Kinetics for singlet oxygen formation by riboflavin photosensitization and the reaction between riboflavin and singlet oxygen
Kinetics for singlet oxygen formation by riboflavin photosensitization and the reaction between riboflavin and singlet oxygen
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DOI：
10.1111/j.1365-2621.2004.tb09924.x
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发表时间：
2004-11-01
影响因子：
3.9
通讯作者：
Min, DB
中科院分区：
文献类型：
--
作者：
Huang, R;Choe, E;Min, DB
测定了核黄素在光照下形成单线态氧以及核黄素在水溶液中光降解的动力学和机理。核黄素的单线态氧形成速率为2.31摩尔氧气/毫升，顶空/小时血清瓶。光照24 h后，核黄素在D2O中的降解率为66%，在H2O中的降解率为40%，说明光下单线态氧参与了核黄素的降解。用0 mM和160 mM抗坏血酸光照96h，核黄素的破坏率分别为94.0%和15.7%，核黄素与单线态氧的反应速率为1.01×10(10)/M/S，为扩散控制反应速率。这解释了在光照下食物中核黄素的极快降解。抗坏血酸和叠氮化钠在光照下以不同的猝灭机制抑制核黄素的降解。抗坏血酸对单线态氧和激发三线态核黄素均有猝灭作用。叠氮化钠仅猝灭核黄素溶液中的单线态氧，猝灭速率为1.547×10(7)/M/S，光降解核黄素时，单线态氧猝灭剂不能完全保护核黄素不被降解。添加抗坏血酸可以保护暴露在阳光下的食物中的核黄素氧化。
The formation of singlet oxygen by riboflavin and the kinetics and mechanisms of riboflavin degradation in aqueous solution under light were determined. The singlet oxygen formation rate by riboflavin was 2.31 mumole oxygen/mL, headspace/h of serum bottle. The degradations of riboflavin were 66% in D2O and 40% in H2O, respectively, under light after 24 h. The results indicate that singlet oxygen is involved in riboflavin destruction under light. The riboflavin destructions were 94.0% and 15.7% with 0 mM or 160 mM ascorbic acid, respectively, under light after 96 h. The reaction rate between riboflavin and singlet oxygen was 1.01 x 10(10)/M/s, which is a diffusion-controlled reaction rate. This explains the extremely fast degradation of riboflavin in foods under light. Ascorbic acid and sodium azide reduce the degradation of riboflavin under light with different quenching mechanisms. Ascorbic acid quenched both singlet oxygen and excited triplet riboflavin. Sodium azide quenched only the singlet oxygen in riboflavin solution with a quenching rate of 1.547 x 10(7)/M/s. With the involvement of both the Type-I and Type-II mechanisms in the riboflavin degradation under light, singlet oxygen quencher alone could not protect the riboflavin from degradation completely. Addition of ascorbic acid can protect riboflavin oxidation in foods exposed to light.