Bound quinic acid as a measure of coupling of leaf and sunflower‐seed proteins with chlorogenic acid congeners: Loss of availability of lysine

Abstract

Changes were studied in the bulk protein of tobacco leaves, lucerne shoots and sunflower-seed kernels subjected to aerobic autolysis at room temperature. Bulk-protein fractions from cigar and from commercial sunflower-seed meal were also examined. Quinic acid, released by cold alkaline hydrolysis, was used as a measure of binding of chlorogenic acid residues to the proteins. On aerobic autolysis, the proteins of the leafy materials underwent some proteolysis; chlorogenic acid residues became bound to the protein, with concomitant diminution of free chlorogenic acid. The proteins showed browning, increased ultraviolet absorption and diminished content and "chemical availability" of lysine. However, during aerobic autolysis, the bulk protein of sunflower-seed kernels did not couple appreciably with the chlorogenic acid congeners present; the above accompanying phenomena were also largely absent. It is concluded that, when protein-rich plant materials are to be fed to monogastric animals, and particularly when their lysine content is critical, more attention should be paid to effects of the polyphenols and polyphenol oxidases present in the original plant, IntroductionThe nutritive quality of proteins (and particularly the availability of their lysine residues) may be adversely affected by reaction of the protein with quinonoid oxidation products arising from plant polyphenols (for reviews see refs. 1 4 ) . However, relevant detailed studies are still scanty. Recently Mbadiwe,s working with seeds of the legume Pentaclethra macrophylla Benth., which are rich in N-caffeoylputrescine,6*7 observed that, during prolonged storage of the seeds in air at room temperature, their protein became brown, showed diminished "chemically available" lysine and yielded putrescine on acid hydrolysis. Pierpoint and colleagues*-ll observed, in the presence of polyphenol oxidases, coupling of chlorogenic acid (3-0-caffeoylquinic acid) with thiol groups of cysteine residues and with eNH2 groups of certain lysine residues in some well-characterised proteins. They demonstrated charge-reversal, with expected changes of electrophoretic mobility. Since tobacco is rich in chlorogenic acid (and its i~o m e r s ) , l~-~~ and is also the only plant other than Peiitaclethra so far shown to contain N-caffeoylputre~cine,~~-~~ we hoped to observe oxidative coupling of both of these compounds to the leaf proteins, with different effects on their electrophoretic mobilities. To work with tobacco leaf should have the additional advantage that its proteins have been subjected to closer physicochemical characterisation than those of most other leaves. However, preliminary studies by Dr E. I. Mbadiwe have confirmed the observations of others,l7-19 that N-caffeoylputrescine is confined to young shoots and flowers in the normal tobacco plant. Accordingly, the work now described was limited to study of the coupling of the bulk protein of fairly mature leaves with chlorogenic acid.In view of current commercial interest in "green-crop fractionation"20 and in the p...

Nature of hydroxycinnamate-protein interactions

“…The development of sunflower seeds as a source for food proteins has been hampered to a large extent by the presence of phenolic compounds, especially chlorogenic acid. Earlier studies were directed in characterizing the role of covalent interactions under alkaline conditions in the process of optimizing the isolation of sunflower proteins (Cater et al 1972;Sabir et al 1974a;Davies et al 1978;Sosulski 1979a;Prasad 1988). A recent review clearly defines the difficulties encountered in preparing high-quality protein from sunflower and describes the processes needed to remove the phenolic compounds from the meals (Gonzalez-Perez and Vereijken 2007).…”

“…The analytical approaches to evaluate the hydroxycinnamates covalently bound to proteins include the following strategies: (1) Determination of bound quinic acid as a measure of coupling with chlorogenic acid (Davies et al 1978). Briefly, after saponification, the released quinic acid can be determined upon oxidation with periodic acid and subsequent treatment with thiobarbituric acid to give a pink color measured at 549 nm (Levy and Zucker 1960).…”

“…With respect to hydroxycinnamates, much work has been directed towards the significance of these interactions in complex food matrices in order to improve the nutritional and functional quality of plant proteins (Neucere et al 1978;Sosulski 1979b;Friedman 1996aFriedman , b, 1997Tsai and She 2006;Gonzalez-Perez and Vereijken 2007). A series of studies demonstrates that this primarily refers to the role of the interactions of chlorogenic acid (CQA) with the seed proteins as observed in, for example sunflower (Cater et al 1972;Sabir et al 1974a, b;Davies et al 1978;Sosulski 1979a;Prasad 1988;Saeed and Cheryan 1989;Rao 1990, 1991;Suryaprakash et al 2000;Gonzalez-Perez et al 2002;Gonzalez-Perez and Vereijken 2007), or in canola (Rubino et al 1996b;Naczk et al 1998;Diosady 2000, 2002). When reviewing the literature available, following locations or categories for the interactions of hydroxycinnamates and their derivatives can be identified: 1.…”

Vegetables and Vegetable Products

“…Even when extracted and fractionated anaerobically at -176 DC, lucerne LP contains phenolic material; part of it seems to be bound covalently to the protein (Laird et al 1976;Davies et al 1978). More phenolic material associates with LP when it is made or processed at room temperature without excluding air, and it accompanies the LP during such processes as coagulation, fractionation and washing.…”

Effect of rutin on the neonate sensitivity, dietary utilization and mid-gut carboxylesterase activity ofSpodoptera litura (Fabricius) (Lepidoptera: Noctuidae)

“…Several other modes-of-action have been suggested by Somogyi and Bonicke (1969), Davies et al (1978), Hoover et al (1977) and Wagner (1979). Perhaps the modes-of-action of rutin, both behavioural and physiological, change during the larval life of the insect, making it highly improbable to argue to a single mode-of-action.…”