Diaryl triazenes inhibit cytochrome P450 1A1 and 1B1 more strongly than aryl morpholino triazenes.

Several diaryl triazene derivatives were synthesized and tested for their ability to inhibit cytochrome P450 1A1 and 1B1 as a potential means to prevent and treat cancer. These compounds are more planar than their conformational flexible aryl morpholino triazene counterparts that were previously shown to inhibit the above enzymes. As a result, the diaryl triazenes are more likely to exhibit increased binding to the enzyme active sites and inhibit these enzymes more strongly than the aryl morpholino triazenes. The data indicates that the diaryl triazenes inhibit cytochrome P450 1A1 and 1B1 one to two orders of magnitude more strongly than the aryl morpholino triazenes. Furthermore, compounds 8-10 strongly inhibited cytochrome P450 1B1 with IC50 values of 51 nM, 740 nM, and 590 nM respectively. Thus, diaryl triazenes should be further investigated as a potential chemopreventive agent.

Synthesis and in silico studies of triazene-substituted sulfamerazine derivatives as acetylcholinesterase and carbonic anhydrases inhibitors.

A novel series of sulfonamides, 4-(3-phenyltriaz-1-en-1-yl)-N-(4-methyl-2-pyrimidinyl)benzenesulfonamides (1-9), was designed and synthesized by the diazo reaction between sulfamerazine and substituted aromatic amines for the first time. Their chemical structures were characterized by 1 H nuclear magnetic resonance (NMR), 13 C NMR, and high-resolution mass spectra. The newly synthesized compounds were evaluated in terms of acetylcholineasterase (AChE) and human carbonic anhydrases (hCA) I and II isoenzymes inhibitory activities. According to the AChE inhibition results, the Ki values of the compounds 1-9 were in the range of 19.9 ± 1.5 to 96.5 ± 20.7 nM against AChE. Tacrine was used as the reference drug and its Ki value was 49.2 ± 2.7 nM against AChE. The Ki values of the compounds 1-9 were in the range of 10.2 ± 2.6 to 101.4 ± 27.8 nM against hCA I, whereas they were 18.3 ± 4.4 to 48.1 ± 4.5 nM against hCA II. Acetazolamide was used as a reference drug and its Ki values were 72.2 ± 5.4 and 52.2 ± 5.7 nM against hCA I and hCA II, respectively. The most active compounds, 1 (nonsubstituted) against AChE, 5 (4-ethoxy-substituted) against hCA I, and 8 (4-bromo-substituted) against hCA II, were chosen and docked at the binding sites of these enzymes to explain the inhibitory activities of the series. The newly synthesized compounds presented satisfactory pharmacokinetic properties via the estimation of ADME properties.

Synthesis of sulpha drug based hydroxytriazene derivatives: Anti-diabetic, antioxidant, anti-inflammatory activity and their molecular docking studies.

Herein, we report synthesis, characterization, anti-diabetic, anti-inflammatory and anti-oxidant activities of hydroxytriazenes derived from sulpha drugs, namely sulphanilamide, sulphadiazine, sulphapyridine and sulphamethazine. Before biological screening of the compounds, theoretical prediction using PASS was done which indicates probable activities ranging from Pa (probable activity) values 65-98% for anti-inflammatory activity. As per the predication, experimental validation of some of the predicted activities particularly anti-diabetic, anti-inflammatory and anti-oxidant was done. Anti-diabetic activities have been screened using two methods namely α-amylase and α-glucosidase inhibition method and IC50 values were ranging from 66 to 260 and 148 to 401 µg/mL, while for standard drug acarbose the values were 12 µg/mL and 70 µg/mL, respectively. Docking studies have also been done for antidiabetic target pancreatic alpha amylase. The molecular docking studies in α-amylase enzyme reveal that the middle phenyl ring of all the compounds mainly occupies in the small hydrophobic pocket formed by the Ala198, Trp58, Leu162, Leu165 and Ile235 residues and sulphonamide moiety establish H-bond interaction by two water molecules. Further, anti-inflammatory activity has been evaluated using carrageenan induced paw-edema method and results indicate excellent anti-inflammatory activity by hydroxytriazenes (71 to 97%) and standard drug diclofenac 94% after 4 h of treatment. Moreover, antioxidant effect of the compounds was tested using DPPH and ABTS methods. All the compounds displayed good results (24-488 µg/mL) against ABTS radical and many compounds are more active than ascorbic acid (69 µg/mL) while all other compounds showed moderate activity against DPPH radical (292-774 µg/mL) and ascorbic acid (29 µg/mL). Thus, the studies reveal potential of sulfa drug based hydroxytriazenes as candidates for antidiabetic, anti-inflammatory and antioxidant activities which have been experimentally validated.

Synthesis, characterization, biological evaluation, and in silico studies of novel 1,3-diaryltriazene-substituted sulfathiazole derivatives.

In the present study, a series of eleven novel 1,3-diaryltriazene-substituted sulfathiazole moieties (ST1-11) was synthesized by the reaction of diazonium salt of sulfathiazole with substituted aromatic amines and their chemical structures were characterized by Fourier transform infrared, 1 H-NMR (nuclear magnetic resonance), 13 C-NMR, and high-resolution mass spectroscopy methods. These synthesized novel derivatives were found to be effective inhibitor molecules for α-glycosidase (α-GLY), human carbonic anhydrase (hCA), and acetylcholinesterase (AChE), with KI values in the range of 426.84 ± 58.42-708.61 ± 122.67 nM for α-GLY, 450.37 ± 50.35-1,094.34 ± 111.37 nM for hCA I, 504.37 ± 57.22-1,205.36 ± 195.47 nM for hCA II, and 68.28 ± 10.26-193.74 ± 19.75 nM for AChE. Among the synthesized novel compounds, several lead compounds were investigated against the tested metabolic enzymes. More specifically, ST11 (4-[3-(perfluorophenyl)triaz-1-en-1-yl]-N-(thiazol-2-yl)benzenesulfonamide) showed a highly efficient inhibition profile against hCA I, hCA II, and AChE, with KI values of 450.37 ± 50.35, 504.37 ± 57.22, and 68.28 ± 10.26 nM, respectively. Due to its significant biological inhibitory potency, this derivative may be considered as an interesting lead compound against these enzymes.

Coumarin Triazabutadienes for Fluorescent Labeling of Proteins.

The use of small-molecule fluorophores to label proteins with minimal perturbation in response to an external stimulus is a powerful tool to probe chemical and biochemical environments. Herein, we describe the use of a coumarin-modified triazabutadiene that can deliver aryl diazonium ions to fluorescently label proteins by tyrosine-selective modification. The labeling can be triggered by low-pH-induced liberation of the diazonium species, thus making the fluorophore especially useful in labeling biochemical surroundings such as those found within the late endosome. Additionally, we show that a variety of coumarin triazabutadienes might also be prone to releasing their diazonium cargo after irradiation with UV light.

FLUORO/NO: A Nitric Oxide Donor with a Fluorescence Reporter.

Nitric oxide (NO) plays significant signalling roles in cells; the controlled generation of NO is of therapeutic relevance. Although a number of methods for the delivery and detection of NO are available, these events are typically mutually exclusive. Furthermore, the efficiency of delivery of NO can be compromised by detection technologies that consume NO. Here, we report FLUORO/NO, an esterase-activated diazeniumdiolate-based NO donor with an in-built fluorescence reporter. We demonstrate that this compound is capable of enhancing NO within cells in a dose-dependent manner, accompanied by a similar increase in fluorescence. The compatibility of this tool to study NO-mediated signalling as well as NO-mediated stress is demonstrated. FLUORO/NO is a convenient tool that shows NO-like activity and allows monitoring of NO release. This tool will help interrogate the redox biology of NO.

On the Formation of N3 H3 Isomers in Irradiated Ammonia Bearing Ices: Triazene (H2 NNNH) or Triimide (HNHNNH).

The remarkable versatility of triazenes in synthesis, polymer chemistry and pharmacology has led to numerous experimental and theoretical studies. Surprisingly, only very little is known about the most fundamental triazene: the parent molecule with the chemical formula N3 H3 . Here we observe molecular, isolated N3 H3 in the gas phase after it sublimes from energetically processed ammonia and nitrogen films. Combining theoretical studies with our novel detection scheme of photoionization-driven reflectron time-of-flight mass spectroscopy we can obtain information on the isomers of triazene formed in the films. Using isotopically labeled starting material, we can additionally gain insight in the formation pathways of the isomers of N3 H3 under investigation and identify the isomers formed as triazene (H2 NNNH) and possibly triimide (HNHNNH).

Aryl morpholino triazenes inhibit cytochrome P450 1A1 and 1B1.

Many cytochrome P450 1A1 and 1B1 (CYP1A1 and CYP1B1) inhibitors, such as resveratrol, have planar, hydrophobic, aromatic rings in their structure and exhibit anti-cancer activity. Aryl morpholino triazenes have similar structural features and in addition contain a triazene unit consisting of three consecutive, conjugated nitrogen atoms. Several aryl morpholino triazenes, including 4-[(E)-2-(3,4,5-trimethoxyphenyl)diazenyl]-morpholine (2), were prepared from a reaction involving morpholine and a diazonium ion produced from different aniline derivatives, such as 3,4,5-trimethoxyaniline. The aryl morpholino triazenes were then screened at 100µM for their ability to inhibit CYP1A1 and CYP1B1 using ethoxyresorufin as the substrate. Triazenes that inhibited the enzymes to less than 80% of the uninhibited enzyme activity were assayed to determine their IC50 value. Compound 2 was the only triazene to inhibit both CYP1A1 and CYP1B1 to the same degree as resveratrol with IC50 values of 10µM and 18µM, respectively. Compounds 3 and 6 selectively inhibited CYP1B1 over CYP1A1 with IC values of 2µM and 7µM, respectively. Thus, aryl morpholino triazenes are a new class of compounds that can inhibit CYP1A1 and CYP1B1 and potentially prevent cancer.

A Practical Route for the Preparation of 1,4,7-Triazacyclononanyl Diacetates with a Hydroxypyridinonate Pendant Arm.

The preparation of triazamacrocyclic hydroxypyridinonate (HOPO-TACN) derivatives as potential chelators for metals in biomedical applications was reported. The synthesis is based on a convergent synthetic approach, in which the key intermediate di-tert-butyl-2,2'-(1,4,7-triazonane-1,4-diyl) diacetate was coupled with a hydroxypyridinonate pendant arm. The method is suitable for rapid syntheses of metal chelator HOPO-TACNs of biomedical interest.

An axial chirality and disorder of positional isomers in a crystal of highly cytotoxic 3-acetyl-1,3-bis(2-chloro-4-nitrophenyl)-1E-triazene.

Biologically active 4-nitro-substituted 1,3-diaryltriazene, a chemical analogue of 1,3-bis(4'-amidinophenyl)-triazene-berenil®, belongs to the novel, chemically modified class of potent antitumor agents. Its structural characterization by X-ray analysis and 1H NMR spectroscopy is performed to determine molecular overall conformation in view of its possible interaction to DNA.

1,3-Diaryl Triazenes Incorporating Disulfonamides Show Both Antiproliferative Activity and Effective Inhibition of Tumor-associated Carbonic Anhydrases IX and XII.

AIM: The aim of this study was to synthesize a library of novel di-sulfa drugs containing 1,3- diaryltriazene derivatives TS (1-13) by conjugation of diazonium salts of primary sulfonamides with sulfa drugs to investigate the cytotoxic effect of these new compounds in different cancer types and to determine their inhibitory activity against tumor-associated carbonic anhydrases IX and XII. MATERIALS AND METHODS: A carbonic anhydrase inhibitory activity of the obtained compounds was evaluated against four selected human carbonic anhydrase isoforms (hCA I, hCA II, hCA IX and hCA XII) by a stoppedflow CO2 hydrase assay. In addition, in vitro, cytotoxicity studies were applied by using A549 (lung cancer), BEAS-2B (normal lung), MCF-7 (breast cancer), MDA-MB-231 (breast cancer), CRL-4010 (normal breast epithelium), HT-29 (colon cancer), and HCT -116 (colon cancer) cell lines. RESULTS: As a result of the inhibition data, the 4-aminobenzenesulfonamide derivatives were more active than their 3-aminobenzenesulfonamide counterparts. More specifically, compounds TS-1 and TS-2, both of which have primary sulfonamides on both sides of the triazene linker, showed the best inhibitory activity against hCA IX with Ki values of 19.5 and 13.7 nM and also against hCA XII with Ki values of 6.6 and 8.3 nM, respectively. In addition, in vitro cytotoxic activity on the human breast cancer cell line MCF-7 showed that some derivatives of di-sulfa triazenes, such as TS-5 and TS-13, were more active than SLC-0111. CONCLUSION: With the aim of developing more potent and isoform-selective CA inhibitors, these novel hybrid molecules containing sulfa drugs, triazene linkers, and the classical primary sulfonamide chemotype may be considered an interesting example of effective enzyme inhibitors and important anticancer agents.

ortho-Perfluoroalkylation and ethoxycarbonyldifluoromethylation of aromatic triazenes.

A robust protocol for perfluoroalkylation and ethoxycarbonyldifluoromethylation of functionalized aromatic triazenes is described. Using silver(I)-fluoride and different fluorinated (trimethyl)silyl substituted species, it was possible to synthesize various ortho-fluorinated triazenes in good yields via simple CH-substitution. Initial reactions under solvent-free (neat) conditions indicate a stabilizing interaction between "AgRf" and the triazene moiety, which may be responsible for the good yields and regioselectivity. The transformation possibilities of the triazene moiety make these reactions interesting for the synthesis of fluorinated building blocks. In addition, quantum chemical calculations suggest that the stabilization of the radical intermediate in the ortho-position is distinctly more favored for aromatic triazenes than for other aromatic substrates.

Push-pull triazenes derived from 1-(benzylideneamino)- and 1-(sulfonimido)-azolylidenes.

In-situ-generated neutral 1-(benzylideneamino)- and novel anionic 1-(sulfonimido)-azolylidenes react with organic azides to afford diverse classes of push-pull triazenes and triazene salts. The scope of the heterocyclic core and substituents at the N1 and N3 positions of NHC precursors together with the thermal properties of resulting compounds were examined.

Discovery of dimeric inhibitors by extension into the entrance channel of HIV-1 reverse transcriptase.

Design of non-nucleoside inhibitors of HIV-1 reverse transcriptase is being pursued with computational guidance. Extension of azine-containing inhibitors into the entrance channel between Lys103 and Glu138 has led to the discovery of potent and structurally novel derivatives including dimeric inhibitors in an NNRTI-linker-NNRTI motif.

Proof-of-Concept Study of the NOTI Chelating Platform: Preclinical Evaluation of 64Cu-Labeled Mono- and Trimeric c(RGDfK) Conjugates.

PURPOSE: We recently developed a chelating platform based on the macrocycle 1,4,7-triazacyclononane with up to three five-membered azaheterocyclic arms for the preparation of 68Ga- and 64Cu-based radiopharmaceuticals. Based on this platform, the chelator scaffold NOTI-TVA with three additional carboxylic acid groups for bioconjugation was synthesized and characterized. The primary aims of this proof-of-concept study were (1) to evaluate if trimeric radiotracers on the basis of the NOTI-TVA 6 scaffold can be developed, (2) to determine if the additional substituents for bioconjugation at the non-coordinating NH atoms of the imidazole residues of the building block NOTI influence the metal binding properties, and (3) what influence multiple targeting vectors have on the biological performance of the radiotracer. The cyclic RGDfK peptide that specifically binds to the αvß3 integrin receptor was selected as the biological model system. PROCEDURES: Two different synthetic routes for the preparation of NOTI-TVA 6 were explored. Three c(RGDfK) peptide residues were conjugated to the NOTI-TVA 6 building block by standard peptide chemistry providing the trimeric bioconjugate NOTI-TVA-c(RGDfK)3 9. Labeling of 9 with [64Cu]CuCl2 was performed manually at pH 8.2 at ambient temperature. Binding affinities of Cu-8, the Cu2+ complex of the previously described monomer NODIA-Me-c(RGDfK) 8, and the trimer Cu-9 to integrin αvß3 were determined in competitive cell binding experiments in the U-87MG cell line. The pharmacokinetics of both 64Cu-labeled conjugates [64Cu]Cu-8 and [64Cu]Cu-9 were determined by small-animal PET imaging and ex vivo biodistribution studies in mice bearing U-87MG xenografts. RESULTS: Depending on the synthetic route, NOTI-TVA 6 was obtained with an overall yield up to 58 %. The bioconjugate 9 was prepared in 41 % yield. Both conjugates [64Cu]Cu-8 and [64Cu]Cu-9 were radiolabeled quantitatively at ambient temperature in high molar activities of Am ~ 20 MBq nmol-1 in less than 5 min. Competitive inhibitory constants IC50 of c(RDGfK) 7, Cu-8, and Cu-9 were determined to be 159.5 ± 1.3 nM, 256.1 ± 2.1 nM, and 99.5 ± 1.1 nM, respectively. In small-animal experiments, both radiotracers specifically delineated αvß3 integrin-positive U-87MG tumors with low uptake in non-target organs and rapid blood clearance. The trimer [64Cu]Cu-9 showed a ~ 2.5-fold higher tumor uptake compared with the monomer [64Cu]Cu-8. CONCLUSIONS: Functionalization of NOTI at the non-coordinating NH atoms of the imidazole residues for bioconjugation was straightforward and allowed the preparation of a homotrimeric RGD conjugate. After optimization of the synthesis, required building blocks to make NOTI-TVA 6 are now available on multi-gram scale. Modifications at the imidazole groups had no measurable impact on metal binding properties in vitro and in vivo suggesting that the NOTI scaffold is a promising candidate for the development of 64Cu-labeled multimeric/multifunctional radiotracers.

Synthesis and application of a triazene-ferrocene modifier for immobilization and characterization of oligonucleotides at electrodes.

A new DNA modifier containing triazene, ferrocene, and activated ester functionalities was synthesized and applied for electrochemical grafting and characterization of DNA at glassy carbon (GC) and gold electrodes. The modifier was synthesized from ferrocenecarboxylic acid by attaching a phenyltriazene derivative to one of the ferrocene Cp rings, while the other Cp ring containing the carboxylic acid was converted to an activated ester. The modifier was conjugated to an amine-modified DNA sequence. For immobilization of the conjugate at Au or GC electrodes, the triazene was activated by dimethyl sulfate for release of the diazonium salt. The salt was reductively converted to the aryl radical which was readily immobilized at the surface. DNA grafted onto electrodes exhibited remarkable hybridization properties, as detected through a reversible shift in the redox potential of the Fc redox label upon repeated hybridization/denaturation procedures with a complementary target DNA sequence. By using a methylene blue (MB) labeled target DNA sequence the hybridization could also be followed through the MB redox potential. Electrochemical studies demonstrated that grafting through the triazene modifier can successfully compete with existing protocols for DNA immobilization through the commonly used alkanethiol linkers and diazonium salts. Furthermore, the triazene modifier provides a practical one-step immobilization procedure.

Design and synthesis of new stabilized combi-triazenes for targeting solid tumors expressing the epidermal growth factor receptor (EGFR) or its closest homologue HER2.

The monoalkyltriazene moiety lends itself well to the design of combi-molecules. However, due to its instability under physiological conditions, efforts were directed towards stabilizing it by grafting a hydrolysable carbamate onto the 3-position. The synthesis and biological activities of these novel N-carbamyl triazenes are described.

Antiviral and cytotoxic activities of aminoarylazo compounds and aryltriazene derivatives.

Twelve aminoarylazocompounds (A-C) and 46 aryltriazene 7 derivatives (D-G) have been synthesized and evaluated in cell-based assays for cytotoxicity and antiviral activity against a panel of 10 RNA and DNA viruses. Eight aminoazocompounds and 27 aryltriazene derivatives exhibited antiviral activity, sometimes of high level, against one or more viruses. A marked activity against BVDV and YFV was prevailing among the former compounds, while the latter type of compounds affected mainly CVB-2 and RSV. None of the active compounds inhibited the multiplication of HIV-1, VSV and VV. Arranged in order of decreasing potency and selectivity versus the host cell lines, the best compounds are the following; BVDV: 1>7>8>4; YFV: 7>5; CVB-2: 25>56>18; RSV: 14>20>55>38>18>19; HSV-1: 2. For these compounds the EC(50) ranged from 1.6 microM (1) to 12 microM (18), and the S. I. from 19.4 (1) to 4.2 (2). Thus the aminoarylazo and aryltriazene substructures appear as interesting molecular component for developing antiviral agents against ss RNA viruses, particularly against RSV and BVDV, which are important human and veterinary pathogens. Finally, molecular modeling investigations indicated that compounds of structure A-C, active against BVDV, could work targeting the viral RNA-dependent RNA-polymerase (RdRp), having been observed a good agreement between the trends of the estimated IC(50) and the experimental EC(50) values.

Targeting gliomas with triazene-based hybrids: Structure-activity relationship, mechanistic study and stability.

Herein we report novel hybrid compounds based on valproic acid and DNA-alkylating triazene moieties, 1, with therapeutic potential for glioblastoma multiforme chemotherapy. We identified hybrid compounds 1d and 1e to be remarkably more potent against glioma and more efficient in decreasing invasive cell properties than temozolomide and endowed with chemical and plasma stability. In contrast to temozolomide, which undergoes hydrolysis to release an alkylating metabolite, the valproate hybrids showed a low potential to alkylate DNA. Key physicochemical properties align for optimal CNS penetration, highlighting the potential of these effective triazene based-hybrids for enhanced anticancer chemotherapy.

Synthesis, radiosynthesis, and biological evaluation of new proteasome inhibitors in a tumor targeting approach.

Proteasome inhibition is a new strategy in cancer therapy. We synthesized three new peptide aldehyde inhibitors linked to the benzamide derivative structure to use their cytotoxic activity against malignant melanoma cells. Of these, 10 displayed the highest cytotoxicity (0.18 +/- 0.16 microM). A radiosynthesis of the iodine aldehyde was performed. Its drug biodistribution showed that some selectivity of the benzamide group toward malignant melanoma tissue was conserved.