Piyush Kumar

Tumour hypoxia negatively impacts therapy outcomes and continues to be a major unsolved clinical problem. Nitroimidazoles are hypoxia selective compounds that become entrapped in hypoxic cells by forming drugprotein adducts. They are widely used as hypoxia diagnostics and have also shown promise as hypoxiadirected therapeutics. However, little is known about the protein targets of nitroimidazoles and the resulting effects of their modification on cancer cells. Here, we report the synthesis and applications of azidoazomycin arabinofuranoside (N 3-AZA), a novel click-chemistry compatible 2-nitroimidazole, designed to facilitate (a) the LC-MS/MS-based proteomic analysis of 2-nitroimidazole targeted proteins in FaDu head and neck cancer cells, and (b) rapid and efficient labelling of hypoxic cells and tissues. Bioinformatic analysis revealed that many of the 62 target proteins we identified participate in key canonical pathways including glycolysis and HIF1A signaling that play critical roles in the cellular response to hypoxia. Critical cellular proteins such as the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and the detoxification enzyme glutathione S-transferase P (GSTP1) appeared as top hits, and N 3-AZA adduct formation significantly reduced their enzymatic activities only under hypoxia. Therefore, GAPDH, GSTP1 and other proteins reported here may represent candidate targets to further enhance the potential for nitroimidazole-based cancer therapeutics.

Purpose: 18F-Fluoroestradiol [18F]FES has emerged as a valuable PET tracer to predict the response to hormone therapy in recurrent or metastatic breast cancer patients. A clinically acceptable product requires a rapid reliable synthesis and must be demonstrated to maintain chemical stability and receptor specific uptake during patient studies. [18F]FES then becomes a dependable tracer for the evaluation and management of breast cancer patients. Methods: An improved automated radiosynthesis of [18F]FES was developed. Stability studies of the injectible form of [18F]FES were performed up to 24 h after dose formulation under normal storage conditions. A comparative FES/FDG PET imaging in ER+ breast cancer patients is reported. Results: The improved synthesis procedure utilizes fewer hydrolysis steps and a single high performance liquid column chromatography (HPLC) purification of the labeled mixture affording [18F]FES in good yield with high radiochemical purity (>99%). Stability studies with purified [18F]FES in saline/ethanol (85:15 v/v) indicated no radiolytic or chemical degradation of this radiopharmaceutical when stored for 24 h at 20-24 degrees C. Positron Emission Tomography (PET) studies with [18F]FES and [18F]FDG in estrogen receptor positive (ER+) breast cancer patients indicated that while FDG accumulation was seen in all metabolically hyperactive sites, the uptake of FES clearly delineated the ER+ tissues regions. Conclusions: An improved automated synthesis of [18F]FES has been developed and the integrity of this product has been validated by long term stability studies and clinical PET imaging studies in ER+ breast cancer patients. A lack of concordance between FES and FDG uptake in a patient with metastatic breast cancer suggests specificity of the FES for tumors expressing estrogen receptors.

A group of N-substituted-1,4-dihydropyridylacetic acids (13-16), esters (4-12), and amides (17-23) were synthesized in order to investigate the effect of 4-substituents (R2 = Ph, n-Bu or Me) and alpha-substituents (R3 = H, Me) on antiinflammatory activity. In the acetic ester class of compounds, the relative activities (R2-substituents) were Ph greater than n-Bu greater than Me. The presence of an R3 methyl substituent enhanced activity. Increasing the length of the alkyl ester substituent enhanced activity, since the tri-ester (7) was more active than the bis-ester (6), and the bis-ester (11) was more active than the mono-ester (10). The relative order of antiinflammatory potency was generally ester greater than amide greater than acid. Methyl 2-methyl-2-(-1-[4-phenyl-3-(4,4-dimethyloxazolin-2-yl)-1,4-dihy dropyridyl]) acetate (9) was the most active antiinflammatory agent in the series, reducing inflammation 73.9% at 3 hr after a 100 mg/kg po dose.

The current work evaluates 1-alpha-d-(2-deoxy-2-fluororibofuranosyl)-2-nitroimidazole (FRAZ), a novel azomycin nucleoside that is a potential radiosensitizer of tumor hypoxia. FRAZ is a ribose analogue of 1-alpha-d-(2-deoxy-2-fluoroarabinofuranosyl)-2-nitroimidazole ([(18)F]-FAZA), a clinically used hypoxia marker. Preliminary assessment of the cytotoxicity and hypoxia-specific in vitro binding in HCT-110 colorectal cancer cells indicate that the radiosensitization properties of FRAZ are similar to that of FAZA, with a sensitizer enhancement ratio (SER) of approximately 1.8. An automated radiosynthesis of [(18)F]-FRAZ using a commercial automated synthesis unit (ASU) was established (synthesis time approximately 32 min; radiochemical yield (decay uncorrecetd) approximately 22%) to facilitate its application in PET-based diagnosis of hypoxic tumors.

... Manju TANDON a1, Piyush KUMAR b1,*, Haiyan XIA a2,+, Lili WANG a3,+ and ... Lowe and Brydone Ltd., London 1956. 7. Chernyak AY, Sharma GVM, Kononov LO, Radha Krishna P., Rama Rao AV, Kochetkov NK: Glycoconjugate J. 1991, 8, 82. 8. Konecny JO: J. Am. Chem. ...

Index Medicus for South-East Asia Region (IMSEAR) is a compiled and maintained by Information Management and Dissemination Unit, Department of Sustainable Development and Healthy Environments, World Health Organization, Regional Office for South-East Asia.

A group of N-substituted-1,4-dihydropyridylacetic acids (13-16), esters (4-12), and amides (17-23) were synthesized in order to investigate the effect of 4-substituents (R2 = Ph, n-Bu or Me) and alpha-substituents (R3 = H, Me) on antiinflammatory activity. In the acetic ester class of compounds, the relative activities (R2-substituents) were Ph greater than n-Bu greater than Me. The presence of an R3 methyl substituent enhanced activity. Increasing the length of the alkyl ester substituent enhanced activity, since the tri-ester (7) was more active than the bis-ester (6), and the bis-ester (11) was more active than the mono-ester (10). The relative order of antiinflammatory potency was generally ester greater than amide greater than acid. Methyl 2-methyl-2-(-1-[4-phenyl-3-(4,4-dimethyloxazolin-2-yl)-1,4-dihy dropyridyl]) acetate (9) was the most active antiinflammatory agent in the series, reducing inflammation 73.9% at 3 hr after a 100 mg/kg po dose.

A series of 5-(pyridyl)-2H-tetrazol-2-acetic acids (16-21), esters (10-15), and amides (22-27) was synthesized in order to investigate the effect of 5-substituents (R1 = 2-, 3- or 4-pyridyl) and alpha-substituents (R2 = H, Me) on anti-inflammatory activity. The point of attachment of the R1-pyridyl substituent influenced potency. The relative potencies in the acetic acid ester, acetic acid and acetamide classes of compounds were 2- and 4- greater than 3-pyr, 2- and 3- greater than 4-pyr, and 4- greater than 2- and 3-pyr, respectively. In the acetic acid ester and acetamide classes, compounds having a R2 hydrogen substituent were generally more potent than corresponding methyl substituted compounds, whereas, in the acetic acid class the reverse applied. The relative order of anti-inflammatory potency was generally amide greater than ester greater than acid. 2-[5-(4-Pyridyl)-2H-tetrazol-2-yl]acetamide (26) was the most effective antiinflammatory agent in the series, reducing inflammat...

... Manju Tandon, Piyush Kwnar and Leonard I. Webe * Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta, Canada T6G 2N8 ... antiviral properties, especially in the treatment of ophthalmic herpetic infections (Carmine et al, 1982). ...

... PIYUSH KUMAR AND JOHN R. MERCER ... Potential radionuclides from impurities in the target H2 18O water, and released from the metal targets and foils, can be detected by their characteristic γ-ray emissions. A test sample of 18F − in H2 18O is placed ...

... Danielle Leblois a , Sylvie Piessard a , Guillaume Le Baut Corresponding Author Contact Information , a , Corresponding Author Contact Information , Piyush Kumar a , Jean-Daniel Brion a , Louis Sparfel a , René-Yann Sanchez b , Marcel Juge b ... Ther. 230, 279 Saad MH BurkaJ ...

The reduction potentials of bioreductively-activated drugs represent an important design parameter to be accommodated in the course of creating lead compounds and improving the efficacy of older generation drugs.  Reduction potentials are traditionally reported as single–electron reduction potentials, E(1), measured against reference electrodes under strictly defined experimental conditions.  More recently, computational chemists have described redox properties in terms of a molecule’s highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO), in electron volts (eV).  The relative accessibility of HOMO/LUMO data through calculation using today’s computer infrastructure and simplified algorithms make the calculated value (LUMO) attractive in comparison to the accepted but rigorous experimental determination of E(1).  This paper describes the correlations of eV (LUMO) to E(1) for three series of bioreductively–activated benzotriazine di-N-oxides (BTDOs),...

2'-Deoxy-2'-fluorothymidine (FT) is a bioisostere of both thymidine (TdR), in which F replaces H at C-2' in the ribosyl configuration, and methyluridine, in which F replaces OH at C-2' in the ribosyl configuration. Fluorine is bioisosteric with H with respect to atomic radius and is bioisosteric with OH with respect to polarity and H-bonding as an H acceptor. The consequences of this C-2' F for H substitution on cytotoxicity, nucleoside transporter affinity, phosphorylation by thymidine kinases (TK1, TK2), cell uptake and biodistribution of FT in a murine tumor model are now reported. FT toxicity against a bank of murine and human cells was seen only at very high (˜1 mM) concentrations, although the cellular uptake of [3H]FT in these cells was comparable to that of [3H]TdR over a 24 h period. Human equilibrative nucleoside transporters (hENT1, hENT2) displayed weaker affinity for FT than for TdR, but the concentrative transporters (hCNT1, hCNT2, hCNT3) had much h...

Several F-18-labeled 2-nitroimidazole (azomycin) derivatives have been proposed for imaging hypoxia using positron emission tomography (PET). Their cell penetration is based on passive diffusion, which limits their intracellular concentration maxima. The purpose of this study was to investigate the uptake of N-(2-[(18)F]fluoro-3-(6-O-glucosyl)propyl-azomycin ([(18)F]F-GAZ), a new azomycin-glucose conjugate, in vitro and in vivo. [(18)F]F-GAZ was synthesized from its tetraacetyl nosylate precursor by nucleophilic radiofluorination. [(18)F]F-GAZ was evaluated in vivo in EMT-6 tumor-bearing Balb/C mice utilizing the PET and biodistribution analysis. In vitro uptake of [(18)F]FDG by EMT-6 cells was measured in the presence of unlabeled F-GAZ, 2-FDG, and D-glucose. [(18)F]F-GAZ was rapidly cleared from all tissues, including the blood pool and kidneys, with ultimate accumulation in the urinary bladder. Uptake of tracer doses of [(18)F]F-GAZ into EMT-6 tumors was fast, reaching a standardized uptake value of 0.66±0.05 within 5-6 minutes postinjection (p.i.), and decreased to 0.24±0.04 by 60 minutes p.i. (n=6). A tumor-muscle ratio of 1.87±0.18 was observed after 60 minutes. Total uptake of [(18)F]F-GAZ in tumors (60 minutes) amounted to 1.25%±0.15% ID/g versus 0.61%±0.14% ID/g (n=4) in muscle. Similar biodistribution and excretion were observed using carrier-added (100 mg/kg) doses of F-GAZ. In vitro, D-glucose and unlabeled 2-FDG were two orders of magnitude more potent than F-GAZ as competitive inhibitors of [(18)F]FDG uptake into EMT-6 cells. Besides its interaction with glucose transporters, F-GAZ seems to be not transported in the presence of glucose. Furthermore, [(18)F]F-GAZ is unlikely to be effective as a hypoxia imaging agent. The low in vivo toxicity and substantial retention in tumor observed at high doses of F-GAZ do provide rationale for further testing as a radiosensitizer for external beam radiation therapy of radioresistant, hypoxic tumors.

The present work describes the synthesis of the beta -isomer of 1alpha -D-(5-deoxy-5-iodoarabinofuranosyl)-2-nitroimidazole (IAZA). Radioiodinated IAZA (123I-IAZA) has been extensively studied as a radiopharmaceutical for the diagnosis of regional and/or focal tissue hypoxia in a variety of clinical pathologies. The beta-anomer of IAZA, 1beta -D-(5-deoxy-5-iodoarabinofuranosyl)-2-nitroimidazole ( beta-IAZA, 1), was synthesized via an unconventional route starting from 1beta-D-(ribofuranosyl)-2-nitroimidazole (AZR), with a change of configuration at the C2'-position. Nucleophilic iodination of the 5'-O-toluenesulfonyl-2',3'-di-O-acetyl precursor of beta-AZA, 9, followed by deprotection, afforded 1 in satisfactory yield. Beta-IAZA (1) was also synthesized from 7 using molecular iodine and triphenylphosphine.