Dark and photochemical interactions of dimethyltetrahydrobenzoangelicin with DNA.
A study of dark interaction and photoreaction between 4,6-dimethyltetrahydrobenzoangelicin (THBA) and DNA is described. 4,6-Dimethyltetrahydrobenzoangelicin is a furocoumarin derivative in which 4' and 5' carbons are linked by a four-methylene bridge. In spite of the bulky aliphatic ring, THBA forms a complex with DNA in the dark and, on UVA irradiation, reacts with pyrimidine bases of DNA yielding monoadducts only involving its furan side double bond. Two main photoproducts form: they derive from a C4-cycloaddition to thymine and cytosine, respectively, and account for 56% and 39% of the total photoreaction yield. Both show cis-syn configuration. Two other isomers, one with thymine and one with cytosine, formed with so much lower yield (ca 3 and 1%, respectively) that their structure could not be assigned. Furthermore, in spite of its angular structure, THBA induces a small number of crosslinks in DNA.
Miolo
G
G
Department of Pharmaceutical Sciences, University of Padova, Italy. miolo@purple.dsfarm.unipd.it
Lucchini
V
V
Vedaldi
D
D
Giuotto
A
A
Caffieri
S
S
D004247:DNA / Q000737:chemistry* / Q000528:radiation effects*; D003624:Darkness; D011564:Furocoumarins / Q000737:chemistry*; D008027:Light; D008958:Models, Molecular; D010777:Photochemistry; D012995:Solubility; D013941:Thymine / Q000737:chemistry; D014498:Uracil / Q000737:chemistry
D011564:Furocoumarins; C059470:tetrahydrobenzo-4,6-dimethylangelicin; D014498:Uracil; D004247:DNA; D013941:Thymine