Voltammetric and Differential Pulse Stripping Study of Adenine on a Sol‐gel Derived Carbon Composite Electrode

This communication reports on the electrochemical investigation of adenine on a sol‐gel carbon composite electrode (CCE). Cyclic voltammetric (CV) technique is used to characterize the redox behavior of adenine at CCE. The peak current and peak potentials are dependent on the pH of the buffer solution. From the scan rate and peak current study, there is evidence of adsorption of adenine on the CCE. The parameters affecting the differential pulse stripping adsorption peak were systematically optimized. Under optimum conditions of E_acc=?0.10 and t_acc=60 s, a linear calibration plot was obtained, 2×10^?7–1×10^?6 M. This CCE is useful for the simultaneous analysis of adenine and guanine from denatured DNA.     

SnCl4 versus TiCl4-mediated coupling between N-6-benzoyladenine and perbenzoylated 2-deoxypyranose: Application to the synthesis of certain homochiral acyclo and carboacyclonucleosides

1,3,4-tri- -benzoyl 2-deoxyribopyranose and persilylated N-6-benzoyladenine react in two different and regioselective ways according to the nature of the coupling reagent SnCl₄ or TiCl₄. The former Lewis acid gives rise to the anomeric mixture of N-9 nucleosides and the latter affords mainly 3′-deoxy 3′-(N-6-benzoyl-9-adenyl) glycals. These two series of derivatives constitute useful synthons for the preparation of homochiral acyclo and carboacyclonucleosides.     

Simultaneous determination of guanine and adenine in DNA using an electrochemically pretreated glassy carbon electrode

A simple and reliable method based on adsorptive stripping at an electrochemically pretreated glassy carbon electrode (GCE) was proposed for simultaneous or individual determination of guanine and adenine in DNA. The detection sensitivity of guanine and adenine was improved greatly by activating the GCE electrochemically. After accumulation on pretreated GCE at open circuit for 5 min or at the potential of +0.3 V for 120 s, guanine and adenine produced well-defined oxidation peaks at about +0.8 and +1.1 V, respectively in pH 5 phosphate buffer. The detection limit for individual measurement of guanine and adenine was 4.5 ng ml⁻¹ (3×10⁻⁸ mol l⁻¹) and 4 ng ml⁻¹ (3×10⁻⁸ mol l⁻¹), respectively. Acid-denatured DNA showed two oxidation peaks corresponding to guanine and adenine residues in the same buffer. The proposed method can be used to estimate the guanine and adenine contents in DNA with good selectivity in a linear range of 0.25-5 μg ml⁻¹.     

La(OH)_3纳米片修饰玻碳电极对鸟嘌呤和腺嘌呤的电催化氧化

以La(OH)3纳米片为修饰剂,制备了基于La(OH)3纳米片修饰玻碳电极(LNP/GCE)。采用循环伏安(CV)法研究了鸟嘌呤(G)和腺嘌呤(A)在该修饰电极上的电化学行为。实验结果表明,在HAc-NaAc缓冲溶液中,该修饰电极对G和A都表现出了良好的电催化性能。在最佳条件下,用差分脉冲伏安(DPV)法对G和A进行了测定,其氧化峰电流与G和A的浓度在0.1~10μmol/L范围内呈良好的线性关系,检测限(S/N=3)分别为0.01μmol/L和0.03μmol/L。将该修饰电极用于DNA中A和G的同时测定,获得较好结果。     

Adenine as aminocatalyst for green synthesis of diastereoselective Mannich products in aqueous medium

The three-component organocatalysed Mannich type reaction is carried out in a green co-solvent of ethanol and water at room temperature using adenine as catalyst and hydrogen peroxide as additive. The Mannich products are obtained in considerably good diastereoselectivity depending on the effects of substituents on aniline.     

Spectroscopic and potentiometric studies of the interaction of adenine with trivalent metal ions

Potentiometric titration was used to determine the potentiometric diagrams of complexes of adenine with Al³⁺, Cr³⁺, and Fe³⁺. IR and Raman spectra of solids show that the interaction of adenine with Cr³⁺ is not as strong as the other metals. Fe³⁺ binds to adenine at low and medium pH values at an Fe³⁺–adenine ratio of 6, while Al³⁺ binds to adenine at all pH values at an Al³⁺–adenine ratio of 8. The IR band associated with N-9–H is split into two components at high and low wavenumbers; IR band splitting has been observed for groups with a large dipole moment such as carbonyl and phosphate. To the best of our knowledge, this is the first time to see the splitting of IR bands involving a nitrogen. We also obtained potentiometric titration plots for adenine with Al³⁺, Cr³⁺, and Fe³⁺, independently, in various molar ratios which showed an interaction with adenine, consistent with the IR and Raman findings. Metal–adenine-hydroxo complexes were formed.     

Contemplating charge transport by modeling of DNA nucleobases based nano structures

Electrical charge transport through two basic strands Thymine and Adenine of DNA has been analyzed using jellium model approach. The FFT-2D computations have been performed for semi empirical Extended Huckel Theory using Atomistix Tool kit to contemplate the charge transport metrics like current and conductance. We have scrutinized the behavior of the devices in the range of -2 V–2 V for a step size of 0.2 V. A prominent observation is the drop in HLGs of Adenine and Thymine, when working as device as compared to their intrinsic values and this is comparative more visible in case of Adenine. The current in the thymine based device exhibit linear increase with voltage in spite of having low conductance. Further the broader transmission peaks represent the strong coupling of electrodes to the scattering molecule (Thymine). The NDR effect of Adenine based device for higher bias can be utilized in various future electronics applications.     

Rapid Determination of Adenine Arabinoside Monophosphate in Pharmaceutical Injections by Droplet Spray Ionization – Tandem Mass Spectrometry (DSI-MS/MS)

Abstract

Rapid analysis of pharmaceutical preparations is of great interest in clinical studies with benefits for identifying counterfeit drugs. In this study, droplet spray ionization tandem mass spectrometry (DSI-MS/MS) was developed for the rapid determination of adenine arabinoside monophosphate in pharmaceutical injections without complex sample pretreatment. The sample solution was loaded on the slip corner placed in front of the inlet of a mass spectrometer, and high voltage was applied to the solution to create a charged spray from the corner for MS analysis. The sample was loaded for analysis without additional sample preparation protocols, which greatly simplifies the operation. The limit of detection and limit of quantification were determined to be 2.7 and 9.1?ng/mL, respectively. The recoveries were in the range from 96% to 112%, and the calculated relative standard deviations were less than 7% for the DSI-MS/MS method. Three adenine arabinoside monophosphate pharmaceutical injection samples and a degraded sample obtained by acid treatment at 40?°C were successfully analyzed by directly dissolving and diluting the sample. Moreover, the sample-loading step required only 2?s. Together these capabilities indicate that the DSI-MS/MS is a simple and robust method and has promising applications in pharmacology studies without complicated sample pretreatment.     

Theoretical study on the hydrolytic deamination mechanism of adenosine

The hydrolytic deamination mechanism of adenosine to produce inosine was studied using density functional method on two models. One is adenine and the other is adenosine. Optimized geometries of reactants, intermediates, transition states, and products were determined at B3LYP/6-311G(d,p) level. IRC calculations were performed on the transition states to verify whether it is the real transition state that connects the corresponding intermediates. Single point calculations were carried out on the previous optimized geometries obtained during IRC calculations. Four pathways have been determined for the hydrolytic deamination of adenosine. Pathway d is the most favorable pathway. In this pathway a tetra-coordinated intermediate is formed through hydrolysis reaction, then the deamination reaction takes place, which causes the cleavage of C6–N10 bond and the creation of C=O bond. Unlike the deamination of adenine, the attacking side of water molecule has effect on the deamination of adenosine. The energy barriers of adenosine deamination are a little higher than those of adenine deamination. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.