The antioxidant system in Olea europaea to enhanced UV-B radiation also depends on flavonoids and secoiridoids
The antioxidant system in Olea europaea to enhanced UV-B radiation also depends on flavonoids and secoiridoids
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DOI：
10.1016/j.phytochem.2019.112199
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发表时间：
2020-02-01
期刊：
影响因子：
3.8
通讯作者：
Silva, Artur M. S.
中科院分区：
文献类型：
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作者：
Dias, Maria Celeste;Pinto, Diana C. G. A.;Silva, Artur M. S.
地中海作物油橄榄经常暴露在高紫外线-B辐射条件下。为了了解该物种如何在高UV-B辐射下调节其酶和非酶抗氧化系统，年轻O。将欧洲山羊豆植物（栽培品种“Galega Vulgar”）暴露于UV-B辐射（6.5 kJ m（-2）d（-1）和12.4 kJ m（-2）d（-1））五天。我们的数据表明，紫外线剂量略有不同的抗氧化保护机制的调制。特别是，超氧化物歧化酶（SOD），愈创木酚过氧化物酶（GPox）和过氧化氢酶（CAT）的活动增加，有助于H2 O2的稳态，更高的UV-B剂量的征求。此外，谷胱甘肽还原酶（Gr）活性、抗坏血酸（阿萨）和还原型谷胱甘肽（GSH）库在最高剂量下尤其增加，表明该剂量下抗氧化系统的动员更高。利用超高效液相色谱-质谱联用技术分析了该品种叶片的代谢产物，发现毛蕊花苷含量较高，其次是橄榄苦苷和木犀草素-7-O-葡萄糖苷。两种UV-B处理主要影响含量较低的类黄酮（减少4 '-甲氧基毛地黄黄酮和4'或3 '-甲氧基毛地黄黄酮葡萄糖苷）和羟基肉桂酸衍生物（HCAds，增加β-羟基毛蕊花糖苷）。这些变化不仅显示了不同的动员与紫外线强度，但也加强了第一次的保护作用，这些次要的化合物对紫外线-B，作为活性氧（ROS）清除剂和紫外线-B的盾牌，在补充与其他抗氧化系统（如阿萨/GSH循环），特别是对于高UV-B剂量。裂环烯醚萜类化合物对两种UV-B剂量的反应也很突出，橄榄苦苷减少，2“-甲氧基橄榄苦苷增加。由于橄榄苦苷含量丰富，因此开环环烯醚萜类化合物在O. europaea保护免受UV-B，可能通过充当信号分子和ROS清除剂。这是首次报道了UV-B辐射对裂环烯醚萜类橄榄苦苷的影响，并为该化合物在O.抗氧化防御机制。
The Mediterranean crop Olea europaea is often exposed to high UV-B irradiation conditions. To understand how this species modulates its enzymatic and non-enzymatic antioxidant system under high UV-B radiation, young O. europaea plants (cultivar "Galega Vulgar") were exposed, for five days, to UV-B radiation (6.5 kJ m(-2) d(-1) and 12.4 kJ m(-2) d(-1)). Our data indicate that UV-doses slightly differ in the modulation of the antioxidant protective mechanisms. Particularly, superoxide dismutase (SOD), guaiacol peroxidase (GPox) and catalase (CAT) activities increased contributing to H2O2 homeostasis, being more solicited by higher UV-B doses. Also, glutathione reductase (Gr) activity, ascorbate (AsA) and reduced glutathione (GSH) pools increased particularly under the highest dose, suggesting a higher mobilization of the antioxidant system in this dose. The leaf metabolites' profile of this cultivar was analysed by UHPLC-MS. Interestingly, high levels of verbascoside were found, followed by oleuropein and luteolin-7-O-glucoside. Both UV-B treatments affected mostly less abundant flavonoids (decreasing 4'-methoxy luteolin and 4' or 3'-methoxy luteolin glucoside) and hydroxycinnamic acid derivatives (HCAds, increasing beta-hydroxyverbascoside). These changes show not only different mobilization with the UV-intensity, but also reinforce for the first time the protective roles of these minor compounds against UV-B, as reactive oxygen species (ROS) scavengers and UV-B shields, in complement with other antioxidant systems (e.g. AsA/GSH cycle), particularly for high UV-B doses. Secoiridoids also standout in the response to both UV-B doses, with decreases of oleuropein and increases 2 ''-methoxyoleuropein. Being oleuropein an abundant compound, data suggest that secoiridoids play a more important role than flavonoids and HCAds, in O. europaea protection against UV-B, possibly by acting as signalling molecules and ROS scavengers. This is the first report on the influence of UV-B radiation on the secoiridoid oleuropein, and provides a novel insight to the role of this compound in the O. europaea antioxidant defence mechanisms.