Reaction of acetaldehyde with 5-aminolevulinic acid via dihydropyrazine derivative.

When a solution of 5-aminolevulinic acid (ALA) was incubated with acetaldehyde at neutral pH, a product was generated. This product was identified as 3-ethylpyrazine-2,5-dipropanoic acid (ETPY). ETPY was stable at neutral pH.

Formation of 8-S-L-cysteinylguanosine from 8-bromoguanosine and cysteine.

When 8-bromoguanosine was incubated with cysteine at pH 7.4 and 37 °C, a previously unidentified product was formed as a major product in addition to guanosine. The product was identified as a cysteine substitution derivative of guanosine at the 8 position, 8-S-L-cysteinylguanosine.

Reaction of 3',5'-di-O-acetyl-2'-deoxyguansoine with hypobromous acid.

Hypobromous acid (HOBr) is formed by eosinophil peroxidase and myeloperoxidase in the presence of H2O2, Cl(-), and Br(-) in the host defense system of humans, protecting against invading bacteria. However, the formed HOBr may cause damage to DNA and its components in the host. When a guanine nucleoside (3',5'-di-O-acetyl-2'-deoxyguansoine) was treated with HOBr at pH 7.

Effects of halides on reaction of nucleosides with ozone.

Ozone (O(3)), a major component of photochemical oxidants, is used recently as a deodorizer in living spaces. It has been reported that O(3) can directly react with DNA, causing mutagenesis in human cells and carcinogenesis in mice. However, little is known about the effects of coexistent ions in the reaction of O(3).

Effects of chloride, bromide, and iodide upon decomposition of nucleosides induced by ultrasound in neutral solution.

When the ultrasound of 42 kHz was irradiated on a neutral mixture of 2'-deoxycytidine, 2'-deoxyguanosine, 2'-deoxythymidine, and 2'-deoxyadenosine, concentrations of all the nucleosides decreased. Addition of NaCl to the system had no effect. NaBr suppressed the reactions for all the nucleosides, but the efficiency of 2'-deoxyguanosine was low.

Effects of bromide upon reaction of nucleosides with hydrogen peroxide induced by ultraviolet light.

When ultraviolet light was irradiated on a neutral solution of deoxynucleosides and hydrogen peroxide, concentrations of all the deoxynucleosides decreased greatly. Addition of bromide in the system suppressed the reactions of 2'-deoxycytidine, 2'-deoxythymidine, and 2'-deoxyadenosine, but not that of 2'-deoxyguanosine. Addition of hydroxyl radical scavengers suppressed the reaction.

Acetylation of the amino group on guanosine induced by nitric oxide in acetonitrile under aerobic conditions.

When nitric oxide was bubbled into acetonitrile under aerobic conditions, the solution showed a cobalt-blue color. Addition of guanosine into the solution generated N2-acetylguanosine as a major product. The result of the reaction using 15N labeled acetonitrile indicated that the nitrogen atom of the acetylated exocyclic amino group on N2-acetylguanosine originated from acetonitrile.

Formation of diazoate intermediate upon nitrous acid and nitric oxide treatment of 2'-deoxyadenosine.

When 2'-deoxyadenosine was treated with HNO(2) or NO, a small amount of a previously unidentified product was formed. The product was also formed by the reaction of 2'-deoxyadenosine with isoamyl nitrite in tetrahydrofuran as a major product. The product was identified as a diazoate derivative of 2'-deoxyadenosine, a reaction intermediate.

Reaction of 2'-deoxycytidine with peroxynitrite in the presence of ammonium bromide.

Peroxynitrite, a reactive nitrogen species generated from nitric oxide and superoxide anion radical, is an endogenous potential risk factor for human cancer. When 2'-deoxycytidine was incubated with peroxynitrite at neutral pH and 37 degrees C, the reaction was greatly enhanced by the addition of ammonium bromide. Both ammonium ion and bromide ion were required to exert the enhancing effect.

Effects of nitrite and nitrate on DNA damage induced by ultraviolet light.

UV light is a major cause of human skin cancers. Nitrite and nitrate are well-known potential risk factors for gastric cancer. Little attention has been paid to the relationship between UV light and nitrite or nitrate on cancer.