Comparison of zafirlukast (Accolate) absorption after oral and colonic administration in humans

Cascade Synthesis of New Indole-Containing Pentacyclic Scaffolds Mediated by Aryl and Iminyl Radicals

A five-step approach, starting from simple 1,5-disubstituted indoles, has been implemented for the synthesis of diversely substituted indole-pyrido-indene pentacyclic compounds up to 54 % yield via domino radical-mediated processes in the presence of the radical reagents DLP/TTMSS and AIBN/TTMSS. Reactions proceeded with diverse key starting radical cyano-precursors strategically synthesized which were subsequently transformed into the target pentacyclic compounds through an aryl/iminyl radical-mediated domino reactions sequence. In addition to the routine spectroscopic techniques, the structure of radical precursors, as well as, the target pentacyclic products were unequivocally established by single crystal X-ray diffraction, confirming the effectiveness of the proposed synthetic sequence.

Targeting thiol isomerase activity with zafirlukast to treat ovarian cancer from the bench to clinic

Thiol isomerases, including PDI, ERp57, ERp5, and ERp72, play important and distinct roles in cancer progression, cancer cell signaling, and metastasis. We recently discovered that zafirlukast, an FDA-approved medication for asthma, is a pan-thiol isomerase inhibitor. Zafirlukast inhibited the growth of multiple cancer cell lines with an IC50 in the low micromolar range, while also inhibiting cellular thiol isomerase activity, EGFR activation, and downstream phosphorylation of Gab1. Zafirlukast also blocked the procoagulant activity of OVCAR8 cells by inhibiting tissue factor-dependent Factor Xa generation. In an ovarian cancer xenograft model, statistically significant differences in tumor size between control vs treated groups were observed by Day 18. Zafirlukast also significantly reduced the number and size of metastatic tumors found within the lungs of the mock-treated controls. When added to a chemotherapeutic regimen, zafirlukast significantly reduced growth, by 38% compared with the mice receiving only the chemotherapeutic treatment, and by 83% over untreated controls. Finally, we conducted a pilot clinical trial in women with tumor marker-only (CA-125) relapsed ovarian cancer, where the rate of rise of CA-125 was significantly reduced following treatment with zafirlukast, while no severe adverse events were reported. Thiol isomerase inhibition with zafirlukast represents a novel, well-tolerated therapeutic in the treatment of ovarian cancer.

ATP-releasing SWELL1 channel in spinal microglia contributes to neuropathic pain

Following peripheral nerve injury, extracellular adenosine 5'-triphosphate (ATP)-mediated purinergic signaling is crucial for spinal cord microglia activation and neuropathic pain. However, the mechanisms of ATP release remain poorly understood. Here, we show that volume-regulated anion channel (VRAC) is an ATP-releasing channel and is activated by inflammatory mediator sphingosine-1-phosphate (S1P) in microglia. Mice with microglia-specific deletion of Swell1 (also known as Lrrc8a), a VRAC essential subunit, had reduced peripheral nerve injury-induced increase in extracellular ATP in spinal cord. The mutant mice also exhibited decreased spinal microgliosis, dorsal horn neuronal hyperactivity, and both evoked and spontaneous neuropathic pain-like behaviors. We further performed high-throughput screens and identified an FDA-approved drug dicumarol as a novel and potent VRAC inhibitor. Intrathecal administration of dicumarol alleviated nerve injury-induced mechanical allodynia in mice. Our findings suggest that ATP-releasing VRAC in microglia is a key spinal cord determinant of neuropathic pain and a potential therapeutic target for this debilitating disease.

ATP-releasing SWELL1 channel in spinal microglia contributes to neuropathic pain

Following peripheral nerve injury, extracellular ATP-mediated purinergic signaling is crucial for spinal cord microglia activation and neuropathic pain. However, the mechanisms of ATP release remain poorly understood. Here, we show that volume-regulated anion channel (VRAC) is an ATP-releasing channel and is activated by inflammatory mediator sphingosine-1-phosphate (S1P) in microglia. Mice with microglia-specific deletion of Swell1 (also known as Lrrc8a), a VRAC essential subunit, had reduced peripheral nerve injury-induced increase in extracellular ATP in spinal cord. The mutant mice also exhibited decreased spinal microgliosis, dorsal horn neuronal hyperactivity, and both evoked and spontaneous neuropathic pain-like behaviors. We further performed high-throughput screens and identified an FDA-approved drug dicumarol as a novel and potent VRAC inhibitor. Intrathecal administration of dicumarol alleviated nerve injury-induced mechanical allodynia in mice. Our findings suggest that ATP-releasing VRAC in microglia is a key spinal cord determinant of neuropathic pain and a potential therapeutic target for this debilitating disease.

Zafirlukast is a broad-spectrum thiol isomerase inhibitor that inhibits thrombosis without altering bleeding times

BACKGROUND AND PURPOSE

Multiple members of the thiol isomerase (TI) family of enzymes are present in and released by platelets. Inhibition of these enzymes results in diminished platelet responses, aggregation, adhesion and thrombus formation. Recently, the therapeutic potential of TI inhibition has been recognised and drug-development technologies were used to identify selective small molecule inhibitors. To date, few pan-TI inhibitors have been characterised and the most studied, bacitracin, is known to be nephrotoxic, which prohibits its systemic therapeutic usage.

EXPERIMENTAL APPROACH

We therefore sought to identify novel broad-spectrum inhibitors of these enzymes and test their effects in vivo. A total of 3,641 compounds were screened for inhibitory effects on the redox activity of ERp5, protein disulphide isomerase (PDI), ERp57, ERp72 and thioredoxin in an insulin turbidity assay. Of the lead compounds identified, zafirlukast was selected for further investigation.

KEY RESULTS

When applied to platelets, zafirlukast diminished platelet responses in vitro. Zafirlukast was antithrombotic in murine models of thrombosis but did not impair responses in a model of haemostasis. Since TIs are known to modulate adhesion receptor function, we explored the effects of zafirlukast on cell migration. This was inhibited independently of cysteinyl LT receptor expression and was associated with modulation of cell-surface free thiol levels consistent with alterations in redox activity on the cell surface.

CONCLUSION AND IMPLICATIONS

We identify zafirlukast to be a novel, potent, broad-spectrum TI inhibitor, with wide-ranging effects on platelet function, thrombosis and integrin-mediated cell migration. Zafirlukast is antithrombotic but does not cause bleeding.

Recent Advances in Iodine-Promoted C-S/N-S Bonds Formation

Sulfur-containing scaffold, as a ubiquitous structural motif, has been frequently used in natural products, bioactive chemicals and pharmaceuticals, particularly C-S/N-S bonds are indispensable in many biological important compounds and pharmaceuticals. Development of mild and general methods for C-S/N-S bonds formation has great significance in modern research. Iodine and its derivatives have been recognized as inexpensive, environmentally benign and easy-handled catalysts or reagents to promote the construction of C-S/N-S bonds under mild reaction conditions, with good regioselectivities and broad substrate scope. Especially based on this, several new strategies, such as oxidation relay strategy, have been greatly developed and accelerated the advancement of this field. This review focuses on recent advances in iodine and its derivatives promoted hybridized C-S/N-S bonds formation. The features and mechanisms of corresponding reactions are summarized and the results of some cases are compared with those of previous reports. In addition, the future of this domain is discussed.

Synthesis ofN-sulfenyl-sulfoximines and -sulfenamides through a metal-free N–H/S–H dehydrocoupling reaction

A metal-free, iodine-catalyzed N–H/S–H dehydrocoupling reaction of sulfoximines and anilines with various thiols to construct sulfur–nitrogen bonds has been developed.

Hyperalgesic and edematogenic effects of Secapin-2, a peptide isolated from Africanized honeybee (Apis mellifera) venom

Honeybee stings are a severe public health problem. Bee venom contains a series of active components, including enzymes, peptides, and biogenic amines. The local reactions observed after envenoming include a typical inflammatory response and pain. Honeybee venom contains some well-known polycationic peptides, such as Melittin, Apamin, MCD peptide, Cardiopep, and Tertiapin. Secapin in honeybee venom was described 38 years ago, yet almost nothing is known about its action. A novel, variant form of this peptide was isolated from the venom of Africanized honeybees (Apis mellifera). This novel peptide, named Secapin-2, is 25 amino acid residues long. Conformational analyses using circular dichroism and molecular dynamics simulations revealed a secondary structure rich in strands and turns, stabilized by an intramolecular disulfide bridge. Biological assays indicated that Secapin-2 did not induce hemolysis, mast cell degranulation or chemotactic activities. However, Secapin-2 caused potent dose-related hyperalgesic and edematogenic responses in experimental animals. To evaluate the roles of prostanoids and lipid mediators in the hyperalgesia and edema induced by this peptide, Indomethacin and Zileuton were used to inhibit the cyclooxygenase and lipoxygenase pathways, respectively. The results showed that Zileuton partially blocked the hyperalgesia induced by Secapin-2 and decreased the edematogenic response. In contrast, Indomethacin did not interfere with these phenomena. Zafirlukast, a leukotriene receptor antagonist, blocked the Secapin-2 induced hyperalgesia and edematogenic response. These results indicate that Secapin-2 induces inflammation and pain through the lipoxygenase pathway in both phenomena.

A simple one-pot 2-step N-1-alkylation of indoles with α-iminoketones toward the expeditious 3-step synthesis of N-1-quinoxaline-indoles

A straightforward procedure for the preparation of N-quinoxaline-indoles is presented. A base-catalyzed one-pot addition of indoles to a preformed α-iminoketone proceeds on the N-1 indole and the subsequent adduct undergoes an acid-mediated deprotection of an internal amino nucleophile, intramolecular cyclization and final oxidation generating N-1-quinoxaline-indoles in good yield.

Synthesis, Antimicrobial, and Antioxidant Activities of N-[(5′-Substituted-2′-phenyl-1H-indol-3′-yl)methylene]-5H-dibenzo[b,f]azepine-5-carbohydrazide Derivatives

The main aim of the present study was to synthesize new leads with potential antimicrobial and antioxidant activities. As a part of systematic investigation of synthesis and biological activity, some new indole compounds3a–cand4a–cwere prepared and screened for their antimicrobial and antioxidant activities. The antimicrobial evaluation of newly synthesized compounds was carried out by cup-plate method. Antimicrobial activity results revealed that compound4ashowed promising activity against bacteriaStaphylococcus aureus,Klebsiella pneumonia, andPseudomonas aeruginosaand exhibited maximum inhibition againstAspergillus niger,Aspergillus oryzae,Aspergillus terreus, andAspergillus flavus. The antioxidant activity was performed by three methods, namely, radical scavenging activity (RSA), ferric ions (Fe+3) reducing antioxidant power (FRAP), and metal chelating activity by using Hatano’s, Oyaizu’s, and Dinis' methods, respectively. Compound4ashowed promising RSA, FRAP, and metal chelating activity.

Toward an increased understanding of the barriers to colonic drug absorption in humans: implications for early controlled release candidate assessment

The purpose of this study was to increase the understanding of in vivo colonic drug absorption in humans by summarizing and evaluating all regional in vivo human absorption data with focus on the interpretation of the colonic absorption data in relation to intestinal permeability and solubility. In addition, the usefulness of the Biopharmaceutics Classification System (BCS) in early assessment of the in vivo colonic absorption potential of controlled release drug candidates was investigated. Clinical regional absorption data (Cmax, Tmax, and AUC) of 42 drugs were collected from journal articles, abstracts, and internal reports, and the relative bioavailability in the colon (Frel(colon)) was obtained directly or calculated. Bioavailability, fraction dose absorbed, and information if the compounds were substrates for P-glycoprotein (P-gp) or cytochrome P450 3A (CYP3A) were also obtained. The BCS I drugs were well absorbed in the colon (Frel(colon) > 70%), although some drugs had lower values due to bacterial degradation in the colon. The low permeability drugs (BCS III/IV) had a lower degree of absorption in the colon (Frel(colon) < 50%). There was a clear correlation between in vitro Caco-2 permeability and Frel(colon), and atenolol and metoprolol may function as permeability markers for low and high colonic absorption, respectively. No obvious effect of P-gp on the colonic absorption of the drugs in this study was detected. There was insufficient data available to fully assess the impact of low solubility and slow dissolution rate. The estimated in vivo fractions dissolved of the only two compounds administered to the colon as both a solution and as solid particles were 55% and 92%, respectively. In conclusion, permeability and solubility are important barriers to colonic absorption in humans, and in vitro testing of these properties is recommended in early assessment of colonic absorption potential.

Determination of zafirlukast by stability indicating LC and derivative spectrophotometry

Two analytical methods have been developed for the determination of zafirlukast, a novel anti-asthmatic drug: high performance liquid chromatography (HPLC) and derivative spectrophotometry (DS). HPLC with ultraviolet detection at 225 nm is carried out with a Symmetry Shield RP18 column and a mobile phase constituted of acetonitrile and 0.01 M potassium dihydrogen phosphate buffer, adjusted the pH to 3.5 with 0.1 M KOH. The LC method is simple, rapid, selective and stability indicating. Indole was used as internal standard for the purpose of quantification of zafirlukast in HPLC. Spectrophotometry uses the third order derivative of the UV spectrum at 251.1 nm (deltalambda value 2.1 nm) for determination. Both methods were fully validated and a comparison was made. The results confirm that the methods are highly suitable for its intended purpose.

Pharmacokinetic profile of zafirlukast

Zafirlukast is a cysteinyl leukotriene type 1 receptor antagonist that causes bronchodilation and has anti-inflammatory properties. Clinical efficacy has been demonstrated when using oral doses of 20 to 40 mg twice daily. The pharmacokinetics of zafirlukast are best described by a two-compartment model. Maximum plasma concentrations (Cmax) were achieved 3 hours after a single oral dose of 20 or 40 mg to healthy volunteers. The absolute bioavailability of zafirlukast is unknown. However, coadministration of zafirlukast with food reduces bioavailability by approximately 40%. The drug binds to plasma proteins (>99%), predominantly to albumin, and has a mean terminal elimination half-life of approximately 10 hours in both healthy volunteers and patients with asthma. Zafirlukast undergoes extensive hepatic metabolism. Hydroxylation by cytochrome P450 (CYP) 2C9 is the major biotransformation pathway. The metabolites of zafirlukast contribute little to its overall activity. Zafirlukast is mainly eliminated in the faeces, while urinary excretion accounts for <10% of an orally administered dose. Because of its primarily hepatic metabolism, the clearance of zafirlukast is reduced in patients with hepatic impairment. In patients with stable alcoholic cirrhosis, Cmax and area under the plasma concentration-time curve for zafirlukast were increased by 50 to 60% compared with healthy volunteers. Asymptomatic elevations of serum liver enzymes have been reported with high dosages of zafirlukast (80 mg twice daily), returning to normal after cessation of the drug. Inhibition of the CYP2C9 and CYP3A isoenzymes by zafirlukast has been reported in vitro. Zafirlukast interacts with warfarin and produces a clinically significant increase in the prothrombin time, but it does not alter the pharmacokinetics of terfenadine carboxylate, the active metabolite of terfenadine. Plasma concentrations of zafirlukast decreased when the drug was administered concomitantly with erythromycin, terfenadine or theophylline, and increased when it was coadministered with aspirin (acetylsalicylic acid). Theophylline metabolism is unchanged in most cases by zafirlukast, but there is a report of one patient with increased theophylline plasma concentrations when zafirlukast was coadministered. Recently, cases of Churg-Strauss syndrome have been described in patients with asthma receiving zafirlukast treatment. This occurrence in patients being withdrawn from corticosteroid therapy while receiving zafirlukast has been attributed to a previously undiagnosed presence of this syndrome in these patients.