Autoxidation and prooxidation mechanisms of Danshensu

Abstract

A hydrogen peroxide (H2O2) electrode and electron spin resonance (ESR) methods were used to continuously monitor and analyze the autoxidation and prooxidation of Danshensu in aqueous solutions with various pH values. We found that Danshensu exhibited obvious autoxidative activity in alkalescence buffer solutions (pH=8.5) and the presence of Cu2+ evidently accelerated the generation of H2O2. The primary product of the autoxidation was a superoxide anion radical (O2 -•) and then it could be converted into H2O2. The autoxidation of Danshensu was totally inhibited under weak acidic conditions (pH=6.5) and a partial prooxidation of Danshensu occurred in the presence of cupric ion. However, under physiological conditions (pH=7.4), the autoxidation of Danshensu was very slow and its prooxidation, initiated by Cu2+, was very limited. Consequently, the autoxidation and prooxidation of Danshensu cannot be completely ignored when used in clinical practice especially under alkaline body fluid conditions. © Editorial office of Acta Physico-Chimica Sinica.

采用過氧化氫電極與電子自旋共振(ESR)技術對不同pH值條件下丹參素的自氧化及Cu2+對丹參素的促氧化反應機理進行了研究.實驗結果發現:在堿性條件下(pH=8.5),丹參素自氧化作用異常顯著,氧化首先生成O2-·,隨后可歧化為H2O2,并且Cu2+對H2O2信號增強也起著顯著的促進作用;在弱酸性條件下(pH=6.5),丹參素自氧化過程受到抑制,主要表現為少許Cu2+的促氧化作用;而在生理條件下(pH=7.4),丹參素的自氧化過程緩慢,有少量H2O2生成,并且Cu2+的促氧化作用非常有限.因此,當丹參素作為一種高效抗氧化劑藥用時,其自身的自氧化與金屬離子促氧化作用都應有所考慮,尤其在偏堿性體液中,更易產生大量的超氧陰離子自由基,并對生物機體造成某種損害.