TY - JOUR
T1 - Exocyclic deoxyadenosine adducts of 1,2,3,4-diepoxybutane
T2 - Synthesis, structural elucidation, and mechanistic studies
AU - Seneviratne, Uthpala
AU - Antsypovich, Sergey
AU - Goggin, Melissa
AU - Dorr, Danae Quirk
AU - Guza, Rebecca
AU - Moser, Adam
AU - Thompson, Carrie
AU - York, Darrin M.
AU - Tretyakova, Natalia
PY - 2010/1/18
Y1 - 2010/1/18
N2 - 1,2,3,4-Diepoxybutane (DEB) is considered the ultimate carcinogenic metabolite of 1,3-butadiene, an important industrial chemical and environmental pollutant present in urban air. Although it preferentially modifies guanine within DNA, DEB induces a large number of A → T transversions, suggesting that it forms strongly mispairing lesions at adenine nucleobases. We now report the discovery of three potentially mispairing exocyclic adenine lesions of DEB: N6,N6-(2,3-dihydroxybutan-1,4-diyl)-2′- deoxyadenosine (compound 2), 1,N6-(2-hydroxy-3-hydroxymethylpropan-1, 3-diyl) -2′-deoxyadenosine (compound 3), and 1,N6-(1- hydroxymethyl-2-hydroxypropan-1,3-diyl)-2′-deoxyadenosine (compound 4). The structures and stereochemistry of the novel DEB-dA adducts were determined by a combination of UV and NMR spectroscopy, tandem mass spectrometry, and independent synthesis. We found that synthetic N6-(2-hydroxy-3,4- epoxybut-1-yl)-2′-deoxyadenosine (compound 1) representing the product of N6-adenine alkylation by DEB spontaneously cyclizes to form 3 under aqueous conditions or 2 under anhydrous conditions in the presence of an organic base. Compound 3 can be interconverted with 4 by a reversible unimolecular pericyclic reaction favoring 4 as a more thermodynamically stable product. Both 3 and 4 are present in double stranded DNA treated with DEB in vitro and in liver DNA of laboratory mice exposed to 1,3-butadiene by inhalation. We propose that in DNA under physiological conditions, DEB alkylates the N-1 position of adenine in DNA to form N1-(2-hydroxy-3,4-epoxybut-1-yl)-adenine adducts, which undergo an SN2-type intramolecular nucleophilic substitution and rearrangement to give 3 (minor) and 4 (major). Formation of exocyclic DEB-adenine lesions following exposure to 1,3-butadiene provides a possible mechanism of mutagenesis at the A:T base pairs.
AB - 1,2,3,4-Diepoxybutane (DEB) is considered the ultimate carcinogenic metabolite of 1,3-butadiene, an important industrial chemical and environmental pollutant present in urban air. Although it preferentially modifies guanine within DNA, DEB induces a large number of A → T transversions, suggesting that it forms strongly mispairing lesions at adenine nucleobases. We now report the discovery of three potentially mispairing exocyclic adenine lesions of DEB: N6,N6-(2,3-dihydroxybutan-1,4-diyl)-2′- deoxyadenosine (compound 2), 1,N6-(2-hydroxy-3-hydroxymethylpropan-1, 3-diyl) -2′-deoxyadenosine (compound 3), and 1,N6-(1- hydroxymethyl-2-hydroxypropan-1,3-diyl)-2′-deoxyadenosine (compound 4). The structures and stereochemistry of the novel DEB-dA adducts were determined by a combination of UV and NMR spectroscopy, tandem mass spectrometry, and independent synthesis. We found that synthetic N6-(2-hydroxy-3,4- epoxybut-1-yl)-2′-deoxyadenosine (compound 1) representing the product of N6-adenine alkylation by DEB spontaneously cyclizes to form 3 under aqueous conditions or 2 under anhydrous conditions in the presence of an organic base. Compound 3 can be interconverted with 4 by a reversible unimolecular pericyclic reaction favoring 4 as a more thermodynamically stable product. Both 3 and 4 are present in double stranded DNA treated with DEB in vitro and in liver DNA of laboratory mice exposed to 1,3-butadiene by inhalation. We propose that in DNA under physiological conditions, DEB alkylates the N-1 position of adenine in DNA to form N1-(2-hydroxy-3,4-epoxybut-1-yl)-adenine adducts, which undergo an SN2-type intramolecular nucleophilic substitution and rearrangement to give 3 (minor) and 4 (major). Formation of exocyclic DEB-adenine lesions following exposure to 1,3-butadiene provides a possible mechanism of mutagenesis at the A:T base pairs.
UR - http://www.scopus.com/inward/record.url?scp=75149148786&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=75149148786&partnerID=8YFLogxK
U2 - 10.1021/tx900312e
DO - 10.1021/tx900312e
M3 - Article
C2 - 19883087
AN - SCOPUS:75149148786
SN - 0893-228X
VL - 23
SP - 118
EP - 133
JO - Chemical research in toxicology
JF - Chemical research in toxicology
IS - 1
ER -