Development of Novel Quinone Phosphorodiamidate Prodrugs Targeted to DT-Diaphorase
摘要:
A series of naphthoquinone and benzimidazolequinone phosphorodiamidates has been synthesized and studied as potential cytotoxic prodrugs activated by DT-diaphorase. Reduction of the quinone moiety in the target compounds was expected to provide a pathway for expulsion of the phosphoramide mustard alkylating agent. All of the compounds synthesized were excellent substrates for purified human DT-diaphorase (k(cat)/K-m = 3 x 10(7) - 3 x 10(8) M-1 s(-1)). The naphthoquinones were toxic to both HT-29 and BE human colon cancer cell lines in a clonogenic assay; however, cytotoxicity did not correlate with DT-diaphorase activity in these cell lines. The benzimidazolequinone analogues were 1-2 orders of magnitude less cytotoxic than the naphthoquinone analogues. Chemical reduction of the naphthoquinone led to rapid expulsion of the phosphorodiamidate anion; in contrast, the benzimidazole reduction product was stable. Michael addition of glutathione and other sulfur nucleophiles provides an alternate mechanism for activation of the naphthoquinone phosphorodiamidates, and this mechanism may contribute to the cytotoxicity of these compounds.
Development of Novel Quinone Phosphorodiamidate Prodrugs Targeted to DT-Diaphorase
摘要:
A series of naphthoquinone and benzimidazolequinone phosphorodiamidates has been synthesized and studied as potential cytotoxic prodrugs activated by DT-diaphorase. Reduction of the quinone moiety in the target compounds was expected to provide a pathway for expulsion of the phosphoramide mustard alkylating agent. All of the compounds synthesized were excellent substrates for purified human DT-diaphorase (k(cat)/K-m = 3 x 10(7) - 3 x 10(8) M-1 s(-1)). The naphthoquinones were toxic to both HT-29 and BE human colon cancer cell lines in a clonogenic assay; however, cytotoxicity did not correlate with DT-diaphorase activity in these cell lines. The benzimidazolequinone analogues were 1-2 orders of magnitude less cytotoxic than the naphthoquinone analogues. Chemical reduction of the naphthoquinone led to rapid expulsion of the phosphorodiamidate anion; in contrast, the benzimidazole reduction product was stable. Michael addition of glutathione and other sulfur nucleophiles provides an alternate mechanism for activation of the naphthoquinone phosphorodiamidates, and this mechanism may contribute to the cytotoxicity of these compounds.
Formation and fate of benzimidazole-based quinone methides. Influence of pH on quinone methide fate
作者:Edward B. Skibo
DOI:10.1021/jo00048a020
日期:1992.10
The influence of pH on quinone methide fate was assessed from a comparative hydrolytic study of benzimidazole hydroquinones and their O-methylated analogues. Elimination of a leaving group from the hydroquinones affords the carbocation or the quinone methide depending on the pH. The O-methylated analogues, on the other hand, can only afford the carbocation species. Evidence is presented herein that the quinone methide species is reversibly protonated to afford the carbocation species. The acid dissociation constant for this equilibrium is pK(a) 5.5. Above pH 5.5, the quinone methide species traps both nucleophiles and the proton. Below pH 5.5, the quinone methide species is protonated to afford the carbocation species, which exclusively traps nucleophiles. Therefore, the carbocation acid dissociation constant can be used to predict quinone methide fate as a function of pH.
Development of Novel Quinone Phosphorodiamidate Prodrugs Targeted to DT-Diaphorase
作者:Carolee Flader、Jiwen Liu、Richard F. Borch
DOI:10.1021/jm000179o
日期:2000.8.1
A series of naphthoquinone and benzimidazolequinone phosphorodiamidates has been synthesized and studied as potential cytotoxic prodrugs activated by DT-diaphorase. Reduction of the quinone moiety in the target compounds was expected to provide a pathway for expulsion of the phosphoramide mustard alkylating agent. All of the compounds synthesized were excellent substrates for purified human DT-diaphorase (k(cat)/K-m = 3 x 10(7) - 3 x 10(8) M-1 s(-1)). The naphthoquinones were toxic to both HT-29 and BE human colon cancer cell lines in a clonogenic assay; however, cytotoxicity did not correlate with DT-diaphorase activity in these cell lines. The benzimidazolequinone analogues were 1-2 orders of magnitude less cytotoxic than the naphthoquinone analogues. Chemical reduction of the naphthoquinone led to rapid expulsion of the phosphorodiamidate anion; in contrast, the benzimidazole reduction product was stable. Michael addition of glutathione and other sulfur nucleophiles provides an alternate mechanism for activation of the naphthoquinone phosphorodiamidates, and this mechanism may contribute to the cytotoxicity of these compounds.