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PubMed1999

Antioxidant polyphenols from tart cherries (Prunus cerasus).

Montmorency and Balaton tart cherries were lyophilized and sequentially extracted with hexane, ethyl acetate, and methanol. Methanolic extracts of dried Balaton and Montmorency tart cherries (Prunus cerasus) inhibited lipid peroxidation induced by Fe(2+) at 25 ppm concentrations. Further partitioning of this methanol extract with EtOAc yielded a fraction that inhibited lipid peroxidation by 76% at 25 ppm. Purification of this EtOAc fraction afforded eight polyphenolic compounds, 5,7,4'-trihydroxyflavanone (1), 5,7, 4'-trihydroxyisoflavone (2), chlorogenic acid (3), 5,7,3', 4'-tetrahydroxyflavonol-3-rhamnoside (4), 5,7,4'-trihydroxyflavonol 3-rutinoside (5), 5,7,4'-trihydroxy-3'methoxyflavonol-3-rutinoside (6), 5,7,4'-trihydroxyisoflavone-7-glucoside (7), and 6, 7-dimethoxy-5,8,4'-trihydroxyflavone (8), as characterized by (1)H and (13)C NMR experiments. The antioxidant assays revealed that 7-dimethoxy-5,8,4'-trihydroxyflavone (8) is the most active, followed by quercetin 3-rhamnoside, genistein, chlorogenic acid, naringenin, and genistin, at 10 microM concentrations.

Antioxidants↗
PubMed1970

Ontogeny and hormonal control of polyphenoloxidase isozymes in tobacco pith.

Isozymes of tobacco pith polyphenoloxidases (o-diphenol oxidase, EC 1.10.3.1) were separated electrophoretically from fresh pith of intact plants and from cultured pith sections. Extracts of fresh pith contained a poorly resolved complex of two to three anodic bands after starch gel electrophoresis at alkaline pH. This anodic complex was more active with chlorogenic acid than with 3,4-dihydroxyphenylalanine and was found in greater activity per gram fresh weight of tissue in younger internodes than in older ones. The longitudinal gradient of activity was thus the opposite of that found for the constitutive isozymes of peroxidase.A well defined cathodic band of polyphenoloxidase activity appeared after culture of pith in modified White's medium with shaking. This band, which was more active with 3,4-dihydroxyphenylalanine than with chlorogenic acid, could be detected after 1 to 2 days of incubation. Its appearance was enhanced by the addition of 10 mum indoleacetic acid; kinetin (1 mum tended to prevent this indoleacetic acid effect). Such hormonal control is opposite to that previously reported for the rapidly appearing new isozymes of peroxidase. The pattern of the major isozymes associated with polyphenoloxidase activities differs from that of peroxidase.

Catechol Oxidase↗
PubMed2000

Influence of PGRs on carbohydrate content in Lipaphis erysimi (Kalt.).

Six compounds (IBA, chlorogenic acid, cytokinine, GA3, alar B-9 and maleic hydrazide) belonging to four different categories of plant growth hormones were used to study their effect on carbohydrate content in L. erysimi. The second instar nymphs (48 hr old) were given both dipping and leaf surface treatment with 1024 ppm concentration of compounds for two time intervals i.e. 48 and 96 hr. The carbohydrate content decreased after treatment with 4 of the plant growth regulators i.e. GA3, alar B-9, IBA and chlorogenic acid with maximum suppression in GA3 treatment. Cytokinine did not induce any derogatory influence on carbohydrate content. The treatment with maleic hydrazide, on the other hand enhanced the carbohydrate content. It could be concluded that the application of these PGRs affected the carbohydrate synthesis or metabolism.

Animals↗
PubMed2000

Identification by HPLC-DAD and HPLC-MS analyses and quantification of constituents of fennel teas and decoctions.

Qualitative and quantitative differences among the constituents in various fennel (Foeniculum vulgare Mill., family Apiaceae) teas prepared by classical infusion, microwave decoction, and dissolution are reported. Different commercial starting materials, such as fruit (unbroken and crushed), four herbal teas, and two instant herbal teas were evaluated. Chlorogenic acid (1), quercetin-3-O-beta-D-glucuronide (2), p-anisaldehyde (3), and trans-anethole (4) were identified by HPLC-DAD and HPLC-MS as constituents of fennel teas. No coumarins, which are characteristic constituents of plants of Apiaceae family, were found. Trans-anethole (4), the main constituent of the essential oil, was present in all teas. In addition p-anisaldehyde (3), a degradation product of trans-anethole, was also identified in all teas with the exception of two samples. Chlorogenic acid (1) and quercetin-3-O-beta-D-glucuronide (2) were also present in all teas. In addition, minor unidentified flavonol constituents were found in two teas. Quality, activity, and safety of the content of the investigated preparations are also discussed.

Beverages↗
PubMed2004

Determination of active ingredients in Huangdan Yinchen Keli by CZE with amperometric detection.

A simple, reliable and reproducible method, based on capillary zone electrophoresis with amperometric detection (CZE-AD), has been developed for simultaneous determination of five active ingredients in complicated traditional Chinese medicines including chlorogenic acid, caffeic acid, aloe-emodin, emodin and rhein. A carbon-disk electrode was used as working electrode. The optimal conditions of CZE detection were 30 mM borate solution (pH 9.5) as running buffer, 18 kV as separation voltage and 1.00 V (versus Ag/AgCl) as detection potential. There was excellent linearity between current response and analyte concentration over two orders of magnitude, while the limits of detection were 1.1 x 10(-7), 3.0 x 10(-7), 1.5 x 10(-7), 2.9 x 10(-7), 1.4 x 10(-6) mol/l for aloe-emodin, emodin, rhein, chlorogenic acid and caffeic acid, respectively (S/N = 3). The utility of this method was demonstrated by monitoring a kind of complicated Chinese medicine named Huangdan Yinchen Keli. Two samples manufactured by different companies were monitored with satisfactory results.

Drugs, Chinese Herbal↗
PubMed2004

Effects of phenolics in Empire apples on hydrogen peroxide-induced inhibition of gap-junctional intercellular communication.

The present study investigated antioxidant and antitumor-promoting activities of major phenolic phytochemicals of apples. The contents of each antioxidant in Empire apples was quantified and their contributions to total antioxidant activity of apples were determined using assay for inhibition of 12-O-tetradecanoylphorbol-13-acetate-induced superoxide radical generation in cell culture model and expressed in vitamin C equivalent antioxidant capacity (VCEAC). The estimated contribution of major phenolics and vitamin C to total anitoxidant capacity of 100 g fresh Empire apples is as follows: quercetin (60.05 VCEAC) > chlorogenic acid (12.32) > phloretin (7.41) > procyanidin B2 (7.22) > vitamin C (6.61) > epicatechin (5.10) in superoxide radical scavenging assay. Recent reports suggest that the mechanism of carcinogenic process of hydrogen peroxide (H2O2) may be associated with the inhibition of gap-junctional intercellular communication (GJIC), which is involved in tumor promotion process. Apple extracts showed the protective effects against the inhibition of GJIC by H2O2 in a dose-dependent manner. Quercetin exerted the strongest protective effects among major antioxidants in apples on H2O2-induced inhibition of GJIC, following epicatechin, procyanidin B2, and vitamin C, while chlorogenic acid and phloretin had no effects. Our results indicate that cancer chemopreventive activity of apples is associated with the combined antioxidant capacity and antitumor-promoting activities of diverse antioxidants.

Antioxidants↗
PubMed1995

Creation of a Metabolic Sink for Tryptophan Alters the Phenylpropanoid Pathway and the Susceptibility of Potato to Phytophthora infestans.

The creation of artificial metabolic sinks in plants by genetic engineering of key branch points may have serious consequences for the metabolic pathways being modified. The introduction into potato of a gene encoding tryptophan decarboxylase (TDC) isolated from Catharanthus roseus drastically altered the balance of key substrate and product pools involved in the shikimate and phenylpropanoid pathways. Transgenic potato tubers expressing the TDC gene accumulated tryptamine, the immediate decarboxylation product of the TDC reaction. The redirection of tryptophan into tryptamine also resulted in a dramatic decrease in the levels of tryptophan, phenylalanine, and phenylalanine-derived phenolic compounds in transgenic tubers compared with nontransformed controls. In particular, wound-induced accumulation of chlorogenic acid, the major soluble phenolic ester in potato tubers, was found to be two- to threefold lower in transgenic tubers. Thus, the synthesis of polyphenolic compounds, such as lignin, was reduced due to the limited availability of phenolic monomers. Treatment of tuber discs with arachidonic acid, an elicitor of the defense response, led to a dramatic accumulation of soluble and cell wall-bound phenolics in tubers of untransformed potato plants but not in transgenic tubers. The transgenic tubers were also more susceptible to infection after inoculation with zoospores of Phytophthora infestans, which could be attributed to the modified cell wall of these plants. This study provides strong evidence that the synthesis and accumulation of phenolic compounds, including lignin, could be regulated by altering substrate availability through the introduction of a single gene outside the pathway involved in substrate supply. This study also indicates that phenolics, such as chlorogenic acid, play a critical role in defense responses of plants to fungal attack.

Journal Article↗
PubMed2006

Modulation of oxidative cell damage by reconstituted mixtures of phenolic apple juice extracts in human colon cell lines.

Diets rich in fruits and vegetables are associated with a lower risk of tumour induction in the intestine and other sites. Apple juice with high amounts of antioxidative phenolics might protect the intestine against reactive oxygen species-mediated cell damage. We investigated to which extent the preventive effectiveness of polyphenolic juice extracts is governed by the amounts of five major constituents (rutin, phloridzin, chlorogenic acid, caffeic acid and epicatechin). In human colon cell lines (Caco-2, HT29), reconstituted mixtures of these phenolics were investigated in comparison to the original juice extracts, originating from cider and table apples. Parameters studied were (oxidative) DNA damage (Comet assay), cellular redox status (dichlorofluorescein assay) and Trolox equivalent antioxidant capacity (TEAC). The TEAC of the reconstituted mixtures was higher compared to the respective original extracts (4.7-7.3 mM vs. 3.6-4.2 mM Trolox). After 24 h cell incubation, menadione-induced (oxidative) DNA damage was more effectively reduced by the reconstituted mixtures (1-100 microg/mL, 24 h), as compared to the original extracts. In contrast, the cellular ROS level was reduced to a rather similar extent by original extracts and reconstituted mixtures. The results lead to the conclusion that the selected constituents in their authentic proportions substantially account for the antioxidative effectiveness of phenolic apple juice extracts.

Antioxidants↗
PubMed2000

Reduction of phenoxyl radicals mediated by monodehydroascorbate reductase.

Monodehydroascorbate (MDA) reductase catalyzes the reduction of MDA, the only organic radical substrate for the enzyme reported so far. Here, we show that cucumber MDA reductase is also capable of reducing phenoxyl radicals which are generated by horseradish peroxidase (HRP) with H2O2. The addition of MDA reductase plus NADH suppressed the HRP/H2O2 dependent oxidation of quercetin, accompanied by the oxidation of NADH. The quenching of the quercetin radical by MDA reductase plus NADH was confirmed by ESR. MDA reductase with NADH also suppressed the HRP/H2O2 dependent oxidation of hydroxycinnamates, including ferulic acid, coniferyl alcohol, and chlorogenic acid. Thus, the phenoxyl radicals of plant phenols can be reduced to their respective parent phenols by MDA reductase via a mechanism similar to the reduction of MDA.

Escherichia coli↗
PubMed1982

The inhibitory effect of whole and deproteinized saliva on mutagenicity and clastogenicity resulting from a model nitrosation reaction.

The objective of this study was to simulate in vitro at least some of the conditions that prevail in man during ingestion of nitrate and nitrosable compounds. Human saliva has been chosen because most chemicals ingested through food will interact with saliva. The nitrosation of methylurea was used as a model because the nitrosation products can be readily detected by their mutagenic (his+ revertants of S. typhimurium) and clastogenic (chromosome aberrations in CHO cells) properties. The results show that human saliva inhibits the formation of mutagenic and clastogenic nitrosation products when present during nitrosation. A 50% inhibition of mutagenicity results from the addition of a saliva sample diluted at 5% of the original concentration. In the test system used a similar inhibitory effect was obtained by 2.5 mM ascorbic acid or 2.0 mM chlorogenic acid. The main inhibitory agents seem to reside in a deproteinized fraction which was filtered through an ultrafilter UM2 (greater than 1000 MW). At strong acid levels (below pH 2) the saliva loses its inhibitory effect on the nitrosation of methylurea. The contribution of saliva to the inhibition of endogenous nitrosation within the oral cavity or stomach is discussed.

Biotransformation↗
PubMed1992

Inhibition of platelet activation and endothelial cell injury by polyphenolic compounds isolated from Lonicera japonica Thunb.

Effects of the polyphenolic compounds isolated from Lonicera japonica Thunb on platelet aggregation, platelet thromboxane biosynthesis and hydrogen peroxide-induced endothelial cell injury were studied. With regard to the inhibitory effect on human platelet aggregation, methyl caffeate, 3,4-di-O-caffeoylquinic acid and methyl 3,4-di-O-caffeoylquinate had a strong effect. They significantly inhibited the second wave of platelet aggregation induced by ADP. Concerning thromboxane biosynthesis triggered by calcium ionophore A23187 in platelets, methyl caffeate and methyl 3,4-di-O-caffeoylquinate had the most potent inhibitory effect. Methyl 3,4-di-O-caffeoylquinate directly inhibited the conversion of arachidonic acid to thromboxane by platelet microsomes, while methyl caffeate did not have any significant effect on thromboxane biosynthesis in platelet microsomes. In the prevention of hydrogen peroxide-induced endothelial cell injury in culture, protocatechuic acid, methyl caffeate, methyl chlorogenic acid and luteolin were significantly effective. The inhibitory effect on platelet activation and the cytoprotective effect on hydrogen peroxide-induced cell injury may explain the possible role of polyphenolic compounds isolated from Lonicera japonica Thunb in maintaining vascular homeostasis.

Animals↗
PubMed2005

CO(2)-induced total phenolics in suspension cultures of Panax ginseng C. A. Mayer roots: role of antioxidants and enzymes.

The effects of different concentrations of CO(2) (1%, 2.5% and 5%) on the antioxidant capacity, total phenols, flavonoids, protein content and phenol biosynthetic enzymes in roots of Panax ginseng were studied in bioreactor (working volume 4 l) after 15, 30 and 45 days. CO(2) induced accumulation of total phenolics in a concentration and duration dependent manner. Total phenols, flavonoids and 1,1-diphenyl-2-picrylhydrazyl (DPPH) activity increased 60%, 30% and 20% at 2.5% CO(2) after 45 days compared to control in P. ginseng roots which indicated that phenolics compounds played an important role in protecting the plants from CO(2). Hypothesizing that increasing the phenolic compounds in roots of P. ginseng may increase its nutritional functionality; we investigated whether pentose phosphate pathway (PPP), shikimate/phenylpropanoid pathway enzymes have a role in phenolics mobilization in P. ginseng roots. Fresh weight (FW), dry weight (DW) and growth ratio was increased at 1% and 2.5% CO(2) only after 45 days, however, unaffected after 15 and 30 days. Results also indicated that high CO(2) progressively stimulated the activities of glucose 6 phosphate dehydrogenase (G6PDH, E.C. 1.1.1.49), shikimate dehydrogenase (SKDH, E.C. 1.1.1.25), phenylalanine ammonia lyase (PAL, E.C. 4.3.1.5), cinnamyl alcohol dehydrogenase (CAD, E.C. 1.1.1.195), caffeic acid (CA) peroxidase and chlorogenic acid (CGA) peroxidase after 15, 30 and 45 days. Increased CO(2) levels resulted in increases in accumulation of total protein (45%), non-protein thiol (NP-SH) (30%) and cysteine contents (52%) after 45 days compared to control and increased activities of beta-glucosidase (GS, E.C. 3.2.1.21) and polyphenol oxidase (PPO, E.C. 1.10.3.2) in P. ginseng roots indicated that they played an important role in protecting the plants from CO(2). These results strongly suggest that high concentration of CO(2) delivered to ginseng root suspension cultures induced the accumulation of total phenolics possessing high antioxidant properties probably useful for human health. Therefore, roots of P. ginseng are considered as a good source of phenolics compounds with high antioxidants capacity and can be produced on a large scale.

Alcohol Oxidoreductases↗
PubMed1998

Iridoids from Loasa acerifolia.

In the course of preliminary chemotaxonomic studies on Loasaceae from South and Central America, 30 species from 6 genera were screened by chromatographic means. From the aerial parts of Loasa acerifolia Dombey, the novel trimeric and dimeric iridoid glucosides acerifolioside and tricoloroside methyl ester, consisting of loganin and secoxyloganin moieties, were isolated. The structures were primarily elucidated by NMR spectroscopy. Loganin, loganic acid, rutin, scopoletin and chlorogenic acid were identified by cochromatography with reference compounds.

Central America↗
PubMed2001

Characterization of antioxidants present in hawthorn fruits.

Hawthorn fruit extract has been shown to have many health benefits including being cardiovascular protective, hypotensive and hypocholesterolemic. The present study was carried out to characterize further the antioxidants of hawthorn fruit and their effect on the oxidation of human low density lipoprotein (LDL) and alpha-tocopherol. The dry hawthorn fruit was extracted successively with ether, ethyl acetate, butanol and water. The ethyl acetate fraction was only effective in inhibition of Cu(+2)-mediated LDL oxidation. The column chromatographic separation led to isolation of eight pure compounds; namely, ursolic acid, hyperoside, isoquercitrin, epicatechin, chlorogenic acid, quercetin, rutin and protocatechuic acid. All of these phenolic compounds, except ursolic acid, were protective to human LDL from Cu(+2)-mediated LDL oxidation. They were also effective in preventing the peroxy free radical-induced oxidation of alpha-tocopherol in human LDL. The inhibitory effect of these compounds on oxidation of LDL and alpha-tocopherol was dose-dependent at concentrations ranging from 5 to 40 µM. In addition, supplementation of 2% hawthorn fruit powder significantly elevated serum alpha-tocopherol by 18-20% in rats fed a 30% polyunsaturated canola oil diet, as compared with the control. The present results suggest that part of the mechanism for cardiovascular protective effects of hawthorn fruit might also involve the direct protection to human LDL from oxidation or indirect protection via maintaining the concentration of alpha-tocopherol in human LDL.

Journal Article↗
PubMed2005

Seasonal variations in the level of plant constituents in greenhouse production of cherry tomatoes.

The content of selected plant constituents was measured in cherry tomatoes (Lycopersicon esculentumMill. cv. Jennita) during conventional Norwegian tomato production in a greenhouse from May until October 2004. Samples were collected according to standard production procedure with orange-yellow colored fruits at weight in the range of 12.4-19.3 g and size in the range of 28.9-33.0 mm (diameter). The content of selected compounds based on 100 g FW were found to vary in the following range during the season: 7.38-28.38 mg of chalconaringenin, 0.32-0.92 mg of rutin, 0.24-1.06 mg of chlorogenic acid, 5.60-20.02 mg of ascorbic acid, 1.60-5.54 mg of lycopene, and 0.37-0.55 mg beta-carotene. Only minute amounts of naringenin together with kaempferol 3-rutinoside and caffeic acid, which previously have been reported from tomatoes, were detected. The content of chalconaringenin to rutin and that of lycopene to beta-carotene showed a strong correlation during the season (p < 0.001). The content of total phenolics and methanol-soluble antioxidants also showed a correlation (p < 0.001), and were found in the range 14.6-32.6 mg of gallic acid equivalents (GAE)/100 g fresh weight (FW) and 445-737 micromol of Fe(II)/100 g FW, respectively. Seasonal variation in the level of plant constituents is shown to be related to photon flux density and fertilization level.

Antioxidants↗
PubMed2001

Plant catechols prevent lipid peroxidation in human plasma and erythrocytes.

The antioxidant activity of several plant catechol derivatives was tested in buffer, plasma, and human erythrocytes. In buffer, chlorogenic acid (CGA), caffeic acid (CA), and dihydrocaffeic acid (DCA) reduced ferric iron equally well in the ferric reducing antioxidant power (FRAP) assay. Low concentrations of the polyphenols enhanced the ability of plasma to reduce ferric iron by about 10%. In plasma, lipid hydroperoxide and F2-isoprostane formation induced by a water-soluble free radical initiator were reduced by CGA at concentrations as low as 20 microM. During incubation at 37 degrees C, human erythrocytes took up DCA, but not CGA, and intracellular DCA enhanced the ability of erythrocytes to reduce extracellular ferricyanide. When intact erythrocytes were exposed to oxidant stress generated by liposomes containing small amounts of lipid hydroperoxides, extracellular CGA at a concentration of 5 microM decreased both lipid peroxidation in the liposomes, and spared alpha-tocopherol in erythrocyte membranes. These results suggest that the catechol structure of these compounds convey the antioxidant effect in plasma and in erythrocytes.

Antioxidants↗
PubMed2004

Phenolic acid metabolites as biomarkers for tea- and coffee-derived polyphenol exposure in human subjects.

Tea and coffee are rich in polyphenols with a variety of biological activities. Many of the demonstrated activities are consistent with favourable effects on the risk of chronic diseases. 4-O-methylgallic acid (4OMGA) and isoferulic acid are potential biomarkers of exposure to polyphenols derived from tea and coffee respectively. 4OMGA is derived from gallic acid in tea, and isoferulic acid is derived from chlorogenic acid in coffee. Our major objective was to explore the relationships of tea and coffee intake with 24 h urinary excretion of 4OMGA and isoferulic acid in human subjects. The relationships of long-term usual (111 participants) and contemporaneously recorded current (344 participants) tea and coffee intake with 24 h urinary excretion of 4OMGA and isoferulic acid were assessed in two populations. 4OMGA was related to usual (r 0.50, P<0.001) and current (r 0.57, P<0.001) tea intake, and isoferulic acid was related to usual (r 0.26, P=0.008) and current (r 0.18, P<0.001) coffee intake. Overall, our present results are consistent with the proposal that 4OMGA is a good biomarker for black tea-derived polyphenol exposure, but isoferulic acid may be of limited usefulness as a biomarker for coffee-derived polyphenol exposure.

Biomarkers↗