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DNA damage induced by X-irradiation and reactive oxygen species and the protection against it by sinapine

Li Weiye, Li Qun, Guo Fangqing, Gu Ruiqi

Shanghai Institute of Plant Physiology,The Chinese Academy of Sciences.Shanghai 200032

Abstract

Base damage and strand break of calf thymus DNA (ctDNA) were detected and quantified by ~(32)P-postlabeling assay. Both of them increased with the dose of X-ray; and the percentage of strand break increased more sharply than base modification. DMSO(1 mol/L) drastically decreased the percentage of strand break but had very little effect against this base damage. This suggests that the strand break caused by X-irradiation resulted from ·OH produced in an indirect reaction, while the bases were damaged by electron transfer via direct reactin or by hydrogen or aquo electron via indirect reaction. Sinapine, which has no damage to ctDNA, can protect DNA against base damage and strand scissions of X-ray. In the ·OH producing system, the effect of damage-inducing of Cu~(2+) is greater than that of Fe~(2+). Sinapine also decrease the damage induced by ·OH. This result indicates that sinapine is also a strong antioxidant.

Key words: Radiation;Reactive oxygen;Species sinapine;DNA;Damage;Protectin

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Citing This Article：

Li Weiye, Li Qun, Guo Fangqing, Gu Ruiqi. DNA damage induced by X-irradiation and reactive oxygen species and the protection against it by sinapine. Acta Physiol Sin 1997; 49 (4): (in Chinese with English abstract).