Mass Spectrometric Characterization of Sonochemical Transformation Products of 2’‐Deoxycytidine under Aerated Conditions: Direct Observation of Hydroxyhydroperoxide and Glycol

Abstract

The present report profiles the complete ultrasound mediated transformation products of a DNA nucleoside, 2’‐deoxycytidine (dCyd), the second in this series, using high resolution mass spectrometry (UPLC−Q‐ToF‐MS). The compound, dCyd was subjected to sonolysis under four different frequencies (200, 350, 620 and 1000 kHz) at a power density of 24.5 W/ml. The extent of decomposition of dCyd follows the order 620>350>1000>200 kHz. The effect of different gases on sonolysis was also investigated. This clearly indicates the involvement of oxygen radical (O•) in the transformation reactions. The sonochemical transformation products of dCyd were analyzed using UPLC−Q‐ToF‐MS and a total of 8 products were identified and characterized. The identified products include two primary products, 5,6‐dihydro‐5‐hydroxy‐6‐hydroperoxy‐2’‐deoxycytidine (hydroxyhydroperoxide) and 5,6‐dihydro‐5,6‐dihydroxy‐2’‐deoxycytidine (glycol) which are generally difficult to identify in DNA damage studies due to their instability during the work up procedure. The structural identity of all the products was confirmed by the collisionally induced dissociation (CID) pattern. Out of the eight identified products, 5,6‐dihydroxy‐2’‐deoxycytidine, 5,6‐dihydroxy‐2’‐deoxyuridine and 5‐hydroxy‐2’‐deoxyuridine are not observed in radiolysis. The difference in product profile obtained for sonolysis and radiolysis is compared and contrasted.

Insights into the Mechanism of Hydroxyl Radical Mediated Oxidations of 2-Aminopurine: A Computational and Sonochemical Product Analysis Study

“…We were also interested in the identification of stable end products (nonradical systems originated from transients) of • OH reaction with 2AP which in turn complement the theoretical predictions of key transients. The sonochemical method has been utilized for the • OH induced chemical transformations of 2AP; sonochemical reactions are considered as one of the effective methods for the production of transformation products of • OH reactions with DNA model compounds. , End product(s) analyses have been carried out by means of the liquid chromatography-quadrupole time-of-flight-tandem mass spectrometry (LC-Q-TOF-MS/MS) profiling technique. The present study (a) offers insights into the mechanism of • OH reaction with 2AP and (b) supplements the comparative study of the chemistry of oxidizing radicals with nucleic acid bases and their analogues.…”

Biphotonic Ionization of DNA: From Model Studies to Cell

“…Firstly, the hydration of occurs at both C5 and C6 of the pyrimidine ring in a ratio of about 1 to 2 based on [ 18 O]‐labeling experiments . Secondly, the 5,6‐hydroxyhydroperoxides of dCyd are not stable in aqueous solution although they have been tentatively identified from the sonolysis of dCyd in aqueous oxygenated solutions . Thirdly, deprotonation of occurs at both the exocyclic amino group and the C1′ anomeric position of the nucleoside.…”