Photolysis of Thiopurines in the Presence of Oxygen<sup>+</sup>

Wenska, G.; Paszỳc, S.

doi:10.1515/znb-1981-1224

Cited by 10 publications

(4 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Very little is known about the photochemical behavior of the 6-thiopurine and TI, even in simple systems. Except for reports on the 6-thiopurine photooxidation 11, 12 and on the intramolecular photoaddition of the C=S group to the C(5)=C (6) bond of thymine in thymidylyl-(5¢-3¢)-2¢-deoxythioinosine dinucleotide, 7 there are, to our knowledge, no other reports on lightinduced reactions of 6-thiopurine, its riboside or any other derivative.…”

Section: Introductionmentioning

confidence: 92%

Photocycloaddition of the T1 excited state of thioinosine to uridine and adenosine

Wenska

Filipiak

Burdziński

et al. 2009

Photochem Photobiol Sci

View full text Add to dashboard Cite

Novel photoadducts were obtained by irradiation of thioinosine (6-thiopurine riboside, TI) in deaerated aqueous solution without and in the presence of uridine and adenosine. Excitation (lambda > 300 nm) of TI to its excited S2 state yields a single bimolecular photoproduct. It is a purine-pyrimidine diriboside in which the purine ring is attached to the amide nitrogen of 6-amino-4-thioxo-5-formamidopyrimidine. When TI was irradiated in the presence of an excess of adenosine, two photoproducts were isolated: diribosides of N-(4,6-diaminopirymidin-5-yl)-N-formyl-6-aminopurine and N-(4-amino-6-formylamino-pyrimidin-5-yl)-6-aminopurine, both containing a purine and a formylaminopyrimidine (Fapy) fragment. The photoreaction of TI with uridine gave two regioisomeric photoproducts identified as diribosides containing either 5- or 6-(purin-6-yl)uracil as aglycones. A multistep mechanism leading to the stable photoproducts is proposed. In the first step of the mechanism, the C=S group of the excited TI undergoes a [2 + 2] cycloaddition regioselectively to the N(7)=C(8) bond of the purine ring or adds in a non-regioselective manner to the C(5)=C(6) bond of uracil. The unstable photoproducts thus formed undergo a series of dark reactions at room temperature. The photocycloaddition reactions originate from the excited T1 state of TI. This conclusion is supported by a combination of evidence from reaction quenching studies using both steady-state quantum yield determinations and kinetics results from nanosecond laser flash photolysis. The T1 state of TI is quenched by other TI molecules in their S0 state (self-quenching) and also by uridine and adenosine, all with large rate constants (0.8-5) x 10(9) M(-1) s(-1). The quantum yields of the reactions are in general very low (phi(R) < or = 8 x 10(-3)). The sources of the inefficiency in the photocycloaddition of TI to uridine and adenosine are discussed. The photoproducts containing the Fapy residue undergo deformylation and isomerization of the ribosyl moiety (anomerization, furanose/pyranose transformation) upon heating in aqueous solution. Products of the transformations were identified.

show abstract

Section: Introductionmentioning

confidence: 92%

Photocycloaddition of the T1 excited state of thioinosine to uridine and adenosine

Wenska

Filipiak

Burdziński

et al. 2009

Photochem Photobiol Sci

View full text Add to dashboard Cite

show abstract

“…The mixtures were inseparable but stable in solid state and were tested as such. Only when the mixtures were in solution, we could see slow desulfurization take place, potentially by low amounts of peroxide formation from atmospheric oxygen under light exposure [54,55].…”

Section: -Thiobarbituric Acid 5amentioning

confidence: 94%

Investigation of Tetrasubstituted Heterocycles Reveals Hydantoins as a Promising Scaffold for Development of Novel Antimicrobials with Membranolytic Properties

et al. 2022

View full text Add to dashboard Cite

“…EtOAc-MeOH (1:1) (3:1), 9-[3-(Thym-l-yl)propyl] hypoxanthine lb was synthetized as described previously [27]. The compound la was prepared from lb by methylation (CH 3 I, NaH, DMF).…”

Section: Methodsmentioning

confidence: 99%

The Photoreactions of Thymine with Hypoxanthine and Imidazole

Wenska

1985

Zeitschrift Für Naturforschung B

Self Cite

View full text Add to dashboard Cite

Photochemical reactions of thymine linked to hypoxanthine or imidazole by a trimethylene chain were studied in aqueous solution. Irradiation (λ = 254 nm) of thymine-hypoxanthine pair yielded two internal cycloadducts with azetidine and cyclobutane part structures. Sensitization and quenching experiments suggested that the excited singlet was the reactive state in the photo-cycloaddition reactions. Only cyclobutanes were isolated from irradiated (λ = 290 nm) solutions of thymine-imidazole pairs. Photocycloadditions were reversible upon irradiation at λ = 254 nm

show abstract

Photolysis of Thiopurines in the Presence of Oxygen⁺

Cited by 10 publications

References 11 publications

Photocycloaddition of the T1 excited state of thioinosine to uridine and adenosine

Photocycloaddition of the T1 excited state of thioinosine to uridine and adenosine

Investigation of Tetrasubstituted Heterocycles Reveals Hydantoins as a Promising Scaffold for Development of Novel Antimicrobials with Membranolytic Properties

The Photoreactions of Thymine with Hypoxanthine and Imidazole

Contact Info

Product

Resources

About

Photolysis of Thiopurines in the Presence of Oxygen+

Cited by 10 publications

References 11 publications

Photocycloaddition of the T1 excited state of thioinosine to uridine and adenosine

Photocycloaddition of the T1 excited state of thioinosine to uridine and adenosine

Investigation of Tetrasubstituted Heterocycles Reveals Hydantoins as a Promising Scaffold for Development of Novel Antimicrobials with Membranolytic Properties

The Photoreactions of Thymine with Hypoxanthine and Imidazole

Contact Info

Product

Resources

About

Photolysis of Thiopurines in the Presence of Oxygen⁺