Effects of ultrasound on nucleic acid bases

Abstract

To understand the effects of ultrasound in biological systems at the molecular level, sonolysis of nucleic acid bases at sonic intensities less than or equal to 5 W/cm2 was studied. These sonoreactions were followed by UV-spectral decrease and by sonoproduct analysis. The order of reactivity was found to be thymine greater than uracil greater than cytosine greater than guanine greater than adenine. The extent of sonoreactions depends on the exposure time and the rate of the intensity. Aeration was necessary for maintenance of a reasonable reaction rate. "Threshold" intensities for uracil and thymine were observed at approximately 0.5 W/cm2. The effectiveness of the dissolved gases in producing sonoreactions was Ar greater than 02 greater than air greater than N2 greater than He greater than N2O, suggestive of free radicals mediating these reactions since N2O is an effective radical scavenger. Studies of the effects of substituents have shown that electronic rather than steric effects may have a greater influence. Preliminary identification indicates that cis- and trans-uracil glycols are the major products of uracil. Thus, a stepwise mechanism of pyrimidine sonolysis is proposed. Sonolysis of a dilute aqueous solution of uracil yielded pseudo-first-order kinetics in terms of [Ura] with a rate constant of 3.9 X 10(-2) min-1, implying that the rate-limiting step is the reaction of HO- with the base.

The sonolysis of cytosine and thymine

“…Ultrasonically induced chemical reactions of biologically important molecules related to RNA and DNA have been reported previously (1)(2)(3)(4). 2 In this paper we report the results of the sonolytic degradation of the pyrimidine bases cytosine and thymine.…”

“…These adducts may undergo disproportionation reaction to produce cytosine and cytosine glycols. The uracil glycols (5) can be formed by the deamination of cytosine glycols (4). The remaining products may occur as follows: isobarbituric acid (6) derives from uracil cis-glycol by loss of a water molecule; alloxan monohydrate (9) may result from hydration of alloxan (lo), which is derived from uracil glycols (5) by loss of H2.…”

Enzymatic Assisted Ultrasonic Pretreatment’s Effect on Poplar Pulp Properties

“…It has been proposed that the ultrasound-assisted reactions in aqueous solutions involve free-radical mechanisms because of the formation of hydroxyl radicals (HO·) with oxidation capabilities (Weissler 1959(Weissler , 1962Anbar and Pecht 1964;Reifsneider and Spurlock 1973;Mead et al 1975;McKee et al 1977). These proposals of free-radical formation have been confirmed via spin-trapping techniques (Makino et al 1982(Makino et al , 1983 Enzymatic treatments have gained recognition in the pulp and papermaking industry because they are stereo specific, nontoxic, environment friendly, and energy conserving alternatives (Madhu and Chakraborty 2017).…”

The Properties and Application of an Ultrasonic-Assisted Wheat Straw Pulp having Enhanced Tendency for Ash Formation

“…The applications of this technology in the process of pulping (Healey et al 1956;Subhedar and Gogate 2014), beating, preparation of nanocrystalline cellulose (Li et al 2011) and carboxymethyl cellulose (Hivechi et al 2015), and treatment of recycled fiber (Tatsumi et al 2000;Subhedar et al 2015) have been well documented. It has been proposed that the ultrasound-assisted reactions in aqueous solutions involve free-radical mechanisms because of the formation of hydroxyl radicals (HO·) with oxidation capabilities (Weissler et al 1959(Weissler et al , 1962Anbar and Pecht 1964;McKee et al 1977;Reifsneider and Spurlock 1973;Mead et al 1975). These free-radical formations have been confirmed via spin-trapping techniques (Makino et al 1982(Makino et al , 1983.…”