Neue reaktionen der carcinogenen kohlenwasserstoffe—II

The molecular etiology and prevention of estrogen-initiated cancers

“…In BP radical cation (BP +. ), it is again C-6 that displays by far the major reactivity with nucleophiles (Blackburn et al, 1974; Caspary et al, 1973; Cavalieri and Auerbach, 1974; Cremonesi et al, 1989; Jeftic and Adams, 1970; Johnson and Calvin, 1973; Menger et al, 1976; Rochlitz, 1967; Stack et al, 1995; Wilk et al, 1966; Wilke and Girke, 1972). C-1 and C-3 follow in decreasing order (Cavalieri and Calvin, 1971, 1972; Cremonesi et al, 1989).…”

“…For example, in BP, C-6 is the position with the greatest electron density and the highest reactivity with electrophiles in the neutral molecule (Cavalieri and Calvin, 1971). In BP radical cation, C-6 has the lowest electron density and the highest reactivity with nucleophiles (Cavalieri and Auerbach, 1974; Cremonesi et al, 1989; Jeftic and Adams, 1970; Rochlitz, 1967; Wilk et al, 1966; Wilke and Girke, 1972). Therefore, the relatively low IP for BP, 7.23 eV, and charge localization at C-6 render this molecule susceptible to forming a BP radical cation with reactivity to nucleophiles.…”

Role of Radical Cations in Aromatic Hydrocarbon Carcinogenesis

“…A few of the most common representative PAH are presented in Figure 2. It is well known that PAH radical cations can be produced in chemical systems with Fe3' (35)(36)(37)(38) and iodine (35,37,(39)(40)(41)(42). Iron-containing enzymes with the metal in the higher oxidative forms (Fe3+ to Fe5") are possible oxidants in biological systems.…”

“…The strategy of double-labeling experiments can be applied because one-electron oxidation involves a substitution reaction and tritium is lost from the position participating in the covalent bond between BP and DNA. Nucleophilic trapping in chemical experiments proceeds almost exclusively at C-6 in the BP radical cation (Tables 1 and 2) (37,39,41,43,44,71,72). Indeed almost 80% of the tritium is lost from C-6 when 79 CAVALIERI AND ROGAN bControl levels of binding have been subtracted from these levels, which are presented as average ± standard error of measurement.…”

Free Radicals of Benzo(a)pyrene and Derivatives

“…The chemical reactivity of the BaP cation radical indicates that nucleophilic trapping of the cation radical occurs almost exclusively at the 6 position, which is the site of highest charge density (17,18,(21)(22)(23)(24). That the nucleophile could be DNA is indicated by covalent binding of BaP to DNA in the presence of iodine (25,26).…”