DNA‐Triggered Enhancement of Singlet Oxygen Production by Pyridinium Alkynylanthracenes. Issue 54 (14th August 2021)

• Record Type: Journal Article
• Authors: Fudickar, Werner; Bauch, Marcel; Ihmels, Heiko; Linker, Torsten
• Is Part Of: Chemistry. Volume 27:Issue 54(2021)
• Page Start: 13591
• Page End: 13604
• Publication Date: 2021-08-14
• Subjects: Anthracene -- DNA -- intercalations -- photochemistry -- singlet oxygen; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.202101918
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: There is an ongoing interest in 1 O2 sensitizers, whose activity is selectively controlled by their interaction with DNA. To this end, we synthesized three isomeric pyridinium alkynylanthracenes 2 o – p and a water‐soluble trapping reagent for 1 O2 . In water and in the absence of DNA, these dyes show a poor efficiency to sensitize the photooxygenation of the trapping reagent as they decompose due to electron transfer processes. In contrast, in the presence of DNA 1 O2 is generated from the excited DNA‐bound ligand. The interactions of 2 o – p with DNA were investigated by thermal DNA melting studies, UV/vis and fluorescence spectroscopy, and linear and circular dichroism spectroscopy. Our studies revealed an intercalative binding with an orientation of the long pyridyl‐alkynyl axis parallel to the main axis of the DNA base pairs. In the presence of poly(dA : dT), all three isomers show an enhanced formation of singlet oxygen, as indicated by the reaction of the latter with the trapping reagent. With green light irradiation of isomer 2 o in poly(dA : dT), the conversion rate of the trapping reagent is enhanced by a factor >10. The formation of 1 O2 was confirmed by control experiments under anaerobic conditions, in deuterated solvents, or by addition of 1 O2 quenchers. When bound to poly(dG : dC), the opposite effect was observed only for isomers 2 o and 2 m, namely the trapping reagent reacted significantly slower. Overall, we showed that pyridinium alkynylanthracenes are very useful intercalators, that exhibit an enhanced photochemical 1 O2 generation in the DNA‐bound state. Abstract : New pyridinium alkynylanthracenes are capable to generate singlet oxygen upon irradiation with green light only, when bound to polynucleotides by intercalation, whereas they slowly decompose when irradiated in water showing poor sensitization activity. Enhanced sensitization activity is observed upon interaction with AT but not GC base pairs. This makes them interesting for applications, where singlet oxygen has to be generated with local control.