Phenol catechin

Total carotenoid Total Chlorophyll (a b) Total Chlorophyll-a Total Chlorophyll-b Poly phenols Catechins... 

Khokhar, S. and Magnusdottir, S.G.M., Total phenol, catechin, and caffeine contents of teas commonly consumed in the United Kingdom, J. Agric. Food Chem., 50, 565, 2002. 

The phenolics ( + )catechin and (— )epicatechin are common flavanols in several fruits (128). Apples and pears contain other phenolic compounds such as quinic, shikimic, chlorogenic, and caffeic acids (39). Durkee and Poapst (162) reported that the two major phenolic constituents of core tissues and seeds of McIntosh apples were chlorogenic acid and phloridzin. After hydrolysis of extracts from core tissues, the identified phenolics were phloretin, caffeic acid, p-coumaric acid, phloretic acid, and trace amounts of ferulic acid. Studies have shown that apple leucoanthocyanins yield catechin, epicatechin, cyanidin, and pelargonidin after hydrolysis (163, 164). Van Buren et al. (164) also reported that a purified leucoanthocyanin from apples was either a dimer or oligomer containing ( —) epicatechin, and 5,7,3, 4 -flavin-3,4-diol. 

Resveratrol has also been reported to offer protection against cardiovascular disease, such as coronary heart disease. The effects of resveratrol on factors implicated in the development of coronary heart disease - human platelet aggregation and the synthesis of eicosanoids (lipids) from arachidonate by platelets - were investigated and compared with the actions of other wine phenolics - catechin (1.39), epicatechin (7.18a), and quercetin (1.43) - and the antioxidants a-tocopherol (7.10a), hydroquinone and butylated hydroxytoluene. Resveratrol and quercetin demonstrated a dose-dependent inhibition of platelet aggregation, whereas the other compounds tested were inactive. Resveratrol also inhibited the synthesis of the eicosanoids in a dose-dependent manner, whereas the other phenolics were less effective of not effective at all. Removal of the alcohol from the wine did not diminish the effect on platelet aggregation (Pace-Asciak et al., 1995 Goldberg et al., 1995). 

Auger C, Teissedre PL, Gerain P, Lequeux N, Bomet A, Serisier S, Besancon P, Caporiccio B, Cristol JP, Rouanet JM. 2005. Dietary wine phenolics catechin, quercetin, and resveratrol efficiently protect hypercholesterolemic hamsters against aortic fatty streak accumulation. J Agric Food Chem 53 2015-2021. 

The phenolic catechins found in green tea are related to the phenol tyrosine, and it hence not surprising that they also can repair some of the radical-induced DNA damage in aqueous solution (Anderson et al. 2001). For being of any consequence for DNA repair in vivo (as sometimes suggested), they would have to accumulate near DNA, and this has not yet been shown to our knowledge. 

Chlorogenic acid (43-108 mg/kg fw. as caffeic acid) [19] and arbutin (1-gucosyl-1,4-dihydroxy-benzene) are the main non-flavonoid phenolics. Catechin and, especially, epicatechin (7-12 mg/kg) have also been found in pears [19]. In the peels, a complex flavonoid pattern of quercetin and isorhamnetin 3-glycosides has been detected. The occurrence of characteristic flavonols acylated with dicarboxylic acids in pears has recently been reported [28]. 

Therefore depending upon the conditions used to simulate either in vitro or in vivo oxidation, catechins or other phenolic compounds display differences in their antioxidant properties. Catechins also limited the consumption of a-tocopherol, allowing it to act as a scavenger within cell membranes whilst the catechins scavenged aqueous peroxyl radicals near the membrane surface (Pietta and Simonetti, 1998). 

Catechins are water-soluble however, they can be rendered insoluble by chemical reaction (Yayabe, 2001). Insoluble catechins do not lose their phenol hydroxyl groups, and their anti-bacterial and deodorising actions remain almost unaffected. In this form they are useful as natural anti-bacterial and deodorising materials for application to fibres and plastics. 

Various extraction methods for phenolic compounds in plant material have been published (Ayres and Loike, 1990 Arts and Hollman, 1998 Andreasen et ah, 2000 Fernandez et al., 2000). In this case phenolic compounds were an important part of the plant material and all the published methods were optimised to remove those analytes from the matrix. Our interest was to find the solvents to modily the taste, but not to extract the phenolic compounds of interest. In each test the technical treatment of the sample was similar. Extraction was carried out at room temperature (approximately 23 °C) for 30 minutes in a horizontal shaker with 200 rpm. Samples were weighed into extraction vials and solvent was added. The vials were closed with caps to minimise the evaporation of the extraction solvent. After 30 minutes the samples were filtered to separate the solvent from the solid. Filter papers were placed on aluminium foil and, after the solvent evaporahon, were removed. Extracted samples were dried at 100°C for 30 minutes to evaporate all the solvent traces. The solvents tested were chloroform, ethanol, diethylether, butanol, ethylacetate, heptane, n-hexane and cyclohexane and they were tested with different solvent/solid ratios. Methanol (MeOH) and acetonitrile (ACN) were not considered because of the high solubility of catechins and lignans to MeOH and ACN. The extracted phloem samples were tasted in the same way as the heated ones. Detailed results from each extraction experiment are presented in Table 14.2. 

EtOH extraction was the most efficient way to improve the flavour of the phloem. A solvent/solid ratio of at least 10 1/kg was needed to achieve a significant change in the taste. The loss of catechins was approximately 27% and that of lignans was 35%. All the catechins and lignans were found from the EtOH extract. Losses of lignans and catechins were smaller with other sovents, but either the taste was not modified or the cost of solvent treatment would be too high. Phenolic compounds like lignans and catechins also have a bitter taste and some improvement in flavour may have occurred because of the lower concentration of these. The disappearance of the characteristic... 

The chemical formulae for a variety of plant phenols are given in Fig. 16.2, including examples of simpler phenols, such as cinnamic acid derivative, and of tocopherols, flavonoids, flavonoid glycosides and anthocyanidins. The flavonoids include the following subclasses flavanones (taxifolin), flavones (luteolin), flavonols (quercetin) and flavanols (catechin/epicatechin). The... 

Morel et al. (1993) have reported that three flavanoids (catechin, quercetin and diosmetin) are cytoprotective on iron-loaded hepatocyte cultures. Their cytoprotective activity (catechin > quercetin > diosmetin) correlated with their iron-chelating ability (Morel et al., 1993). These compounds should also be good phenolic antioxidants so iron chelation may only be part of the story. 

The Folin-Ciocalteu assay is the most widely used method to determine the total content of food phenolics (Fleck and others 2008). Folin-Ciocalteu reagent is not specific and detects all phenolic groups found in extracts, including those found in extractable proteins. A disadvantage of this assay is the interference of reducing substances, such as ascorbic acid (Singleton and others 1999). The content of phenolics is expressed as gallic acid or catechin equivalents. 

Red wine contains quercetin, rutin, catechin, and epicatechin, among other flavonoids (Frankel and others 1993). Quercetin and other phenolic compounds isolated from wines were found to be more effective than a-tocopherol in inhibiting copper-catalyzed LDL oxidation. It has been determined that quercetin has also several anti-inflammatory effects it inhibits inflammatory cytokine production (Boots and others 2008), inducible NO synthase expression and activation of inflammatory transcription factors (Hamalainen and others 2007), and activity of cyclooxygenase and lipooxygenase (Issa 2006), among others. 

Jo and others (2006) applied this assay to determine the antioxidant properties of methanolic extracts from Japanese apricot in chicken breast meat. Likewise, Pearson and others (1998) assessed two types of Japanese green tea from Japan and two of their active compounds, catechin and epicatechin, for their relative abilities to inhibit the oxidation of LDL. Also, Pearson and others (1999) assessed the ability of compounds in apple juices and extracts from fresh apple to protect LDL. Heinonen and others (1998b) observed that berry phenolics inhibited hexanal formation in oxidized human LDL. 

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