Localization and Identification of Phenolic Compounds in Theobroma cacao L. Somatic Embryogenesis

Abstract

Cocoa breeders and growers continue to face the problem of high heterogeneity between individuals derived from one progeny. Vegetative propagation by somatic embryogenesis could be a way to increase genetic gains in the field. Somatic embryogenesis in cocoa is difficult and this species is considered as recalcitrant. This study was conducted to investigate the phenolic composition of cocoa flowers (the explants used to achieve somatic embryogenesis) and how it changes during the process, by means of histochemistry and conventional chemical techniques. In flowers, all parts contained polyphenolics but their locations were specific to the organ considered. After placing floral explants in vitro, the polyphenolic content was qualitatively modified and maintained in the calli throughout the culture process. Among the new polyphenolics, the three most abundant were isolated and characterized by 1H- and 13C-NMR. They were hydroxycinnamic acid amides: N-trans-caffeoyl-l-DOPA or clovamide, N-trans-p-coumaroyl-l-tyrosine or deoxiclovamide, and N-trans-caffeoyl-l-tyrosine. The same compounds were found also in fresh, unfermented cocoa beans. The synthesis kinetics for these compounds in calli, under different somatic embryogenesis conditions, revealed a higher concentration under non-embryogenic conditions. Given the antioxidant nature of these compounds, they could reflect the stress status of the tissues.

Ecophysiology of the cacao tree

“…These flowers contain different polyphenolic compounds such as: (i) hydroxycinnamic acids, located in the periphery of the organs, except in the ovary where parenchyma cells are present and ovules occur, and (ii) tannins and anthocyanins, both located in the epidermis of different floral parts. Anthocyanins are mainly restricted to ornamentation in petals and staminoids (Alemanno et al, 2003). These external locations of phenolic compounds can work as a chemical protective barrier against damages promoted by environmental factors (Alemanno et al, 2003).…”

“…Anthocyanins are mainly restricted to ornamentation in petals and staminoids (Alemanno et al, 2003). These external locations of phenolic compounds can work as a chemical protective barrier against damages promoted by environmental factors (Alemanno et al, 2003).…”

Polyphenols Distribution and Reserve Substances Analysis in Cocoa Somatic Embryogenesis

“…2K, 4A). Moreover, consistent with Alemanno et al (2003), somatic embryos that regenerated were free of inner polyphenols, and only small amounts were distributed in the periphery of the embryo epidermal layer, while in the non-regenerating variety, embryogenic calli were compact and such structures contained polyphenols randomly distributed across all tissues. Polyphenols were abundant in staminodes and petals on day 0, but their distribution changed during the development process according to genotype and embryogenic capacity.…”

“…High concentrations are associated with the non-regenerating response of somatic embryos (Alemanno, 2003) and histolocalization of phenolic compounds could be a marker to distinguish regenerating and non-regenerating embryos. Further early screening of phenol content in the tissue culture will help in predicting developmental events in cacao.…”

Synthesis of Clovamide Analogues That Inhibit NO Production in Activated BV-2 Microglial Cells

“…Only a few studies conducted with the synthesized analogues or derivatives, such as lipophilic clovamide-type derivatives such as N-caffeoyl tyrosine methyl ester, N-ferulyl L-dopa alkyl ester and N-sinapinyl L-dopa alkyl ester (alkyl=methyl, dodecyl), have revealed potent antioxidant activities in bulk lipids and moderated protectants in emulsions. 8,19) As part of our program to find a potent inhibitor of NO production, we recently found that clovamide derivative, 3-(3,4-dihydroxy-phenyl)-2-[4-(3-trifluoromethylphenyl)-but-2-enoylamino]-propionic acid methyl ester, revealed antiinflammatory effect in lipopolysaccharide (LPS) stimulated rat derived primary cells, as well as murine BV-2 microglial cells. 20) With the aim of improving the potency and elucidating the pharmacophore of clovamide, we modified clovamide by replacing the catechol group in caffeic acid and L-dopa with various functional groups.…”