4',5'-substituted methylangelicins: photocycloadducts with pyrimidine bases of DNA.
The isolation and characterization of photocycloadducts with pyrimidine bases from DNA samples irradiated (365 nm) in the presence of four 4',5'-substituted methylangelicins was performed. All these furocoumarins yielded mainly the cis-syn furan-side cycloadduct with thymine. For 4',5'-dimethyl-, 5,4',5'-trimethyl- and 6,4',5'-trimethylangelicin this adduct was accompanied by two pyrone-side adducts (cis-syn and cis-anti), whereas the 4,4',5'-trimethyl derivative gave the furan-side adduct with cytosine. The characterization of the regio- and stereochemistry of the adducts was accomplished by 1H NOE (nuclear Overhauser effect) and 1H-13C HMBC (heteronuclear multiple-bond connectivity) spectroscopies. The formation of different cycloadducts in DNA by the various derivatives highlights the role of the methyl groups in determining the regio- and stereochemistry of the cycloaddition.
Miolo
G
G
Department of Pharmaceutical Sciences, University of Padua, Italy.
Lucchini
V
V
Rodighiero
P
P
Dall'Acqua
F
F
Caffieri
S
S
D000818:Animals; D004247:DNA / Q000737:chemistry / Q000528:radiation effects*; D011564:Furocoumarins / Q000737:chemistry* / Q000494:pharmacology; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D008958:Models, Molecular; D010777:Photochemistry; D010778:Photochemotherapy; D017319:Photosensitizing Agents / Q000737:chemistry / Q000494:pharmacology; D011743:Pyrimidines / Q000737:chemistry / Q000528:radiation effects; D013237:Stereoisomerism
D011564:Furocoumarins; D017319:Photosensitizing Agents; D011743:Pyrimidines; D004247:DNA; C011659:angelicin