SYNTHESIS OF OLIGONUCLEOTIDE ADDUCTS OF THE BAY-REGION DIOL EPOXIDE METABOLITES OF CARCINOGENIC POLYCYCLIC AROMATIC-HYDROCARBONS

An efficient method for the site-specific synthesis of adducts between the biologically active diol epoxide metabolites of carcinogenic poly cyclic aromatic hydrocarbons (PAHs) and oligonucleotides in which a PA H component of predetermined stereochemistry is linked covalently to t he exocyclic amino groups of deoxyadenosine (dA) and deoxyguanosine (d G) is described. The synthetic strategy involves in the key step coupl ing a protected halopurine derivative with an amino derivative (or an aminotriol derivative) of the PAH. This method was initially employed to prepare the dA and dG adducts of the model PAH 1-methylpyrene. The appropriately protected dA adduct was then incorporated into the oligo nucleotide sequence d(GCAGGTCA()AGAG) where A(*) represents N6-pyreny lmethyl-dA. This methodology was extended to the synthesis of trans ad ducts of anti-diol epoxide metabolites of benzo[a]pyrene and 5-methylc hrysene linked to the 6-amino function of dA. The parent hydrocarbons are widespread environmental carcinogens. This synthetic approach, dub bed the total synthesis method, complements the direct synthesis metho d which involves the direct reaction of PAH diol epoxides with oligonu cleotides. The total synthesis method is broader in scope than the lat ter, and it is readily adaptable to the large scale preparation of PAH -oligonucleotide adducts required for structure determination by high resolution NMR and X-ray crystallographic techniques.