Potent, orally active heterocycle-based combretastatin A-4 analogues: synthesis, structure-activity relationship, pharmacokinetics, and in vivo antitumor activity evaluation

I2-catalyzed synthesis of substituted imidazoles from vinyl azides and benzylamines

A novel and efficient I₂-catalyzed oxidative tandem cyclization of simple vinyl azides and benzylamines has been developed for the synthesis of substituted imidazoles.

Perlite: an inexpensive natural support for heterogenization of HBF4

Nano-perlite-fluoroboric acid (n-PeFBA) has been synthesized by immobilization of HBF₄ on perlite as a natural and cheap support to produce an efficient green heterogeneous reusable solid acid catalyst.

Synthesis and optical properties of phenanthromidazole derivatives for organic electroluminescent devices

The external quantum efficiency roll-off may be due to triplet–triplet annihilation (TTA) and triplet–polaron annihilation (TPA).

Synthesis of 2-anilinopyridine–arylpropenone conjugates as tubulin inhibitors and apoptotic inducers

2-Anilinopyridine–arylpropenone conjugates as novel tubulin inhibitors and apoptotic inducers.

Formation mechanisms and yields of small imidazoles from reactions of glyoxal with NH4+ in water at neutral pH

Yields of imidazoles produced by the reactions of glyoxal with NH₄⁺.

Multi-component synthesis of highly substituted imidazoles catalyzed by nanorod vanadatesulfuric acid

Nanorod vanadatesulfuric acid (VSA NRs), as a recyclable and eco-benign catalyst, was used for one-pot synthesis of 2,4,5-trisubstituted imidazoles and 1,2,4,5-tetrasubstituted imidazoles using aldehydes, benzil, benzoin or 9,10-phenanthrenequinone and ammonium acetate or aniline under solvent-free conditions providing high to excellent yields. VSA is easily prepared by a simple reaction of chlorosulfonic acid and sodium metavanadate in high purity. As compared with the conventional procedures, the present protocol offers several advantages such as simplicity of procedure, short reaction time, high yields, easy workup, recoverability and reusability of the catalyst and simple purification of the products.

Synthesis, cytotoxicity, docking study, and tubulin polymerization inhibitory activity of novel 1-(3,4-dimethoxyphenyl)-5-(3,4,5-trimethoxyphenyl)-1H-1,2,4-triazole-3-carboxanilides

A series of novel 1-(3,4-methoxyphenyl)-5-(3,4,5-trimethoxyphenyl)-1H-1,2,4-triazole-3-carboxylic acid derivatives (4a-n) were synthesized and evaluated for their in vitro cytotoxic activity against the growth of four different human cell lines (hepatocarcinoma HepG2, breast adenocarcinoma MCF-7, colon carcinoma DLD-1, and leukemia HL-60). The anilides of m-anisidine 4e, o-anisidine 4f, and 3,5-difluoroaniline 4l demonstrated best results on MCF-7 cells and mean IC50 values of 7.79, 10.79, and 13.20 µM, respectively. The compounds produced a significant reduction in cellular microtubules at a concentration of 25 µg/mL, for microtubule loss. Molecular modeling studies involving compounds 4d, 4e, 4f, and 4l with the colchicine binding site of α,β-tubulin revealed hydrogen bonding and hydrophobic interactions with several amino acids in the colchicine binding site of β-tubulin.

Gold(I) biscarbene complexes derived from vascular-disrupting combretastatin A-4 address different targets and show antimetastatic potential

Gold N-heterocyclic carbene (NHC) complexes are an emerging class of anticancer drugs. We present a series of gold(I) biscarbene complexes with NHC ligands derived from the plant metabolite combretastatin A-4 (CA-4) that retain its vascular-disrupting effect, yet address different cellular and protein targets. Unlike CA-4, these complexes did not interfere with tubulin, but with the actin cytoskeleton of endothelial and cancer cells. For the highly metastatic 518A2 melanoma cell line this effect was accompanied by a marked accumulation of cells in the G1 phase of the cell cycle and a suppression of active prometastatic matrix metalloproteinase-2. Despite these mechanistic differences the complexes were as strongly antivascular as CA-4 both in vitro in tube formation assays with human umbilical vein endothelial cells, and in vivo as to blood vessel disruption in the chorioallantoic membrane of chicken eggs. The antiproliferative effect of the new gold biscarbene complexes in a panel of six human cancer cell lines was impressive, with low sub-micromolar IC50 values (72 h) even against CA-4-refractory HT-29 colon and multidrug-resistant MCF-7 breast carcinoma cells. In preliminary studies with a mouse melanoma xenograft model the complexes led to significant decreases in tumor volume while being very well tolerated.

Effects of the tumor-vasculature-disrupting agent verubulin and two heteroaryl analogues on cancer cells, endothelial cells, and blood vessels

Two analogues of the discontinued tumor vascular-disrupting agent verubulin (Azixa®, MPC-6827, 1) featuring benzo-1,4-dioxan-6-yl (compound 5 a) and N-methylindol-5-yl (compound 10) residues instead of the para-anisyl group on the 4-(methylamino)-2-methylquinazoline pharmacophore, were prepared and found to exceed the antitumor efficacy of the lead compound. They were antiproliferative with single-digit nanomolar IC50 values against a panel of nine tumor cell lines, while not affecting nonmalignant fibroblasts. Indole 10 surpassed verubulin in seven tumor cell lines including colon, breast, ovarian, and germ cell cancer cell lines. In line with docking studies indicating that compound 10 may bind the colchicine binding site of tubulin more tightly (Ebind =-9.8 kcal mol(-1) ) than verubulin (Ebind =-8.3 kcal mol(-1) ), 10 suppressed the formation of vessel-like tubes in endothelial cells and destroyed the blood vessels in the chorioallantoic membrane of fertilized chicken eggs at nanomolar concentrations. When applied to nude mice bearing a highly vascularized 1411HP germ cell xenograft tumor, compound 10 displayed pronounced vascular-disrupting effects that led to hemorrhages and extensive central necrosis in the tumor.

Combretastatin A-4 inspired novel 2-aryl-3-arylamino-imidazo-pyridines/pyrazines as tubulin polymerization inhibitors, antimitotic and anticancer agents

Novel 2-aryl-3-arylamino-imidazo-pyridines/pyrazines that exhibit potent tubulin polymerization inhibition, anticancer activity, anti-migration of cancer cells, chromosomal damage, and apoptosis have been developed.

Nano rutile TiO2 catalysed synthesis of (E)-4-(2-(1-(4-chlorophenyl)-1H-phenanthro[9,10-d]imidazol-2-yl)vinyl)-N,N-dimethylaniline and its interaction with super paramagnetic nanoparticles

The synthesis of (E)-4-(2-(1-(4-chlorophenyl)-1H-phenanthro[9,10-d]imidazol-2-yl)vinyl)-N,N-dimethylaniline (CPPIVI) has been carried out using TiO₂ (R) as catalyst under solvent free conditions and characterized by NMR spectral studies.

Synthesis and evaluation of a series of quinolinyl trans-cyanostilbene analogs as anticancer agents

2-Quinolyl- and 3-quinolyl-cyanocombretastatin analogs exhibit potent growth inhibition against a panel of 60 human cancer cell lines.

Ion-based materials derived from positively and negatively charged chloride complexes of π-conjugated molecules

Oriented salts from planar charged species were prepared by combining positively and negatively charged receptor-anion complexes with similar geometries using dicationic and electronically neutral π-conjugated receptors. Phenylene- or pyrimidine-bridged bis(imidazolium) dicationic anion receptors formed monocationic receptor-Cl(-) complexes that were accompanied by a free Cl(-). This free Cl(-) was subsequently captured by pyrrole-based neutral anion receptors to form negatively charged receptor-Cl(-) complexes. The ion pair of the resulting positively and negatively charged planar receptor-Cl(-) complexes could produce a supramolecular octane gel, adopting a lamellar self-organized structure in its xerogel state. On the other hand, the solid-state ion pairs had hexagonal columnar mesophases, which formed via alternate stacking of the positively and negatively charged planar receptor-Cl(-) complexes. By use of the flash-photolysis time-resolved microwave conductivity technique, the one-dimensional charge-carrier transporting property, with a mobility of 0.05 cm(2) V(-1) s(-1), was determined for the newly prepared solid-state ion pairs.

Tubulin-interactive stilbene derivatives as anticancer agents

Microtubules are dynamic polymers that occur in eukaryotic cells and play important roles in cell division, motility, transport and signaling. They form during the process of polymerization of α- and β-tubulin dimers. Tubulin is a significant and heavily researched molecular target for anticancer drugs. Combretastatins are natural cis-stilbenes that exhibit cytotoxic properties in cultured cancer cells in vitro. Combretastatin A-4 (3′-hydroxy-3,4,4′, 5-tetramethoxy-cis-stilbene; CA-4) is a potent cytotoxic cis-stilbene that binds to β-tubulin at the colchicine-binding site and inhibits tubulin polymerization. The prodrug CA-4 phosphate is currently in clinical trials as a chemotherapeutic agent for cancer treatment. Numerous series of stilbene analogs have been studied in search of potent cytotoxic agents with the requisite tubulin-interactive properties. Microtubule-interfering agents include numerous CA-4 and transresveratrol analogs and other synthetic stilbene derivatives. Importantly, these agents are active in both tumor cells and immature endothelial cells of tumor blood vessels, where they inhibit the process of angiogenesis. Recently, computer-aided virtual screening was used to select potent tubulin-interactive compounds. This review covers the role of stilbene derivatives as a class of antitumor agents that act by targeting microtubule assembly dynamics. Additionally, we present the results of molecular modeling of their binding to specific sites on the α- and β-tubulin heterodimer. This has enabled the elucidation of the mechanism of stilbene cytotoxicity and is useful in the design of novel agents with improved anti-mitotic activity. Tubulin-interactive agents are believed to have the potential to play a significant role in the fight against cancer.

One-pot Synthesis of Polysubstituted Imidazoles in a Brønsted Acidic Deep Eutectic Solvent

A Brønsted acidic deep eutectic solvent based on choline chloride and p-toluenesulfonic acid was prepared and was found to be effective for the one-pot synthesis of 2,4,5-trisubstituted and 1,2,4,5-tetrasubstituted imidazoles with high yields. In addition, the deep eutectic solvent is non-toxic, cost-effective and recyclable.

TR-644 a novel potent tubulin binding agent induces impairment of endothelial cells function and inhibits angiogenesis

TR-644 is a novel combretastatin A-4 (CA-4) analogue endowed with potent microtubule depolymerizing activity superior to that of the lead compound and it also has high affinity to colchicines binding site of tubulin. We tested TR-644 anti-angiogenic effects in human umbilical endothelial cells (HUVEC). It showed no significant effects on the growth of HUVEC cells at concentrations below 1,000 nM, but at much lower concentrations (10-100 nM) it induced inhibition of capillary tube formation, inhibition of endothelial cell migration and affected endothelial cell morphology as demonstrated by the disruption of the microtubule network. TR-644 also increased permeability of HUVEC cells in a time dependent manner. The molecular mechanism for the anti-vascular activity of TR-644 was investigated in detail. TR-644 caused G2/M arrest in endothelial cells and this effect correlated with downregulation of the expression of Cdc25C and Cdc2(Tyr15). Moreover TR-644 inhibited VEGF-induced phosphorylation of VE-cadherin but did not prevent the VEGF-induced phosphorylation of FAK. In chick chorioallantoic membrane in vivo assay, TR-644 (0.1-1.0 pmol/egg) efficiently counteracted the strong angiogenic response induced by FGF. Also CA-4, used as reference compound, caused an antagonistic effect, but in contrast, it induced per se, a remarkable angiogenic response probably due to an inflammatory reaction in the site of treatment. In a mice allogenic tumor model, immunohistochemical staining of tumors with anti-CD31 antibody showed that TR-644 significantly reduced the number of vessel, after 24 h from the administration of a single dose (30 mg/Kg).

Application of Suzuki arylation, Sonogashira ethynylation and Rosenmund-von Braun cyanation in the exploration of substitution effects on the anticancer activity of 2-aroylquinolines

A variety of functionalities were introduced at 2-aroylquinoline's C5 position, which is considered equivalent to C-3' of the B-ring of CA4, via Suzuki arylation, Sonogashira ethynylation, and Rosenmund-von Braun cyanation. These substitutions are rarely utilized in the modification of 3'-OH of CA4. The resulting products 6 and 7 having cyano and ethynyl groups exhibited comparable antiproliferative and tubulin inhibitory activities to colchicine.

Sonochemical synthesis of 1,2,4,5-tetrasubstituted imidazoles using nanocrystalline MgAl2O4 as an effective catalyst

An efficient four-component synthesis of 1,2,4,5-tetrasubstituted imidazoles is described by one-step condensation of an aldehyde, benzil, ammonium acetate and primary aromatic amine with nanocrystalline magnesium aluminate in ethanol under ultrasonic irradiation. High yields, short reaction times, mild conditions, simplicity of operation and easy work-up are some advantages of this protocol.