Evolution in Caffeoylquinic Acid Content and Histolocalization During Coffea canephora Leaf Development

Abstract

HPLC analyses revealed that caffeoylquinic acid content was 10-fold lower in adult than in juvenile leaves. The most abundant cinnamate conjugate was 5-CQA, but dicaffeoylquinic acids (particularly in juvenile leaves) and feruloylquinic acids were also present. Using specific reagents, histochemical and microspectrofluorometrical analysis showed that caffeoylquinic acids (mono- and di-esters) were closely associated with chloroplasts in very young leaves. During leaf ageing, they were found to first accumulate intensively in specific chlorenchymatous bundle sheath cells and then in phloem sclerenchyma cells. The association with chloroplasts suggests that caffeoylquinic acids have a protective role against light damage. In older tissues, their presence in the leaf vascular system indicates that they are transported via phloem and confirms their involvement in lignification processes. In accordance with the hypothesis of a complex formation with caffeine, similar tissue distribution was observed for alkaloids and this is further discussed.

Immunohistochemical localization of caffeine in young Camellia sinensis (L.) O. Kuntze (tea) leaves

“…canephora leaves (Mondolot et al 2006). Literature has suggested the localization of alkaloids in the vascular area, i.e.…”

“…Literature has suggested the localization of alkaloids in the vascular area, i.e. caffeine in C. canephora leaves was suggested to be localized to the phloem cells (Mondolot et al 2006), swainsonine was determined to be in the phloem of Astragalus lentiginosus (locoweed) (Dreyer et al 1985) and with regards to the xylem, tropane 20 alkaloids were localized in the xylem cells of roots of Duboisia myoporoides (Khanam et al 2000) or that quinolizidine alkaloids were located in the xylem of the Lupinus albus (White Lupin) (Bäumel et al 1995). This localization probably functions as a chemical defense protecting the plant from sap sucking insects such as aphids (Dreyer et al 1985).…”

“…Caffeine has been suggested to form complexes with chlorogenic acid (a caffeoylquinic acid) (Spencer et al 1988;Mösli Waldhauser and Baumann 1996;Mondolot et al 2006). Mondolot et al (2006) works were performed on Coffea canephora leaf development and it was determined that caffeine was present within phloem cells in association with caffeoylquinic acids and most likely chlorogenic acid due to the compound being in very high concentrations in young leaves. Mondolot's localization of caffeine confirms our results, and it is most likely that caffeine is also in association with chlorogenic acid within the precursor phloem of young C. sinensis leaves.…”

“…Mondolot's localization of caffeine confirms our results, and it is most likely that caffeine is also in association with chlorogenic acid within the precursor phloem of young C. sinensis leaves. This does need confirmation and can be confirmed by microscopy using Neu's reagent (Neu 1957) and viewed using UV light and observe for a greenish white fluorescence (Mondolot-Cosson et al 1997;Mondolot et al 2006). Hypothesizing that caffeine is in complex with chlorogenic acid within the vascular bundle and using a suggestion from the authors (Mondolot et al 2006 Since caffeine was visually determined to be on the periphery of cells, it might be possible that the molecule might be bound or in complex with cell wall phenolics.…”

The Synthesis and Storage Sites of Phenolic Compounds in the Root and Rhizome of <i>Echinacea purpurea</i>

“…Neu's solution is the standard test solution for localization of phenolic compounds in plants, in which borate will react with the phenolic compounds and form a complex, which will generate fluorescence of special color under certain conditions [17,18]. Astandard cichoric acid emits yellow green fluorescence (Figure 1(H)).…”