed.

Discovery of benzothiazolylquinoline conjugates as novel human A3 receptor antagonists: biological evaluations and molecular docking studies

Adenosine is known as an endogenous purine nucleoside and it modulates a wide variety of physiological responses by interacting with adenosine receptors. Among the four adenosine receptor subtypes, the A3 receptor is of major interest in this study as it is overexpressed in some cancer cell lines. Herein, we have highlighted the strategy of designing the hA3 receptor targeted novel benzothiazolylquinoline scaffolds. The radioligand binding data of the reported compounds are rationalized with the molecular docking results. Compound 6a showed best potency and selectivity at hA3 among other adenosine receptors.

Amberlite IR-120(H)-mediated “on water” synthesis of novel anticancer ruthenium(ii)–p-cymene 2-pyridinylbenzothiazole (BTZ), 2-pyridinylbenzoxazole (BOZ) & 2-pyridinylbenzimidazole (BIZ) scaffolds

A class of novel Ru(ii)–p-cymene BTZ, BOZ & BIZ complexes have been synthesized “on water” using Amberlite IR-120(H) resin and their anticancer activities were evaluated.

In vivo phenotypic screening for treating chronic neuropathic pain: modification of C2-arylethynyl group of conformationally constrained A3 adenosine receptor agonists

(N)-Methanocarba adenosine 5'-methyluronamides containing 2-arylethynyl groups were synthesized as A3 adenosine receptor (AR) agonists and screened in vivo (po) for reduction of neuropathic pain. A small N(6)-methyl group maintained binding affinity, with human > mouse A3AR and MW < 500 and other favorable physicochemical properties. Emax (maximal efficacy in a mouse chronic constriction injury pain model) of previously characterized A3AR agonist, 2-(3,4-difluorophenylethynyl)-N(6)-(3-chlorobenzyl) derivative 6a, MRS5698, was surpassed. More efficacious analogues (in vivo) contained the following C2-arylethynyl groups: pyrazin-2-yl 23 (binding Ki, hA3AR, nM 1.8), fur-2-yl 27 (0.6), thien-2-yl 32 (0.6) and its 5-chloro 33, MRS5980 (0.7) and 5-bromo 34 (0.4) equivalents, and physiologically unstable ferrocene 36, MRS5979 (2.7). 33 and 36 displayed particularly long in vivo duration (>3 h). Selected analogues were docked to an A3AR homology model to explore the environment of receptor-bound C2 and N(6) groups. Various analogues bound with μM affinity at off-target biogenic amine (M2, 5HT2A, β3, 5HT2B, 5HT2C, and α2C) or other receptors. Thus, we have expanded the structural range of orally active A3AR agonists for chronic pain treatment.

Discovery and investigation of anticancer ruthenium-arene Schiff-base complexes via water-promoted combinatorial three-component assembly

The structural diversity of metal scaffolds makes them a viable alternative to traditional organic scaffolds for drug design. Combinatorial chemistry and multicomponent reactions, coupled with high-throughput screening, are useful techniques in drug discovery, but they are rarely used in metal-based drug design. We report the optimization and validation of a new combinatorial, metal-based, three-component assembly reaction for the synthesis of a library of 442 Ru-arene Schiff-base (RAS) complexes. These RAS complexes were synthesized in a one-pot, on-a-plate format using commercially available starting materials under aqueous conditions. The library was screened for their anticancer activity, and several cytotoxic lead compounds were identified. In particular, [(η6-1,3,5-triisopropylbenzene)RuCl(4-methoxy-N-(2-quinolinylmethylene)aniline)]Cl (4) displayed low micromolar IC50 values in ovarian cancers (A2780, A2780cisR), breast cancer (MCF7), and colorectal cancer (HCT116, SW480). The absence of p53 activation or changes in IC50 value between p53+/+ and p53-/- cells suggests that 4 and possibly the other lead compounds may act independently of the p53 tumor suppressor gene frequently mutated in cancer.

Metal complexes as structural templates for targeting proteins

This article reviews recent advances in the design and discovery of inert metal complexes as protein binders. In these metal-based probes or drug candidates, the metal is supposed to exert a purely structural role by organizing the coordinating ligands in the three dimensional space to achieve a shape and functional group complementarity with the targeted protein pockets. Presented examples of sandwich, half-sandwich and octahedral d(6)-metal complexes reinforce previous perceptions that metal complexes are highly promising scaffolds for the design of small-molecule protein binders and complement the molecular diversity of organic chemistry by opening untapped chemical space.

Mirror-image organometallic osmium arene iminopyridine halido complexes exhibit similar potent anticancer activity

Four chiral Os(II) arene anticancer complexes have been isolated by fractional crystallization. The two iodido complexes, (S(Os),S(C))-[Os(η(6)-p-cym)(ImpyMe)I]PF6 (complex 2, (S)-ImpyMe: N-(2-pyridylmethylene)-(S)-1-phenylethylamine) and (R(Os),R(C))-[Os(η(6)-p-cym)(ImpyMe)I]PF6 (complex 4, (R)-ImpyMe: N-(2-pyridylmethylene)-(R)-1-phenylethylamine), showed higher anticancer activity (lower IC50 values) towards A2780 human ovarian cancer cells than cisplatin and were more active than the two chlorido derivatives, (S(Os),S(C))-[Os(η(6)-p-cym)(ImpyMe)Cl]PF6, 1, and (R(Os),R(C))-[Os(η(6)-p-cym)(ImpyMe)Cl]PF6, 3. The two iodido complexes were evaluated in the National Cancer Institute 60-cell-line screen, by using the COMPARE algorithm. This showed that the two potent iodido complexes, 2 (NSC: D-758116/1) and 4 (NSC: D-758118/1), share surprisingly similar cancer cell selectivity patterns with the anti-microtubule drug, vinblastine sulfate. However, no direct effect on tubulin polymerization was found for 2 and 4, an observation that appears to indicate a novel mechanism of action. In addition, complexes 2 and 4 demonstrated potential as transfer-hydrogenation catalysts for imine reduction.