Water soluble fluorescent substances in Citrus unshiu fruit and their possible participation in chlorophyll catabolism

摘要

Changes in levels of fluorescence substances (FS) in aqueous extracts of Citrus unshiu (C. unshiu) peels were measured by the 3 -dimensional (3 - D) fluorescence spectrophotometer. FS, extracted from C. unshiu peels, have characteristic fluorescence at excitation (Ex) 320 - 330 nm and emission (Em) 420- 440 nm. Ex and Ern of FS are very similar to those of lipofucsin - like - compounds known to accumulate in tissues during aging and fluorescent -chlorophyll -catabolites (FCC) appeared to be a product of oxidative cleavage of chlorophyll (Chl)-porphyrin. The amount of FS increased in yellow -green C. unshiu peels and decreased in yellow C. unshiu peels. In ethylene- treated C. unshiu peels, the amount of ITS increased at the time of rapid disappearance of Chl, and decreased after that, whereas FS of non - treated C. unshiu peels did not change during incubation. A possible participation of FS in Chl catabolism is discussed.