104292-51-5Relevant articles and documents
Hypoxia-selective nitrobenzyloxycarbonyl derivatives of 1,2- bis(methylsulfonyl)-1-(2-chloroethyl)hydrazines
Shyam, Krishnamurthy,Penketh, Philip G.,Shapiro, Maxim,Belcourt, Michael F.,Loomis, Regina H.,Rockwell, Sara,Sartorelli, Alan C.
, p. 941 - 946 (1999)
Some 4- and 2-(nitrobenzyloxycarbonyl)-1,2-bis(methylsulfonyl)-1-(2- chloroethyl)hydrazines (4, 6, and 7) were synthesized and evaluated for their ability to exert preferential toxicity to hypoxic EMT6 mammary carcinoma cells using a colony-forming assay. Of these, the 4,5-dimethoxy-2-nitro analogue 6 (50 μM, 1-h exposure) caused greater than 3 logs of kill of hypoxic cells, with relatively minor toxicity to corresponding aerobic cells. The ability of 4-nitro (4) and 4,5-dimethoxy-2-nitro (6) analogues to reach and kill hypoxic cells of solid tumors was also demonstrated using intradermally implanted EMT6 solid tumors in mice. In addition, a possible source of toxicity to normal tissue, i.e., the activation of the 4- nitrobenzyl derivative 4 by glutathione S-transferase-catalyzed thiolysis, was essentially eliminated by replacing one of the benzylic methylene protons by a methyl group. The 4-nitro (4) and 4,5-dimethoxy-2-nitro (6) analogues also appear to be reduced more easily under acidic conditions (pH 6.0) than under neutral conditions, as measured by differential pulse polarography. Since the pH in hypoxic regions is often lower than that in adjacent aerobic regions, this property should aid in the cytotoxic action of these agents against hypoxic cells of solid tumors.
BIOREDUCTIVELY-ACTIVATED PRODRUGS
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Page/Page column 39, (2010/10/20)
The present invention relates to a compound of formula (1), or a pharmaceutically acceptable salt thereof, Formula: (1); wherein: R1 is a substituted aryl or heteroaryl group bearing at least one nitro or azido group or is an optionally substituted benzoquinone, optionally substituted naphthoquinone or optionally substituted fused heterocycloquinone; R2 is H, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted cycloalkyl, optionally substituted heterocycloalkyl, aryl or heteroaryl; and R3 is selected such that R3NH2 represents a cytotoxic nucleoside analogue or an ester or phosphate ester prodrug of a cytotoxic nucleoside analogue, with the proviso that if R1 is an aryl group then R2 is not H.
Substituent effects on the kinetics of reductively-initiated fragmentation of nitrobenzyl carbamates designed as triggers for bioreductive prodrugs
Hay, Michael P.,Sykes, Bridget M.,Denny, William A.,O'Connor, Charmian J.
, p. 2759 - 2770 (2007/10/03)
4-Nitrobenzyl carbamates are of interest as triggers for bioreductive drugs, particularly in conjunction with the E. coli B nitroreductase, which efficiently reduces them to the corresponding hydroxylamines. These then fragment to release highly toxic amine-based toxins. While many 4-nitrobenzyl carbamate derivatives have been evaluated as bioreductive drugs, there has been no systematic study of substituent effects on the rate of this fragmentation (which should be as fast as possible following reduction). We therefore prepared a series of 2-, 3- and α-substituted 4-[N-methyl-N-(4-nitrobenzyloxycarbonyl)amino]phenylacetamides as model compounds to study these effects. The majority of the carbamates were prepared by in situ formation of the chloroformate of the appropriate 4-nitrobenzyl alcohol and reaction with methyl 4-(methylamino)phenylacetate, followed by ester hydrolysis and 1,1′-carbonyl-diimidazole (CDI) mediated coupling with N,N-dimethylaminoethylamine. The hydroxylamines were generated by 60Co γ-ray irradiation of the nitro compounds in aqueous phosphate-buffered-propan-2-ol. The reactions were analysed by reverse-phase HPLC to determine the maximum half-life (Mt1/2) of the hydroxylamines generated, and the extent of release of amine from these after 10 half-lives (t∞). The parent (unsubstituted) hydroxylaminobenzyl carbamate had a Mt1/2 of 16 min under these conditions, while that of the corresponding α-methyl analogue was 9.5 min. Electron-donating substituents on the benzyl ring also accelerated fragmentation, with the data being fitted to the equation log(Mt1/2) = 0.57σ + 1.30, where σ represents σp for 2-substituents and σm for 3-substituents. The acceleration of fragmentation of the hydroxylamines with increasing substituent electron-donation is consistent with the proposed mechanism, and is presumably due to stabilisation of the developing positive charge on the benzylic carbon. The extent of release of amine (t∞) also increased with increasing substituent electron-donation. These data suggest that the standard 4-nitrobenzyl carbamate trigger for nitroreductase enzyme (NTR) prodrugs can likely be improved on, by increasing the rate of fragmentation by the use of α-methyl and/or electron-donating benzyl substituents. The Royal Society of Chemistry 1999.
