Reactivity of antineoplastic drugs with model peptides studied by advanced mass spectrometry methodologies

The in vivo interaction of the antineoplastic drug 1-3-bis-(2-chloroethyl)-1-nitrosourea (BCNU) and acrolein with model peptides has been investigated in order to provide a detailed description of their electrophilic reactivity towards biological macremolecules. Following incubation with these substances, the modified species were separated by HPLC and identified by fast atom bombardment mass spectrometry, whereas the reactive amino acids within the peptides structure were assigned by tandem mass spectrometry. Incubation with BCNU led essentially to the formation of an N-terminal carbamoil-derivative that slowly decomposed to form three isomeric structures and a very minor ethylated adduct. Alkylation with acrolein gives rise to a mixture of different adducts due to the reaction of both the double bond and the carbonyl group. Two species containing intramolecular cross-links were also observed. These results constitute the pre-requisite for in vitro and in vivo studies on the modification of hemoglobin in patients following treatment with antineoplastic drugs.