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PubMed2006

Activity of grape extracts from Greek varieties of Vitis vinifera against mutagenicity induced by bleomycin and hydrogen peroxide in Salmonella typhimurium strain TA102.

Several in vivo and in vitro studies have shown that grape extracts could prevent certain steps in carcinogenesis and a few mechanisms have been proposed for this activity. In this study, the potential antimutagenic activity of methanolic and aqueous extracts from two Greek grape varieties of Vitis vinifera against DNA damage induced by reactive oxygen species (ROS) was assessed as a potential novel chemopreventive mechanism, using Salmonella typhimurium strain TA102. The two grape varieties were Assyrtiko (white grapes) and Mandilaria (red grapes), while the oxidant mutagens used were bleomycin (BLM) and hydrogen peroxide (H(2)O(2)). Since it has been considered that polyphenols present in grapes are their most potent biologically active compounds, we also tested the effects of polyphenol-rich fractions as well as some of the more common grape polyphenols on the activity of the two test mutagens. These polyphenols were quercetin, (+)-catechin, (-)-epicatechin, trans-resveratrol, gallic acid and protocatechuic acid. Almost all extracts showed inhibitory activity against both mutagens. On the other hand, polyphenol-rich fractions as well as individual polyphenols at concentrations found in the extracts either did not diminish or did enhance the activity of the mutagens. These results suggest that the protection of DNA from mutations induced by ROS may be one of the mechanisms accounting for the chemopreventive activity of grape extracts. However, it seems that this protective activity may not be attributed to polyphenols but rather to a synergism of many compounds in the grapes.

Antimutagenic Agents↗
PubMed2005

A blend of polyphenolic compounds explains the stimulatory effect of red wine on human endothelial NO synthase.

A high intake of polyphenolic compounds is likely to have beneficial effects on the cardiovascular system. Especially red wine is a rich source of polyphenols, and we have previously shown that French red wine upregulates eNOS, a protective enzyme in the cardiovascular system. The current study tested (poly)phenolic constituents of red wine for their ability to enhance eNOS expression (and the activity of a 3.5-kb human eNOS promoter) in human EA.hy 926 endothelial cells. Of the compounds tested, we found 3,4',5-trihydroxy-trans-stilbene (trans-resveratrol) to be the most efficacious stimulator of eNOS expression (and eNOS transcription), but this compound alone could not explain the total stimulatory effect of red wine. The flavanols catechin and epicatechin, the flavonols fisetin, myricetin, isoquercitrin and hyperoside, the anthocyanins delphinidin, malvidin, and paeonidin, gallic acid, and the hydroxycinnamic acids ferulic acid and sinapinic acid did not change eNOS expression or eNOS promoter activity in any substantial way. The flavonol quercetin inhibited eNOS expression (with no effect on eNOS promoter activity). Cinnamic acid was a rather potent enhancer of eNOS expression, however with an efficacy of only 170%. Surprisingly, it reduced eNOS promoter activity. The anthocyanins cyanidin, the hydroxycinnamic acids p-coumaric acid and caffeic acid, and the phenolic acids benzoic acid and vanillic acid also enhanced eNOS expression moderately (with no effect on eNOS promoter activity). Thus, the increase in eNOS in response to red wine involves several polyphenolic compounds with a major contribution from trans-resveratrol and lesser contributions from cinnamic and hydroxycinnamic acids, cyanidin, and some phenolic acids.

Anthocyanins↗
PubMed2006

Improvement of leukocyte functions in prematurely aging mice after five weeks of diet supplementation with polyphenol-rich cereals.

OBJECTIVE: We investigated the beneficial effects of diet supplementation with two types of cereals naturally rich in polyphenolic compounds on several functions of peritoneal leukocytes from prematurely aging mice (PAM). METHODS: Two-hundred sixty healthy mice, 8 wk of age, were recruited and their behavioral responses were tested in a simple T-maze to identify PAM. Then the mice were fed a diet supplemented with 20% (wt/wt) of two different cereal fractions, named B (wheat germ) and C (buckwheat flour), rich in polyphenols (gallic acid, catechin, p-hydroxybenzoic acid, vanillic acid, p-coumaric acid, sinapic acid, ferulic acid, quercetin, and rutin), or a standard diet (controls) for 5 wk. Several parameters of innate (adherence to tissues, chemotaxis, phagocytosis, microbicidal capacity, and natural killer activity) and acquired immune (lymphoproliferation and interleukin-2 release) responses were measured. RESULTS: The PAM control group showed worse immune functions (P < 0.001 to 0.05) compared with the non-PAM control group. The PAM group that received cereal B showed increases in phagocytosis (P < 0.01), microbicidal activity (P < 0.001 to 0.01), natural killer activity (P < 0.001) and lymphoproliferation in response to lipopolysaccharide (P < 0.01) and interleukin-2 release (P < 0.001), and the PAM group that received cereal C showed a similar pattern, with increases in macrophage chemotaxis (P < 0.01), phagocytosis (P < 0.01), microbicidal activity (P < 0.001 to 0.01), natural killer activity (P < 0.01), lymphoproliferative response to concanavalin A and lipopolysaccharide (P < 0.001), and interleukin-2 release (P < 0.001). CONCLUSIONS: Dietary supplementation with polyphenol-rich cereals appears to have a protective effect on immune cell functions in mice with premature senescence. Thus, regular intake of these compounds could delay normal aging and improve quality of life.

Aging↗
PubMed2004

Secretion, purification, and characterization of a recombinant Aspergillus oryzae tannase in Pichia pastoris.

Tannase (tannin acyl hydrolase) is an industrially important enzyme produced by a large number of fungi, which hydrolyzes the ester and depside bonds of gallotannins and gallic acid esters. In the present work, a tannase from Aspergillus oryzae has been cloned and expressed in Pichia pastoris. The catalytic activity of the recombinant enzyme was assayed. A secretory form of enzyme was made with the aid of Saccharomyces cerevisiae alpha-factor, and a simple procedure purification protocol yielded tannase in pure form. The productivity of secreted tannase achieved 7000 IU/L by fed-batch culture. Recombinant tannase had a molecular mass of 90 kDa, which consisted of two kinds of subunits linked by a disulfide bond(s). Our study is the first report on the heterologous expression of tannase suggesting that the P. pastoris system represents an attractive means of generating large quantities of tannase for both research and industrial purpose.

Aspergillus oryzae↗
PubMed2004

Studies on the aqueous extract of Terminalia chebula as a potent antioxidant and a probable radioprotector.

Aqueous extract of a natural herb, Terminalia chebula was tested for potential antioxidant activity by examining its ability to inhibit gamma-radiation-induced lipid peroxidation in rat liver microsomes and damage to superoxide dismutase enzyme in rat liver mitochondria. The antimutagenic activity of the extract has been examined by following the inhibition of gamma-radiation-induced strand breaks formation in plasmid pBR322 DNA. In order to understand the phytochemicals responsible for this, HPLC analysis of the extract was carried out, which showed the presence of compounds such as ascorbate, gallic acid and ellagic acid. This was also confirmed by cyclic voltammetry. The extract inhibits xanthine/xanthine oxidase activity and is also an excellent scavenger of DPPH radicals. The rate at which the extract and its constituents scavenge the DPPH radical was studied by using stopped-flow kinetic spectrometer. Based on all these results it is concluded that the aqueous extract of T. chebula acts as a potent antioxidant and since it is able to protect cellular organelles from the radiation-induced damage, it may be considered as a probable radioprotector.

Animals↗
PubMed2005

Nitric oxide synthase and cytokines gene expression analyses in Leishmania-infected RAW 264.7 cells treated with an extract of Pelargonium sidoides (Eps 7630).

A modern aqueous-ethanolic formulation of the roots of Pelargonium sidoides (Eps 7630), elaborated from the traditional herbal medicine used in areas of southern Africa, is effectively employed for the treatment of ENT and respiratory tract infections in modern phytotherapy. Previous studies have demonstrated antibacterial and immunomodulatory activities. To gain insight into the mode of action at the molecular level, gene expression analyses for the inducible nitric oxide synthase and the cytokines interleukin (IL)-1, IL-12, IL-18, tumour necrosis factor (TNF)-alpha, interferon (IFN)-alpha, and IFN-gamma, were performed using reverse transcription-polymerase chain reaction (RT-PCR). The experiments were carried out in parallel in non-infected and in Leishmania major-infected RAW 264.7 cells and the expression profiles were compared with those mediated by IFN-gamma+LPS. Eps 7630 induced low mRNA levels in non-infected cells, and it considerably up-regulated the transcript expressions in parasitised cells. Interestingly, and in contrast to activation by IFN-gamma+LPS, Eps 7630 also stimulated infected cells to produce IFN-gamma mRNA. A similar expression profile was observed for the methanol-insoluble fraction (MIF) of Eps 7630 and gallic acid, a trace constituent of the extract, while the methanol-soluble fraction and umckalin, an exclusive and representative member of the occurring coumarins, proved to be devoid of any remarkable gene-inducing capabilities. The present results provide not only convincing support for the improvement of immune functions as previously demonstrated in functional bioassays, but also evidence for activation at the transcriptional level and suggest that the underlying inducing principle is located in the MIF.

Animals↗
PubMed2004

Response of DNA, proteins and membrane bilayer in the digestive gland cells of freshwater mussel Unio tumidus to tannins exposure.

Exposure of digestive gland cells (Unio tumidus) in in vitro study to tannins (tannic, ellagic and gallic acid) caused changes in three types of cellular macromolecules, i.e. lipids, proteins and DNA. Two fluorescence probes: TMA-DPH and 12-AS were used to assess the membrane fluidity after incubating cells with different concentrations of tannins (1-60 microM). It was noticed that tannins increased the fluidity in the internal region of the lipid bilayer, but no changes at the surface of the plasma membrane were observed. The number of protein-bound carbonyl groups was quantitated spectrophotometrically using 2,4-dinitrophenylhydrazine (DNPH) assay. Oxidative modification of proteins increased in the cells exposed to tannins in a concentration-dependent manner. Results also showed an increase in carbonyl groups formation after exposing the cells to complex: tannin-Cu(2+) ions. We also investigated the effect of tannins on the level of nuclear DNA damage using the comet assay. We showed that these compounds at 15, 30 and 60 microM induced DNA damage. At these concentrations cell viability measured by trypan blue exclusion assay was not reduced by more than 30%. We also added Cu(2+) ions at 50 microM to assess the influence of the complex tannin-Cu(2+) on DNA lesions. The same method was used to study the possibility to repair this damage in DNA. Experimental data showed that tested polyphenolic acids do not contribute to the induction of strand breaks in nucleic acid at the smallest dose--1 microM and in this range they have a protective effect against the activity of 50 microM Cu(2+) ions.

Animals↗
PubMed2005

Measurement of DNA damage and protein oxidation after the incubation of B14 Chinese hamster cells with chosen polyphenols.

The spectrophotometric method with 2,4-dinitrophenylhydrazine (DNPH) and the alkaline single-cell gel electrophoresis (comet assay) were used to assess the possibility of three polyphenolic compounds (tannic, ellagic and gallic acid) to induce the changes in proteins and DNA. B14 Chinese hamster cells were exposed to various concentrations of used polyphenols (1-60 microM), hydrogen peroxide (10 and 40 microM) copper ions (50 microM), and the effect of phenols alone and in combination with Cu2+ ions and H2O2 was determined. The results reveal that polyphenolic acids in higher concentrations than 1 microM contribute to the changes in the tested molecules and cause protein and DNA damage. The combined treatment of polyphenols with Cu2+ ions and with H2O2 demonstrates that the lowest dose of phenols (1 microM) can act as an antioxidant agent against used chemicals. The DNA repair process was also studied. The data obtained in this experiment demonstrate that the most effective DNA repair occurs 1h after the removal of phenolic compounds. The used methods and obtained results provide additional information about the potential use of these phenols not only as antioxidants but also as pro-oxidants in biological systems.

Animals↗
PubMed2006

Composition of a protein-like fluorophore of dissolved organic matter in coastal wetland and estuarine ecosystems.

This study demonstrates the compositional heterogeneity of a protein-like fluorescence emission signal (T-peak; excitation/emission maximum at 280/325 nm) of dissolved organic matter (DOM) samples collected from subtropical river and estuarine environments. Natural water samples were collected from the Florida Coastal Everglades ecosystem. The samples were ultrafiltered and excitation-emission fluorescence matrices were obtained. The T-peak intensity correlated positively with N concentration of the ultrafiltered DOM solution (UDON), although, the low correlation coefficient (r(2)=0.140, p<0.05) suggested the coexistence of proteins with other classes of compounds in the T-peak. As such, the T-peak was unbundled on size exclusion chromatography. The elution curves showed that the T-peak was composed of two compounds with distinct molecular weights (MW) with nominal MWs of about >5 x 10(4) (T(1)) and approximately 7.6 x 10(3) (T(2)) and with varying relative abundance among samples. The T(1)-peak intensity correlated strongly with [UDON] (r(2)=0.516, p<0.001), while T(2)-peak did not, which suggested that the T-peak is composed of a mixture of compounds with different chemical structures and ecological roles, namely proteinaceous materials and presumably phenolic moieties in humic-like substances. Natural source of the latter may include polyphenols leached from senescent plant materials, which are important precursors of humic substances. This idea is supported by the fact that polyphenols, such as gallic acid, an important constituent of hydrolysable tannins, and condensed tannins extracted from red mangrove (Rhizophora mangle) leaves exhibited the fluorescence peak in the close vicinity of the T-peak (260/346 and 275/313 nm, respectively). Based on this study the application of the T-peak as a proxy for [DON] in natural waters may have limitations in coastal zones with significant terrestrial DOM input.

Chromatography, Gel↗
PubMed2003

Chain-breaking antioxidant activity of natural polyphenols as determined during the chain oxidation of methyl linoleate in Triton X-100 micelles.

Natural polyphenols (PP) are known as potent antioxidants, which are believed to prevent many degenerative diseases, including cancer and atherosclerosis. Much attention in the literature has been given to the antioxidant activity of PP-containing products; however, information on the antioxidative properties of individual PP is rather poor and controversial. In this work, the chain-breaking antioxidant activities of several natural PP and their synthetic analogs were determined during the chain oxidation of methyl linoleate in an aqueous buffered, pH 7.40, micellar solution of Triton X-100, induced by 2,2'-azobis(2-amidinopropan) dihydrochloride at 37 degrees C. Use of the mode of the controlled chain reaction allowed separate determination of the rate constant for the reaction of PP with the lipid peroxy radical and the stoichiometric factor of inhibition (f), which shows how many kinetic chains can be terminated by one molecule of PP. All the PP studied display a pronounced antioxidant activity. A significant difference in f value between catechol derivatives and pyrogallol derivatives was found. While with pyrogallol derivatives (gallic acid, epigallocatechin, propyl gallate, myricetin), f was found to be around 2, the theoretically expected value, f, for catechol derivatives (catechol, catechin, epicatechin, quercetin, rutin, caffeic acid) was found to be within the range 3.6-6.3. The elevated antioxidant capacity of catechol derivatives may be explained by the contribution of products of PP oxidative transformation, most likely by dimers, to inhibition. With catechin, epicatechin, and quercetin, the reactivity of products exceeds that of original PP. A real chain-breaking antioxidant activity of PP is likely determined not so much by the reactivity of the original PP as by the probability of the formation of active products and their antioxidant activities. The above findings were applied to explain some features of the antioxidant activity of teas and red wines.

Antioxidants↗
PubMed1997

Exogenous phosphatidic acid with saturated short-chain fatty acyl groups induces superoxide anion release from guinea pig peritoneal polymorphonuclear leukocytes by three different mechanisms.

Treatment of suspensions of guinea pig peritoneal polymorphonuclear leukocytes (PMN) with four species of phosphatidate (PA) containing short-chain fatty acids induced sustained superoxide anion (O2-) production after a lag time. The rank order of efficiency of these PAs in triggering O2- production was PA8:0 [1,2-dioctanoyl-sn-glycerol-3-phosphate (GP)] > PA10:0 (1,2-didecanoyl-GP) > PA6:0 (1,2-dicaproyl-GP) > > PA12:0 (1,2-dilauroyl-GP). The O2- release from PMN stimulated with PA10:0 or PA12:0, but not with PA6:0 or PA8:0, was lowered by the addition of 1 mM extracellular Ca2+. Studies with various inhibitors showed that the mechanism of multiphasic O2- production induced by PA8:0 depended on its concentration: 1 and 3 microM PA8:0 induced O2- production constantly after a lag time through a protein kinase-dependent mechanism that was inhibited by 100 nM staurosporine. With concentrations of PA of 10 microM or more, an additional mechanism that was independent of protein kinase became operative and predominant over the protein kinase-dependent one. This protein kinase-independent mechanism was inhibited selectively by 80 microM TMB-8. Concentrations of 30, 60 and 100 microM PA first elicited transient O2- production via another protein kinase-dependent mechanism that was more sensitive to H-7 than to staurosporine, and then sustained O2- production, mainly driven by the protein kinase-independent mechanism. Metabolism of exogenously added [14C]PA8:0 in intact PMN was examined in the presence and absence of propranolol. Results suggest that PA itself is more important rather than its degradation products such as diacylglycerol, in inducing O2- production via three different mechanisms described above.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1992

Suppressive effect of carbachol on forskolin-stimulated neurite outgrowth in human neuroblastoma NB-OK1 cells.

We have used human neuroblastoma NB-OK1 cells to investigate the regulation of neurite outgrowth. Carbachol suppressed forskolin-stimulated neurite outgrowth in NB-OK1 cells although forskolin-stimulated cAMP levels were enhanced. The dose-response curve for this suppression was very similar to that for stimulation of inositol monophosphate (IP1) formation and for stimulation of the initial rise of [Ca2+]i elicited by carbachol. Carbachol-mediated changes in neurite outgrowth, IP1 formation and [Ca2+]i displayed high sensitivity for pirenzepine but low sensitivity for AF-DX116. Inhibition of intracellular calcium release with TMB-8 prevented the suppressive effect of carbachol on forskolin-stimulated neurite outgrowth. Hence we describe for the first time a relationship between neurite outgrowth and inositol triphosphate-triggered calcium release mediated by carbachol in the human neuron-derived cell line.

Atropine↗
PubMed1986

No synergism between ionomycin and phorbol ester in fatty acid synthesis by isolated rat hepatocytes.

With hepatocytes in suspension, freshly isolated from meal-fed rats, no significant effect of ionomycin on the rate of de novo fatty acid synthesis was observed, whereas phorbol myristate acetate (PMA) was strongly stimulatory. The combination of ionomycin and PMA produced the same stimulation as was seen with PMA alone. Stimulation of fatty acid synthesis by vasopressin was comparable and not additive to that observed with PMA, indicating that activation of protein kinase C is solely responsible for this metabolic effect of vasopressin. Both vasopressin and PMA increased acetyl-CoA carboxylase activity in isolated rat hepatocytes.

Acetyl-CoA Carboxylase↗
PubMed2002

Antioxidant effects of green tea polyphenols on free radical initiated peroxidation of rat liver microsomes.

Antioxidative effects of the principal polyphenolic components extracted from green tea leaves, i.e. (-)-epicatechin (EC), (-)-epicatechin gallate (ECG), (-)-epigallocatechin gallate (EGCG), (-)-epigallocatechin (EGC), and gallic acid (GA), against free radical initiated peroxidation of rat liver microsomes were studied. The peroxidation was initiated by a water-soluble azo compound 2,2'-azobis(2-amidinopropane hydrochloride (AAPH). The reaction kinetics was monitored by oxygen uptake and formation of malondialdehyde (MDA). Kinetic analysis of the antioxidation process demonstrates that these green tea polyphenols (GOHs), especially EC and ECG which bear ortho-dihydroxyl functionality, are good antioxidants for microsomal peroxidation. The antioxidant synergism of these GOHs with the endogenous alpha-tocopherol (TOH) (vitamin E) is also discussed.

Animals↗
PubMed2000

Synthesis, structure, and thermal properties of 1,2-dipalmitoylgalloylglycerol (DPGG), a novel self-adhering lipid.

A novel diacyl glycerol-based lipid with a polyphenolic head group has been synthesized and characterized. X-ray diffraction experiments show that this lipid, 1,2-dipalmitoylgalloylglycerol (DPGG), hydrates to form gel phase bilayers at 20 degrees C with extremely narrow interbilayer fluid separations, indicating that apposing DPGG bilayers strongly adhere to each other. Differential scanning calorimetry shows that fully hydrated DPGG exhibits a pretransition exotherm (3.7 kcal/mol) at 52 degrees C and a high enthalpy (11.3 kcal/mol) main endothermic transition at 69 degrees C. These thermal properties are similar to those of galactosylceramides with similar hydrocarbon chain compositions. The adhesive and thermal properties of DPGG are likely due to both intermolecular hydrogen-bonding and hydrophobic interactions between the aromatic rings on the gallic acids.

Calorimetry, Differential Scanning↗
PubMed1989

Nuclear envelope breakdown and mitosis in sand dollar embryos is inhibited by microinjection of calcium buffers in a calcium-reversible fashion, and by antagonists of intracellular Ca2+ channels.

Transient elevations in intracellular free Ca2+ are believed to signal the initiation of mitosis. This model predicts that mitosis might be arrested prior to nuclear envelope breakdown (NEB) or anaphase onset if intracellular Ca2+ concentration is buffered or dampened. Microinjection of a discrete dose of Ca2+ into the cell might then release the cell to resume mitotic cycling. Experimentally, one blastomere of two cell sand dollar (Echinaracnius parma) embryos was microinjected with Ca2+ buffers, Ca2+ solutions, or Ca2+ channel antagonists; the uninjected blastomere was the control. Cells were loaded with 10 pl doses of the Ca2+ buffer antipyrylazo III (ApIII) at specific times in the cell cycle to attempt a competitive inhibition of Ca2+-dependent steps in NEB and initiation of mitosis. Injection of 50 microM ApIII 6 min prior to NEB blocked NEB and further cell cycling. Injections of solutions between 0 and 30 microM ApIII were without observable effect. Control injections had no observable effect on the injected cell. Cells injected with 50 microM ApIII 2 min prior to the onset of anaphase in control cells were blocked in metaphase. Cells were sensitive to Ca2+ buffer injections 6 min prior to NEB (with a 40- to 45-sec duration), and 2 min prior to anaphase onset (with a 10- to 20-sec duration). Vital staining of these cells with H33342 demonstrated that they contained only one nucleus that had the same fluorescence intensity as seen prior to microinjection, and thus did not undergo DNA synthesis following the imposition of the Ca2+ buffer block to mitosis. Cells arrested in this fashion did not spontaneously resume mitotic cycling. This Ca2+ buffer-induced mitotic arrest was, however, experimentally reversible. Cells arrested with 50 microM ApIII 6 min prior to NEB could be returned to mitotic activity by injecting 300 microM CaCl2 5 min after the ApIII injection. The double injected cells resumed cycling, NEB, and mitosis after a delay of one cell cycle period, and remained one cell cycle out of phase with the sister (control) cell. Microinjection of antagonists of endomembrane Ca2+ channels inhibited NEB and anaphase onset in a concentration- and time-dependent fashion. The effective doses of compounds tested were 7 micrograms/ml ryanodine and 500 micrograms/ml TMB-8. These results indicate that a transient elevation of intracellular Ca2+ from endomembrane stores is required to initiate mitotic events, namely NEB and anaphase onset.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1998

Synthesis, antimicrobial activity and bleaching effect of some reaction products of 4-oxo-4H-benzopyran-3-carboxaldehydes with aminobenzothiazoles and hydrazides.

The synthesis of the biologically active novel systems derived from reaction of 3-formylchromones with three types of amino derivatives, 6-R2-2-aminobenzothiazoles, 6-amino-2-R3-thiobenzothiazoles and hydrazide derivatives (derived from cyanoacetic, isonicotine, salicylic and gallic acids) was carried out. The structures of the prepared compounds have been proved by elemental analysis, 1H NMR and IR spectra. Antimicrobial activity was studied against the following microorganisms--bacteria G+ (Staphylococcus aureus 29/58, Bacillus subtilis 18/66), G- (Escherichia coli 326/71, Pseudomonas aeruginosa); yeasts: Candida albicans, Saccharomyces cerevisiae; moulds: Microsporum gypseum, Aspergillus niger, Scopulariopsis brevicaulis; and against typical and atypical mycobacteria: Mycobacterium tuberculosis (H37Rv), Mycobacterium kansasii (PFG 8), Mycobacterium avium (My 80/72), Mycobacterium fortuitum (1021). The hereditary bleaching effect on the plastid system of Euglena gracilis, a unique phenomenon of the biological activity of chromone derivatives, is reported. The bleaching test on E. gracilis is used for detecting extranuclear mutations.

Anti-Bacterial Agents↗
PubMed2000

Comparative analysis of tea catechins and theaflavins by high-performance liquid chromatography and capillary electrophoresis.

This paper describes the simultaneous determination of catechins and theaflavins in green and black teas, using reversed-phase high-performance liquid chromatography (HPLC) and capillary electrophoresis (CE). The tea polyphenols analyzed included (+)-catechin, catechin gallate, (-)-epicatechin, epicatechin-3-gallate, epigallocatechin, epigallocatechin-3-gallate, theaflavin, theaflavin-3-monogallate, theaflavin-3'-monogallate and theaflavin-3,3'-gallate. These polyphenols together with six other tea ingredients such as caffeine, adenine, theophylline, quercetin, gallic acid and caffeic acid were separated within 27 min by HPLC and in less than 10 min by CE. The optimal analytical conditions of both chromatographic methods were investigated for the convenience and reliability for routine analysis. Both HPLC and CE were found to be reliable and compatible. The reproducibility of the within-day assay using both methods was generally >90%. The day-to-day variation of retention time was <5% for HPLC, while the variation of migration time for CE was <2%. The analysis time of CE was three-times faster, however it is five-times less sensitive than HPLC, which has detection limits of 0.05 microg/ml and 0.5 microg/ml for catechins and theaflavins, respectively.

Biflavonoids↗