Roca María, Pérez-Gálvez Antonio
Food Phytochemistry Department, Instituto de la Grasa (CSIC), University Campus, Building 46, 41013 Sevilla, Spain.
J Nat Prod. 2020 Apr 24;83(4):873-880. doi: 10.1021/acs.jnatprod.9b00546. Epub 2020 Mar 5.
Despite the fact that chlorophyll degradation is a physiological phenomenon occurring daily in all photosynthetic tissues, chlorophyll catabolites are not fully identified. Three new forms (, , and ) of linear chlorophyll catabolites (phyllobilins) have been characterized in senescent leaves of with spectroscopic data. Compound is a hypermodified blue fluorescent chlorophyll catabolite (FCC) esterified with the potent antioxidant hydroxytyrosol. The sequestration of this phenol by a chlorophyll catabolite could explain the physiological meaning of the persistence of FCCs in some senescent plants. Compound , a yellow chlorophyll catabolite (YCC) originated from the oxidation at C-15 of . YCCs have been identified previously and are exclusively formed in the plant vacuole from the final nonfluorescent chlorophyll catabolites (NCCs). The presence of in leaves implies a new reaction in chlorophyll catabolism, as the characterization of implies that YCCs can be also be oxidized in the cytosol from FCCs. Finally, phyllobilin represents a new type of YCC characterized by an inflexible bicyclo glucosyl moiety linked through an intramolecular esterification of the propionic acid residue with the C-3 hydroxy group. The corresponding NCC precursor was recently identified and now the characterization of shows that even this rigid structure can be further oxidized. Undoubtedly, the characterization of phyllobilins is essential to completely comprehend chlorophyll degradation.
尽管叶绿素降解是所有光合组织中每天都会发生的一种生理现象，但叶绿素分解产物尚未得到完全鉴定。利用光谱数据，在衰老的拟南芥叶片中对三种新形式（、和）的线性叶绿素分解产物（叶卟啉）进行了表征。化合物是一种高度修饰的蓝色荧光叶绿素分解产物（FCC），与强效抗氧化剂羟基酪醇酯化。叶绿素分解产物对这种酚的螯合可以解释FCCs在一些衰老植物中持续存在的生理意义。化合物是一种黄色叶绿素分解产物（YCC），由在C-15处氧化产生。YCCs此前已被鉴定，并且仅在植物液泡中由最终的非荧光叶绿素分解产物（NCCs）形成。叶片中的存在意味着叶绿素分解代谢中有新的反应，因为的表征表明YCCs也可以在细胞质中由FCCs氧化产生。最后，叶卟啉代表了一种新型的YCC，其特征是通过丙酸残基与C-3羟基的分子内酯化连接的刚性双环葡糖基部分。相应的NCC前体最近已被鉴定出来，现在的表征表明，即使是这种刚性结构也可以进一步氧化。毫无疑问，叶卟啉的表征对于完全理解叶绿素降解至关重要。
