Surjadinata Bernadeth B, Jacobo-Velázquez Daniel A, Cisneros-Zevallos Luis
Department of Horticultural Sciences, Texas A&M University, College Station, TX 778432-133, USA.
Tecnológico de Monterrey, Escuela de Ingeniería y Ciencias, Centro de Biotecnología FEMSA, Av. Eugenio Garza Sada 2501 Sur, C.P. 64849 Monterrey, N.L., Mexico.
Molecules. 2017 Apr 24;22(4):668. doi: 10.3390/molecules22040668.
Previously, we found that phenolic content and antioxidant capacity (AOX) in carrots increased with wounding intensity. It was also reported that UV radiation may trigger the phenylpropanoid metabolism in plant tissues. Here, we determined the combined effect of wounding intensity and UV radiation on phenolic compounds, AOX, and the phenylalanine ammonia-lyase (PAL) activity of carrots. Accordingly, phenolic content, AOX, and PAL activity increased in cut carrots with the duration of UVC radiation, whereas whole carrots showed no increase. Carrot pies showed a higher increase compared to slices and shreds. Phenolics, AOX, and PAL activity also increased in cut carrots exposed to UVA or UVB. The major phenolics were chlorogenic acid and its isomers, ferulic acid, and isocoumarin. The type of UV radiation affected phenolic profiles. Chlorogenic acid was induced by all UV radiations but mostly by UVB and UVC, ferulic acid was induced by all UV lights to comparable levels, while isocoumarin and 4,5-diCQA was induced mainly by UVB and UVC compared to UVA. In general, total phenolics correlated linearly with AOX for all treatments. A reactive oxygen species (ROS) mediated hypothetical mechanism explaining the synergistic effect of wounding and different UV radiation stresses on phenolics accumulation in plants is herein proposed.
此前，我们发现胡萝卜中的酚类物质含量和抗氧化能力（AOX）会随着损伤强度的增加而升高。也有报道称，紫外线辐射可能会触发植物组织中的苯丙烷代谢。在此，我们测定了损伤强度和紫外线辐射对胡萝卜酚类化合物、AOX以及苯丙氨酸解氨酶（PAL）活性的综合影响。相应地，随着UVC辐射时间的延长，切好的胡萝卜中酚类物质含量、AOX和PAL活性均有所增加，而完整的胡萝卜则没有增加。胡萝卜派相比切片和切丝表现出更高的增幅。暴露于UVA或UVB下的切好的胡萝卜中酚类物质、AOX和PAL活性也有所增加。主要的酚类物质有绿原酸及其异构体、阿魏酸和异香豆素。紫外线辐射的类型影响酚类物质的分布。所有紫外线辐射都会诱导绿原酸的产生，但主要是UVB和UVC，所有紫外线对阿魏酸的诱导水平相当，而异香豆素和4,5-二咖啡酰奎宁酸相比UVA主要由UVB和UVC诱导产生。总体而言，所有处理中总酚类物质与AOX呈线性相关。本文提出了一种活性氧（ROS）介导的假说机制，用以解释损伤和不同紫外线辐射胁迫对植物中酚类物质积累的协同作用。
