Investigation on the impact of three different quaternary methyl ammonium cartridges on the radiosynthetic yields of [18 F]fluoromethyl tosylate.

Our recent investigations for the radiosynthesis of [18 F]fluoromethyl tosylate have highlighted that choice of quaternary methyl ammonium (QMA) cartridge used during the radiosynthesis can significantly impact the radiochemical yields. Often the details of the QMA cartridge used in fluourine-18 syntheses are not fully described. However, our studies demonstrate that the type, the size, and nature (method by which it has been conditioned) of the QMA cartridge used during the radiosynthesis can make a significant impact in the labelling efficiency. This paper investigates the use of three QMA cartridges and demonstrates that radiochemical yield (decay corrected) of [18 F]fluoromethyl tosylate can increase from 46% to 60% by simply changing the QMA cartridge (and leaving all other reagents and labelling conditions exactly the same). These learnings may be applied to improve the radiochemical yields of a number of [18 F]-fluorinated tracers (and synthons), where the labelling step is base-sensitive to increase the radiochemical yield, thereby significantly benefiting the radiochemistry and nuclear medicine community. This paper also highlights the necessity of the radiochemistry community to ensure the details of QMA cartridges used in fluorine-18 chemistry are fully and accurately described, since this will improve the translation of radiochemical methods from one laboratory to another.

Synthesis of 18 F-radiolabeled diphenyl gallium dithiosemicarbazone using a novel halogen exchange method and in vivo biodistribution.

18 F-radiolabeled diphenyl gallium thiosemicarbazone was prepared by [18 F] fluoride exchange of a nitrato anion under mild conditions. The diphenyl gallium thiosemicarbazone chloride is easily prepared in gram quantities and can be used at room temperature in the presence of oxygen. The corresponding nitrate complex is prepared using silver nitrate in methanol solvent and can be stored under nitrogen for weeks before radiolabeling. The biodistribution of this new tracer was studied in mice using positron emission tomography (PET).

Investigation of two- and three-bond carbon-hydrogen coupling constants in cinnamic acid based compounds.

Two- and three-bond coupling constants (2 JHC and 3 JHC ) were determined for a series of 12 substituted cinnamic acids using a selective 2D inphase/antiphase (IPAP)-single quantum multiple bond correlation (HSQMBC) and 1D proton coupled 13 C NMR experiments. The coupling constants from two methods were compared and found to give very similar values. The results showed coupling constant values ranging from 1.7 to 9.7 Hz and 1.0 to 9.6 Hz for the IPAP-HSQMBC and the direct 13 C NMR experiments, respectively. The experimental values of the coupling constants were compared with discrete density functional theory (DFT) calculated values and were found to be in good agreement for the 3 JHC . However, the DFT method under estimated the 2 JHC coupling constants. Knowing the limitations of the measurement and calculation of these multibond coupling constants will add confidence to the assignment of conformation or stereochemical aspects of complex molecules like natural products. Copyright © 2016 John Wiley & Sons, Ltd.

Synthesis and characterization of benzothiazolyl-substituted anils.

New Schiff bases containing a hydroxynaphthyl ring and substituted benzothiazolyl groups have been synthesized. High-resolution NMR spectra confirmed that these anils exist as enol-keto tautomers in solution. The results from NMR data demonstrated that the proportion of enol tautomer exceeded 90% in these substituted anils. Some compounds exhibited thermochromism in solid state.

Structural investigation on phenyl- and pyridin-2-ylamino(methylene)naphthalen-2(3H)-one. Substituent effects on the NMR chemical shifts.

Schiff bases bearing phenyl and pyridyl groups were synthesized by condensation of appropriate amines with 2-hydroxynaphthaldehyde. These Schiff bases were obtained as colored crystalline solids. The proton NMR spectra of these compounds showed a doublet for the NH protons indicating a keto tautomer for these Schiff bases. The pyridyl-substituted Schiff bases containing hydroxyl moiety were found to show the most downfield shift for the NH protons in DMSO solvent, and this was rationalized due to the formation of a six- and five-membered ring using hydrogen bonds for these two compounds. Correspondingly, the olefinic proton of the Schiff bases is also found to be a doublet due to coupling to the amine proton. These Schiff bases exhibited thermochromic properties. Detailed NMR spectral analysis for both the phenyl- and pyridyl-substituted Schiff bases is presented.

Targeted and modular architectural polymers employing bioorthogonal chemistry for quantitative therapeutic delivery.

There remain several key challenges to existing therapeutic systems for cancer therapy, such as quantitatively determining the true, tissue-specific drug release profile in vivo, as well as reducing side-effects for an increased standard of care. Hence, it is crucial to engineer new materials that allow for a better understanding of the in vivo pharmacokinetic/pharmacodynamic behaviours of therapeutics. We have expanded on recent "click-to-release" bioorthogonal pro-drug activation of antibody-drug conjugates (ADCs) to develop a modular and controlled theranostic system for quantitatively assessing site-specific drug activation and deposition from a nanocarrier molecule, by employing defined chemistries. The exploitation of quantitative imaging using positron emission tomography (PET) together with pre-targeted bioorthogonal chemistries in our system provided an effective means to assess in real-time the exact amount of active drug administered at precise sites in the animal; our methodology introduces flexibility in both the targeting and therapeutic components that is specific to nanomedicines and offers unique advantages over other technologies. In this approach, the in vivo click reaction facilitates pro-drug activation as well as provides a quantitative means to investigate the dynamic behaviour of the therapeutic agent.

Targeting JAK3 and BTK tyrosine kinases with rationally-designed inhibitors.

Multifunctional rational drug design of protein tyrosine kinases inhibitors allows a potent drug to be utilized to treat more than one disease for greater patient benefits. Many protein tyrosine kinases (PTK), including Janus kinase 3 (JAK3) and Bruton's tyrosine kinase (BTK), have been identified as potential drug targets to treat diverse diseases including cancer and disorders of the immune system. Here we review advances in JAK3 and BTK inhibitors and describe the therapeutic potential of these potent agents in the clinical setting.

Synthesis, characterization and biological activities of semicarbazones and their copper complexes.

Substituted semicarbazones/thiosemicarbazones and their copper complexes have been prepared and several single crystal structures examined. The copper complexes of these semicarbazone/thiosemicarbazones were prepared and several crystal structures examined. The single crystal X-ray structure of the pyridyl-substituted semicarbazone showed two types of copper complexes, a monomer and a dimer. We also found that the p-nitrophenyl semicarbazone formed a conventional 'magic lantern' acetate-bridged dimer. Electron Paramagnetic Resonance (EPR) of several of the copper complexes was consistent with the results of single crystal X-ray crystallography. The EPR spectra of the p-nitrophenyl semicarbazone copper complex in dimethylsulfoxide (DMSO) showed the presence of two species, confirming the structural information. Since thiosemicarbazones and semicarbazones have been reported to exhibit anticancer activity, we examined the anticancer activity of several of the derivatives reported in the present study and interestingly only the thiosemicarbazone showed activity while the semicarbazones were not active indicating that introduction of sulphur atom alters the biological profile of these thiosemicarbazones.

Effect of stereo and regiochemistry towards wild and multidrug resistant HIV-1 virus: viral potency of chiral PETT derivatives.

Chiral derivatives of several substituted halopyridyl and thiazolyl PETT compounds were synthesized as non-nucleoside inhibitors of the reverse transcriptase (RT) enzyme of the human immunodeficiency virus (HIV-1). Molecular modeling studies indicated that because of the asymmetric geometry of the non-nucleoside inhibitors (NNRTI) binding pocket, the "R" stereoisomers would fit the NNRTI binding pocket of the HIV-1 RT much better than the corresponding "S" stereoisomers, as reflected by their 10(4)-fold lower K(i) values. The "R" stereoisomers of several PETT derivatives inhibited the recombinant RT in vitro with lower IC(50) values than their enantiomers. The active compounds were further evaluated for their ability to inhibit HIV-1 replication in human peripheral blood mononuclear cells (PBMCs). All the "R" isomers again showed potent anti-HIV activity and inhibited the replication of the HIV-1 strains HTLV(IIIB) in PBMCs at nanomolar concentrations whereas their enantiomers were less potent. The lead compounds for the respective groups were further tested against A17 (NNRTI-resistant, Y181C mutant RT), and A17Var (NNI-resistant Y181C +/- K103N mutant RT) as well as multidrug resistant viral strains. The results indicated that the lead compounds were several logs more potent than the standard NNRTI drug nevirapine. Structure-activity relationship among the derivatives showed preference of pyridyl unit with halo substitutions primarily at 5-position demonstrating the importance of both the stereochemistry as well as regiochemistry. Our data provides experimental evidence that the stereochemistry and the regiochemistry of non-nucleoside inhibitors can profoundly affect their anti-HIV activity.

Large-scale synthesis of GMP grade N'- [2-(2-thiophene) ethyl]-N'- [2- (5-bromopyridyl)] -thiourea (HI-443), a new anti-HIV drug candidate.

The thiourea compound N'-[2-(2-thiophene)ethyl]-N'-[2-(5-bromopyridyl)]-thiourea (HI-443, CAS 258340-15-7), was found to be a potent anti-HIV agent with remarkable activity against nucleoside analog reverse transcriptase (NRT)-resistant, non-nucleoside analog reverse transcriptase (NNRT)-resistant, as well as multidrug-resistant HIV. Now the method of producing HI-443 under current Good Manufacturing Practice (cGMP) conditions on the scale of kilograms is reported. The availability of GMP-grade HI-443 will promote the preclinical and clinical development efforts aimed at making this new drug candidate available to HIV-infected persons.

Large-scale synthesis of GMP grade alpha-cyano-beta-hydroxy-beta-methyl-N-(2,5-dibromophenyl) propenamide (LFM-A13), a new anti-cancer drug candidate.

The leflunomide (CAS 75706-12-6) metabolite (LFM) analog alpha-cyano-beta-hydroxy-beta-methyl-N-(2,5-dibromophenyl)-propenamide (LFM-A13, DDE-28, CAS 244240-24-2), is a rationally designed inhibitor of the anti-apoptotic enzyme Bruton's tyrosine kinase (BTK). LFM-A13 is being developed as a novel dual-function anticancer drug with apoptosis-promoting and anti-thrombotic properties. LFM-A13 was prepared under current Good Manufacturing Practice (cGMP) conditions on the scale of kilograms.

Anti-retroviral activity of GMP-grade stampidine against genotypically and phenotypically nucleoside reverse transcriptase inhibitor resistant recombinant human immunodeficiency virus. An in vitro study.

The in vitro potency of GMP-grade stampidine (CAS 217178-62-6) was examined against 3 clinical HIV-1 isolates and 6 recombinant HIV-1 clones with multi-NRTI 'resistance (NRTI: nucleoside reverse transcriptase inhibitors). GMP-grade stampidine active drug substance (Lot #'s MPR-M0008.00-01 and MPR-M0008.01-01) as well as GMP-grade stampidine extracted from the clinical stampidine capsules (GMP-Grade Clinical Batch, Pharmaceutical Service Lot Number 159I0601) were highly potent and exhibited nanomolar IC50 values against clinical HIV-1 isolates as well as recombinant HIV-1 clones with multi-NRTI resistance containing common patterns of reverse transcriptase mutations responsible for NRTI resistance.

In vivo pharmacokinetics and toxicity of a novel hydrophilic oral formulation of the potent non-nucleoside reverse transcriptase inhibitor compound N'-[2-(2-thiophene)ethyl]-N'-[2-(5-bromopyridyl)]-thiourea (HI-443).

The thiophene ethyl thiourea (TET) compound N'-[2-(2-thiophene)ethyl]-N'-[2-(5-bromopyridyl)]-thiourea (HI-443) is a potent non-nucleoside reverse transcriptase inhibitor (NNRTI). The pharmacokinetics of 17 different novel oral formulations of HI-443 were compared in an attempt to identify the most suitable dosage form for clinical use in HIV-infected persons. Plasma concentrations of HI-443 were monitored in mice after administration of the drug using these 17 different formulations at three time points. Two-way ANOVA showed highly significant formulation (p < 0.0001), time (p < 0.0001) and formulation*time interaction effects (p = 0.0003). Planned linear contrasts were performed to identify which formulations showed the highest bioavailability at 10, 30, 60 min and at all time points relative to DMSO alone. A significant positive regression was observed comparing bioavailibility of HI-443 at 10 min and hydrophilic-lipophilic balance (HLB) values of the formulations (R2 = 26%, p < 0.0001). The results showed that formulations that were hydrophilic, containing PEG400 and propylene glycol, gave the highest overall drug concentrations over the 60-min time period. The lead oral formulation of HI-443 exhibited a very favorable toxicity profile in BALB/c mice.

Improved oral bioavailability of anti-HIV agent N'-[2-(2-thiophene)ethyl]-N'-[2-(5-bromopyridyl)]-thiourea (HI-443) in a novel lipophilic formulation.

N'-[2-(2-Thiophene)ethyl]-N'-[2-(5-bromopyridyl)]-thiourea (CAS 258340-15-7, HI-443) is a rationally designed non-nucleoside reverse transcriptase inhibitor (NNRTI) with potent anti-HIV activity at nanomolar concentrations but poor oral bioavailability. Here the identification of a novel oleic acid containing lead formulation of HI-443 is described which resulted in a approximately 10-fold improvement of its oral bioavailability yielding 10-fold higher systemic exposure levels in mice. Formulated HI-443 exhibited a favorable pharmacokinetics and toxicity profile in mice.

In vivo pharmacokinetics, metabolism, toxicity, and anti-HIV activity of N'-[2-(2-Thiophene)ethyl]-N'-[2-(5-bromopyridyl)]thiourea (HI-443), a potent non-nucleoside inhibitor of HIV reverse transcriptase.

N'-[2-(2-Thiophene)ethyl]-N'-[2-(5bromopyridyl)]thiourea (CAS 258340-15-7, HI-443) is a potent non-nucleoside inhibitor of HIV reverse transcriptase (NNRTI) that was rationally designed as a candidate anti-HIV agent. The purpose of the present study was to examine the in vivo pharmacokinetics, metabolism, toxicity, and anti-HIV activity of HI-443. HI-443 was very well tolerated in CD-1 mice and Lewis rats without any detectable toxicity at single parenteral bolus dose levels as high as 80 mg/kg. Intraperitoneally administered HI-443 exhibited anti-HIV activity in the Hu-PBL-SCID mouse surrogate model for hunnan AIDS at a non-toxic daily dose level of 10-20 mg/kg. These preclinical research studies provide the basis for future preclinical studies and clinical development of HI-443 as a new NNRTI candidate.

Large-scale synthesis and formulation of GMP-grade stampidine, a new anti-HIV agent.

The arylphosphoramidate derivative of stavudine (STV, d4T, 2,3'-didehydro-3'-deoxythymidine, CAS 3056-17-5), stampidine (STAMP, DDE-113, HI-113, N-[p-(4-bromophenyl)-2',3'-didehydro-3'-deoxy-5'-thymidylyl]-L-alanine methyl ester, CAS 217178-62-6), is a novel anti-HIV agent. STAMP was prepared under current Good Manufacturing Practice (cGMP) conditions on the scale of kilograms. Solid STAMP was subsequently formulated as a capsule under GMP conditions for oral administration.

Synthesis, separation and anti-HIV activity of distereoisomers of N-[p-(4-bromophenyl) -2',3'-didehydro-3'-deoxy-5'-thymidylyl]-L-alanine methyl ester (stampidine).

The distereoisomers of stampidine (STAMP, DDE-113, HI-113, N-[p-(4-bromophenyl)-2'3'-didehydro-3'-deoxy-5'-thymidylyl]-L-alanine methyl ester, CAS 217178-62-6) were separated using two different procedures. The first method involved separation of the isomers by fractional crystallization, and the second method utilized a preparative HPLC. Both isomers were active against the HIV-1 strain HTLV(IIIB) and neither isomer was more or less active than distereoisomeric mixture of stampidine.

Site-specific enzymatic activation of the anti-HIV agent stampidine.

Stampidine (STAMP, DDE-113, HI-113, N-[p-(4-bromophenyl)-2',3'-didehydro-3'-deoxy-5'-thymidylyl]-L-alanine methyl ester, CAS 217178-62-6) and two stampidine analogs containing ethyl or t-butyl groups were synthesized and their rates of enzymatic activation were compared side-by-side. Enzymes such as lipase, esterase and protease did not hydrolyze the butyl substituted STAMP analog. These experimental results show that the site of attack for the enzymatic hydrolysis of STAMP is the ester side chain of the molecule.

Potency of stampidine against multi-nucleoside reverse transcriptase inhibitor resistant human immunodeficiency viruses.

The in vitro potency of stampidine (STAMP, DDE-113, HI-113, N-[p-(4-bromophenyl)-2',3'-didehydro-3'-deoxy-5'-thymidylyl]-L-alanine methyl ester, CAS 217178-62-6) was examined against 8 clinical non-B subtype HIV-1 isolates with resistance to stavudine (STV, d4T), adefovir and tenofovir, 19 clinical zidovudine-resistant HIV-1 isolates, and 6 recombinant HIV-1 clones with multi-resistance against nucleoside reverse transcriptase inhibitors. Stampidine exhibited potent anti-HIV activity against each one of these 33 HIV-1 isolates with subnanomolar to nanomolar IC50 values.

In vivo pharmacokinetics and toxicity profile of the anti-HIV agent stampidine in dogs and feline immunodeficiency virus-infected cats.

The pharmacokinetics and toxicity profile of stampidine (STAMP, DDE-113, HI-113, N-[p-(4-bromophenyl)-2',3'-didehydro-3'-deoxy-5'-thymidylyl]-L-alanine methyl ester, CAS 217178-62-6) were studied in beagle dogs and feline immunodeficiency virus-infected domestic cats. Therapeutic plasma concentrations of STAMP 3-4 logs higher than its IC50 value can be achieved after its p.o. administration to dogs as well as cats at the 100 mg/kg nontoxic dose level. In accordance with its safety profile in rodent species, a 4- to 7-week STAMP treatment course with twice daily administration of hard gelatin capsules containing 25-100 mg/kg (50-200 mg/kg/ day) STAMP was very well-tolerated by dogs and cats at cumulative dose levels as high as 8.4 g/kg. Except for the sporadic occurrence of nausea and vomiting after its administration and elevation of serum ALT levels in some of the cats, STAMP therapy was not associated with any clinical or laboratory evidence of toxicity. No STAMP-related toxic lesions were found in any of the organs from STAMP-treated cats or dogs. These findings encourage the further development of stampidine for possible clinical use in HIV-infected persons.