Synthesis of Mitomycin C and Decarbamoylmitomycin C N2 deoxyguanosine-adducts

Abstract

Mitomycin C (MC) and Decarbamoylmitomycin C (DMC) -a derivative of MC lacking the carbamate on C10- are DNA alkylating agents. Their cytotoxicity is attributed to their ability to generate DNA monoadducts as well as intrastrand and interstrand cross-links (ICLs). The major monoadducts generated by MC and DMC in tumor cells have opposite stereochemistry at carbon one of the guanine-mitosene bond: trans (or alpha) for MC and cis (or beta) for DMC. We hypothesize that local disruptions of DNA structure from trans or cis adducts are responsible for the different biochemical responses produced by MC and DMC. Access to DNA substrates bearing cis and trans MC/DMC lesions is essential to verify this hypothesis. Synthetic oligonucleotides bearing trans lesions can be obtained by bio-mimetic methods. However, this approach does not yield cis adducts. This report presents the first chemical synthesis of a cis mitosene DNA adduct. We also examined the stereopreference exhibited by the two drugs at the mononucleotide level by analyzing the formation of cis and trans adducts in the reaction of deoxyguanosine with MC or DMC using a variety of activation conditions. In addition, we performed Density Functional Theory calculations to evaluate the energies of these reactions. Direct alkylation under autocatalytic or bifunctional conditions yielded preferentially alpha adducts with both MC and DMC. DFT calculations showed that under bifunctional activation, the thermodynamically favored adducts are alpha, trans, for MC and beta, cis, for DMC. This suggests that the duplex DNA structure may stabilize/oriente the activated pro-drugs so that, with DMC, formation of the thermodynamically favored beta products are possible in a cellular environment.

Interdependent Sequence Selectivity and Diastereoselectivity in the Alkylation of DNA by Decarbamoylmitomycin C

“…Adducts 1 a , 2 a , 2 b , 3 a , 3 b , 4 , 5 and 6 were identified by their UV spectra, retention times and co‐elution with authentic standards synthesized previously in our laboratory …”

Isolation and Rationale for the Formation of Isomeric Decarbamoylmitomycin C-N6-deoxyadenosine Adducts in DNA

“…However, with these 24 MER oligonucleotides, the reaction was performed both at 0 and 37°C. A similar process was also followed with single stranded oligonucleotides (25)(26)(27)(28)(29)(30). In this case, the reaction was performed on 10 A 260 unit scale and the reagents (DMC and Na 2 S 2 O 4 ) were scaled accordingly.…”

“…Adducts 2a and 2b were identified by their UV spectra, retention times and co-elution with authentic standards synthesized previously in our laboratories. 27 Adducts 5a and 5b were identified by their UV, HRMS and Circular Dichroism spectra. A full description of their identification is provided in the results section.…”

Genoprotective Effects of Amifostine against Mitomycin C-induced Toxicity in Human Hepatoma Cells

“…MMC has a synergistic effect with radiotherapy through its radio sensitizing effects and targeting hypoxic cells in radiation resistant tumors [5]. As a potential alkylating agent, MMC needs a bioreductive transformation to form active species that crosslink DNA [6]. Due to the biotransformation route, metabolism of MMC may produce ROS.…”