Chlorophyll Breakdown by a Biomimetic Route

Abstract

Colorless nonfluorescent chlorophyll catabolites (NCCs), the final products of endogenous chlorophyll breakdown in higher plants, were prepared by biomimetic partial synthesis from chlorophyll a. A nonstereoselective variant of the synthesis also provided an entry to the enantiomers of natural NCCs.

A novel blue fluorescent chlorophyll catabolite accumulates in senescent leaves of the peace lily and indicates a split path of chlorophyll breakdown

“…The presence of ester functions at the propionyl side chain in this 'persistent' FCC and the detection of lesser amounts of NCCs in yellow Sw-leaves, are both in line with the hypothesis on the natural transformation of FCCs to NCCs [21,22]: In senescent leaves, NCCs are indicated to result in the acidic medium of the vacuoles from a rapid stereo-selective isomerization of FCCs, which is accelerated by their free propionic acid group [4,19]. Indeed, NCCs, the non-fluorescent tetrapyrrolic 'end' products of Chlbreakdown carry a propionic acid group and are found in the vacuoles [3,29].…”

“…3). The CD-spectrum of Sw-NCC-58 was similar to that of Cj-NCC-1 [20], indicating a common configuration at C(15) and C(13 2 ) [19]. However, HPLC-analysis indicated Sw-NCC-58 and Cj-NCC-1 to be different.…”

“…Sw-FCC-62 is also a new member of the seemingly unique 'persistent' FCCs, which are resistant against their (chemical) conversion to the corresponding NCCs [19,21]. Related FCCs were found to accumulate and induce blue luminescence in yellow M. acuminata bananas [12], in senescent sections of peels of overripe bananas [14], and in senescent banana leaves [13] (see SuppMat, Fig.…”

“…5 and 6). Indeed, the remarkable ester function of the latter and the non-acidic cytosolic medium help preserve it by slowing down its 'chemical' isomerization to an NCC [19]. No evidence is available for a functionalized NCC isomeric to Sw-FCC-62 that could result from an eventual dislocation of Sw-FCC-62 into the vacuole.…”

“…S4). Signals of all 35 nonexchangeable protons of the tetrapyrrole moiety were assigned, identifying it as a functionalized FCC (see e.g., [15,19]). The complex signals of 14 additional hydrogen atoms identified a glucopyranose moiety and a 2-(3,4-dihydroxyphenyl)-ethyl unit as peripheral modification of this Sw-FCC, as well as the b-configuration at the anomeric center of the sugar unit.…”