活性氧与防御酶对辣椒红素稳定性的影响

The Stability of Capsicum Pigment Treated with Reactive Oxygen Species and Defense Enzyme

目的：探讨抗氧化系统与辣椒红色素褪变的关系,为防控病理因素导致的辣椒红素损失提供理论依据。方法：采用外源活性氧·OH、H2O2、O2·-以及过氧化物酶（POD）、过氧化氢酶（CAT）和脂氧合酶（LOX）作用辣椒红素,探究其稳定性变化。结果：在外源活性氧条件下辣椒红色素不稳定。超氧阴离子（O2-·）释放源——甲基紫精在低浓度（0.8 mmol/L）作用5 h后,色素降解明显,色素溶液由红色褪变成浅黄,且浓度越高色素颜色变化越显著（P〈0.05）;辣椒红色素在过氧化氢（H2O2）环境下不稳定,8 mmol/L H2O2处理5 h后辣椒红色素残存率仅52.76%;羟自由基（·OH）比H2O2对辣椒红色素降解作用更为显著（P〈0.05）。在外源活性氧（H2O2）处理的同时添加外源防御酶POD和CAT,辣椒红色素含量降低不明显,活性氧与防御酶共存体系色素褪变较单一活性氧体系缓慢（P〉0.05）。LOX粗酶液单独作用5h后,色素溶液澄清颜色褪变明显,且LOX浓度越高,色素的降解程度越明显。作用1~5 h,LOX处理组色素含量明显低于对照组（P〈0.05）,说明LOX对色素降解有重要影响。结论：辣椒红色素褪变与辣椒抗氧化系统有着密切的关系,有效控制辣椒采后病菌感染对保护辣椒色素稳定性具有重要意义。

Objective： It could provide a basis of how to be protection of pigment loss from pathologies via discussing the relations between the change of antioxidant system in the discoloration process in the capsicum. Methods： The stability of capsicum pigment under these conditions of exogenous reactive oxygen species ·OH、 H2 O2 and peroxidase, catalase and lipoxygenase was investigated. Results： It shows that the pigment has bad resistance to exogenous ROS. As a generator of superoxide anion（O2-·）, methyl viologen at low concentration（0.8 mmol/L） in the 5 hours markedly degrade the pigment and the color of pigment solution fades from red to pale yellow. The higher concentration of the methyl viologen, the pigment color fades more significantly（P0.05）. Capsicum pigment is unstable under exogenous H2 O2. The retention ratio of capsicum pigment is only 52.76% at 8mmol/L in the 5 hours. The color degradation is more significant to capsicum pigment from ·OH than H2 O2（P0.05）. Exogenous H2 O2 ＋POD or H2 O2 ＋CAT treatment could reduce the content of pigment but not significantly. The pigment fades slower in the coexisting system of active oxygen and defense enzymes than a single active oxygen system（P0.05）. The pigment solution changes clear and fades obviously treated with LOX alone within 5 hours. And the higher concentration of LOX, the more significantly the pigment color fades. At 1~5 h, the content of capsicum pigment treated by LOX is lower obvious than the control one and it illustrates LOX has a very significant impact on the degradation of pigment. Conclusion： Experiments shows that the fading of capsicum has a close relationship with antioxidant system in capsicum. It has implications for the protection of pigment stability from strains in the pepper.