N-Terminal Amino Acid Sequence of the Chlorophyll-binding Protein CP-47 of Photosystem 2 in the Thermophilic Cyanobacterium Synechococcus elongatus

Effects of caffeic acid and chlorogenic acid on mutagenicity were studied using the Salmonella typhimurium system. These compounds had inhibitory effects on the mutagenicity of Trp-P-1 and Glu-P-2. Caffeic acid completely eliminated the mutagenicity induced by activated Glu-P-2. Some compounds analogous to caffeic acid, such as cinnamic acid, coumaric acid, and ferulic acid, also significantly decreased the mutagenicity of Glu-P-2.     

Evaluation of a genotoxicity test measuring DNA-strand breaks in mouse lymphoma cells by alkaline unwinding and hydroxyapatite elution

A rapid genotoxicity test, based on the measurement of the proportion of single- to double-stranded DNA by alkaline unwinding and hydroxyapatite elution in mouse lymphoma cells treated in vitro with various chemicals, was evaluated. Seventy-eight compounds from diverse chemical groups, including commonly tested mutagens, toxic compounds not usually tested for genotoxicity and non-toxic compounds not thought to be genotoxic were tested. The results obtained were compared with those from the mouse lymphoma TK locus forward-mutation assay, providing a basis for assessing the relative sensitivity of the 2 assays using the same cells exposed to chemicals under similar conditions. Clear evidence of DNA-damaging activity was obtained with 43 of the compounds, while 4 gave equivocal results. Of the remaining 31 compounds, 14 were toxic without inducing DNA damage while the rest were non-toxic and did not induce any DNA damage. Results were available from both the alkaline unwinding assay and the mouse lymphoma assay for 61 compounds; they showed a concordance between the 2 assays of 77%. Of the 47 compounds that were positive or equivocal in the alkaline unwinding assay, only carbon tetrachloride and prednisolone were negative in the mouse lymphoma assay, while 12 of the 19 compounds that were negative in the alkaline unwinding assay were positive in the mouse lymphoma assay. These included 3 compounds that interfere with nucleic acid metabolism, and 3 crosslinking agents, which would be expected to produce mutations to a greater extent than strand breaks. The other 6 compounds were anthranilic acid, benzoquinone, p-chloroaniline, diethylmaleate, glucose and procarbazine HCl. Of these only the last is a known carcinogen. It is concluded from the present study that there was good overall agreement between the results of the DNA alkaline unwinding and mouse lymphoma TK locus assays, but that the sensitivity of the alkaline unwinding assay is lower for some classes of compounds. Bearing this in mind, the alkaline unwinding assay is considered suitable as a rapid screen for genotoxic activity in eukaryotic cells.     

Inhibition by chlorogenic acid of haematin-catalysed retinoic acid 5,6-epoxidation.

Chlorogenic acid (3-O-caffeoylquinic acid) inhibited haematin- and haemoglobin-catalysed retinoic acid 5,6-epoxidation. Some other phenol compounds (caffeic acid and 4-hydroxy-3-methoxybenzoic acid) also showed inhibitory effects on the haematin- and haemoglobin-catalysed epoxidation, but salicylic acid did not. Of the above compounds, caffeic acid and chlorogenic acid were potent inhibitors compared with the other two, suggesting that the o-hydroquinone moiety of chlorogenic acid and caffeic acid is essential to the inhibition of the epoxidation. Although caffeic acid inhibited retinoic acid 5,6-epoxidation requiring the consumption of O2, formation of retinoic acid radicals was not inhibited on the addition of caffeic acid to the incubation mixture. The above results suggest that caffeic acid does not inhibit the formation of retinoic acid radicals but does inhibit the step of conversion of retinoic acid radical into the 5,6-epoxide.     

3-Desoxyanthocyanin and other phenolics in the water fernAzolla

The phenolic compounds ofAzolla imbricata andA. japonica have been examined in the present study. Both species were found to contain luteolinidin 5-glucoside and several phenolic compounds, particularly chlorogenic acid, aesculetin, caffeic acid 3,4-diglucoside and 6-(3′-glucosylcaffeoyl)-aesculetin. In addition, glucose esters ofp-coumaric acid and glucose, 1,6-diester of caffeic and chlorogenic acids were present in a small amount. The acid- and alkali-hydrolyzates ofAzolla plants yielded caffeic acid and aesculetin present at the level of about 0.047% and 0.012% in fresh plants, and a large part of the caffeic acid seems to be present as the ester.     

Genotoxicity of 6 oxime compounds in the salmonella/mammalian-microsome assay and mouse lymphoma TK +/- assay

To aid in the selection of chemical candidates for in vivo tests, the mutagenicity of 6 oxime compounds was evaluated in the Salmonella plate incorporation assay and mouse lymphoma L5178Y TK +/- assay. All of the oximes were mutagenic in the mouse lymphoma assay in the absence of exogenous metabolic activation. Acetaldehyde oxime was also mutagenic in the presence of S9 activation. In contrast to these results, a positive response was noted only for 2-(hydroxyimino)-N-phenyl-acetamide oxime in strain TA1535 in the absence of activation in the Salmonella/microsome test.     

Genotoxicity of 6 oxime compounds in the Salmonella/mammalian-microsome assay and mouse lymphoma TK+/− assay

To aid in the selection of chemical candidates for in vivo tests, the mutagenicity of 6 oxime compounds was evaluated in the Salmonella plate incorporation assay and mouse lymphoma L5178Y TK^+/− assay. All of the oximes were mutagenic in the mouse lymphoma assay in the absence of exogenous metabolic activation. Acetaldehyde oxime was also mutagenic in the presence of S9 activation. In contrast to these results, a positive response was noted only for 2-(hydroxyimino)-N-phenyl-acetamide oxime in strain TA1535 in the absence of activation in the Salmonella/microsome test.     

Stability and bioavailability of antioxidants in garland (Chrysanthemum coronarium L.)

The stability and bioavailability of the major antioxidants in garland (Chrysanthemum coronarium L.), chlorogenic acid, 3,5-dicaffeoylquinic acid and 4-succinyl-3,5-dicaffeoylquinic acid, were investigated together with caffeic acid. These compounds were stable in artificial digestive juice, but more than 90% of them disappeared from plasma within 30 min after intravenous injection into rats. When they were orally administered, only caffeic acid could be detected.     

Free radical scavengers from Cymbopogon citratus (DC.) stapf plants cultivated in bioreactors by the temporary immersion (TIS) principle

The biomass production of Cymbopogon citratus shoots cultivated in bioreactors according to the temporary immersion (TIS) principle was assessed under different growth conditions. The effect of gassing with CO2-enriched air, reduced immersion frequency, vessel size and culture time on total phenolic and flavonoid content and free radical scavenging effect of the methanolic extracts was measured. From the TIS-culture of C. citratus, seven compounds were isolated and identified as caffeic acid (1), chlorogenic acid (2), neochlorogenic acid (3), p-hydroxybenzoic acid (4), p-hydroxybenzoic acid 3-O-beta-D-glucoside (5), glutamic acid (6) and luteolin 6-C-fucopyranoside (7). The occurrence of compounds 1-7 and their variability in C. citratus grown under different TIS conditions was determined by HPLC. The free radical scavenging effect of the methanolic extract and compounds was measured by the discoloration of the free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH). The main metabolites in 6- and 8-week-old cultures, both in 5 and 10 1 vessels, were chlorogenic acid (2) (100-113 mg%) and neochlorogenic acid (3) (80-119 mg%), while in the cultures with CO2-enriched air and reduced immersion frequency the main compound detected in the extracts was glutamic acid (6) (400 and 670 mg% for the green and white biomass and 619 and 630 mg% for the green and white biomass, respectively). The most active compounds, as free radical scavengers, in the DPPH discoloration assay were caffeic acid (1), chlorogenic acid (2), neochlorogenic acid (3) and the flavonoid luteolin 6-C-fucopyranoside (7).     

Analysis of marker compounds with anti‐platelet aggregation effects in mailuoning injection using platelet binding assay combined with HPLC‐DAD‐ESI‐MS and solid‐phase extraction technique

Introduction – Mailuoning is prepared from a traditional formula of Chinese medicines and widely used as an antithrombotic agent. In this study, the platelet binding assay was used as a novel biospecific separation and analysis method to explore its active constituents, which could be considered as marker compounds for quality control. Objective – To establish a rapid and simple method to predict marker compounds in herbal medicine injection and evaluate the effects of those compounds. Material and methods – Platelets were used to bind and separate constituents. Binding constituents were analysed and taken as potential active compounds for further evaluation. Solid‐phase‐extraction was adopted to improve sensitivity. HPLC‐DAD and ESI‐MS were used to determine the binding constituents. Results – Five compounds were extracted through the platelet binding process and identified as neochlorogenic acid, caffeic acid, isochlorogenic acid and their isomers. Caffeic acid was selected for the flow cytometric assay to test its effect on platelets activation, which was determined by CD62P (P‐selectin) expression. The results indicated that caffeic acid could significantly inhibit platelet activation while chlorogenic acid did not. Conclusion – Caffeic acid could be considered as a marker compound of Mailuoning injection due to its anti‐platelet effect. The study also suggested that platelet binding assay combined with some preconcentration technique could be efficiently used to predict anti‐platelet compounds in complicated herbal medicines. Copyright © 2010 John Wiley & Sons, Ltd.     

Effects of plant-derived flavonoids and polyphenolic acids on the activity of mutagens from cooked food

The ability of 3 plant flavonoids (morin, myricetin and quercetin) and 4 polyphenolic acids (caffeic acid, chlorogenic acid, ellagic acid and ferulic acid) to inhibit the genotoxic effects of a number of cooked-food mutagens (IQ, MeIQ, MeIQx, Trp-P-1 and Trp-P-2), was investigated in a bacterial mutation assay using Salmonella typhimurium TA98 as indicator and hepatic S9 mixes from either SWR mice or Syrian hamster as metabolic activating systems. Although the polyphenolic acids failed to have an effect, the flavonoids generally inhibited IQ, MeIQ, MeIQx and Trp-P-1 induced mutagenesis in a dose-dependent manner, irrespective of the source of S9. This was not the case with Trp-P-2 where the flavonoids were only observed to inhibit when SWR mouse S9 but not Syrian hamster S9 was used. Of the 3 compounds, myricetin and quercetin were superior to morin in their inhibitory capacity.     

Antimutagenicity of mono-, di-, and tricaffeoylquinic acid derivatives isolated from sweetpotato (Ipomoea batatas L.) leaf

The caffeoylquinic acid derivatives, 3-mono-O-caffeoylquinic acid (chlorogenic acid, ChA), 3,4-di-O-caffeoylquinic acid (3,4-diCQA), 3,5-di-O-caffeoylquinic acid (3,5-diCQA), 4,5-di-O-caffeoylquinic acid (4,5-diCQA) and 3,4,5-tri-O-caffeoylquinic acid (3,4,5-triCQA), and caffeic acid (CA) were isolated from the sweetpotato (Ipomoea batatas L.) leaf. We examined the antimutagenicity of these caffeoylquinic acid compounds to promote new uses of the sweetpotato leaf. These caffeoylquinic acid derivatives effectively inhibited the reverse mutation induced by Trp-P-1 on Salmonella typhimurium TA 98. The antimutagenicity of these derivatives was 3,4,5-triCQA > 3,4-diCQA = 3,5-diCQA = 4,5-diCQA > ChA in this order. There was no difference in the antimutagenicity of all dicaffeoylquinic acid derivatives. A comparison of the activities and structures of these compounds suggested that the number of caffeoyl groups bound to quinic acid played a role in the antimutagenicity of the caffeoylquinic acid derivatives. The sweetpotato leaves contained distinctive polyphenolic components with a high content of mono-, di-, and tricaffeoylquinic acid derivatives and could be a source of physiological functions.     

Molecular modifications on carboxylic acid derivatives as potent histone deacetylase inhibitors: Activity and docking studies

In the light of known HDAC inhibitors, 33 carboxylic acid derivatives were tested to understand the structural requirements for HDAC inhibition activity. Several modifications were applied to develop the structure–activity relationships of carboxylic acid HDAC inhibitors. HDAC inhibition activities were investigated in vitro by using HeLa nuclear extract in a fluorimetric assay. Molecular docking was also carried out for the human HDAC8 enzyme in order to predict inhibition activity and the 3D poses of inhibitor–enzyme complexes. Of these compounds, caffeic acid derivatives such as chlorogenic acid and curcumin were found to be highly potent compared to sodium butyrate, which is a well-known HDAC inhibitor.     

Phenolic compounds induced by <Emphasis Type="Italic">Bemisia tabaci</Emphasis> and <Emphasis Type="Italic">Trialeurodes vaporariorum</Emphasis> in <Emphasis Type="Italic">Nicotiana tabacum</Emphasis> L. and their relationship with the salicylic acid signaling pathway

Changes in the levels of secondary compounds can trigger plant defenses. To identify phenolic compounds induced by Bemisia tabaci Middle East-Asia Minor 1 (MEAM1) in tobacco (Nicotiana tobacco L.), the content changes of 11 phenolic compounds in plants infested by B. tabaci MEAM1 or Trialeurodes vaporariorum were compared. The chlorogenic acid, catechin, caffeic acid, p-coumaric acid, rutin, and ferulic acid contents in B. tabaci MEAM1-infested tobacco plants increased significantly, having temporal and spatial effects, compared with uninfested control and T. vaporariorum infested plants. The contents were 4.10, 2.84, 2.25, 3.81, 1.46, and 1.91 times higher, respectively, than those in the control. However, a T. vaporariorum nymphal infestation just caused smaller chlorogenic acid, catechin, caffeic acid, and rutin contents increase, which were 2.33, 2.13, 1.59, and 3.19 times higher, respectively, than those in the control. In B. tabaci MEAM1 third-instar nymph-infested plants, chlorogenic acid, catechin, caffeic acid, and rutin increased more significantly in systemic than in local leaves. Salicylate-deficient plants inhibited the induction of the content of 10 phenolic compounds, but not caffeic acid, after a B. tabaci MEAM1 nymphal infestation. Thus, the elevated levels of phenolic compounds induced by B. tabaci MEAM1 were correlated with the salicylic acid signaling pathway and induced the responses of defense-related phenolic compounds.     

Inhibitory effect of phenolic compounds on aflatoxin B1 metabolism and induced mutagenesis

The interaction between phenolic compounds and the food-borne carcinogenic mycotoxin, aflatoxin B₁ (AFB₁), was examined. 6 phenolic compounds (gallic acid, chlorogenic acid, caffeic acid, dopamine, p-hydroxybenzoic acid and salicyclic acid) inhibited AFB₁-induced mutagenesis in Salmonella typhimurium strain TA98 in a suspension assay in the presence of rat-liver microsomes (S9). The inhibitory effect was observed when the phenolic compound and the mutagen (AFB₁ plus S9) were administered concurrently, but not when exposure to the mutagen was followed by the phenolic compound. The concentrations of the phenolic compounds used were not mutagenic to S. typhimurium strain TA98 and had no effect on the survival of the bacteria. The inhibition of AFB₁ metabolism was studied using high-pressure liquid chromatography. Increasing the concentration of all 6 phenolic compounds resulted in a dose-dependent reduction of both major AFB₁ metabolite peaks. The results are consistent with the hypothesis that (1) the phenolic compounds do not react covalently with AFB₁, and (2) the inhibitory effect of phenolic compounds on AFB₁-induced mutagenesis may be due to the inhibition of the activation enzymes.     

Drastic effect of several caffeic acid derivatives on the induction of heme oxygenase-1 expression revealed by quantitative real-time RT-PCR

Among antioxidative polyphenols, caffeic acid esters such as caffeic acid phenethyl ester (CAPE) and chlorogenic acid are contained in propolis, vegetables and coffee. In this study, we compared the efficacy of some polyphenols on the activation level of a cytoprotective heme oxygenase-1 (HO-1) gene in RAW264.7 mouse macrophage cells using quantitative real-time RT-PCR. The quantitative study revealed a variety of activation level of HO-1 gene by the chemicals. CAPE and caffeic acid ethyl ester (CAEE) at the final concentration of 2 muM drastically activated the HO-1 gene to 39.2-fold and 20.1-fold, respectively. Curcumin, structurally related with caffeic acid and an element of turmeric, induced the HO-1 gene to 5.8-fold. In contrast, no activation was observed by other caffeic acid esters such as chlorogenic acid and rosmarinic acid. Higher concentrations were necessary for the activation by an antioxidant cysteamine and the electrophile diethyl maleate. Although the inducible activities of CAPE and chlorogenic acid were distinctly different, they showed similar reductive capacities when determined by cyclic voltammetry. These results show that the drastic activation of HO-1 gene by CAPE and CAEE is dependent upon their chemical structures, rather than the reductive activity of polyphenols, possibly reflecting the physiological effects of the nutritional elements.     

Quinyl esters and glucose derivatives of hydroxycinnamic acids during growth and ripening of tomato fruit

Quinyl esters of hydroxycinnamic acids usually occur in greater abundance than their corresponding glucose esters in tomato fruits. During fruit growth and ripening, the predominant derivatives of hydroxycinnamic acids were found to be chlorogenic acid (76%) and the glucosides (84%) respectively. The variations in the ratio of Benedict-reactive (chlorogenic acid) and non-reactive compounds (mainly caffeic acid glucoside) are discussed in relation to their possible role in the regulation of fruit growth and maturation.     

Anthocyanase and Anthocyanins Occurring in Eggplant,Solarium melongena L.

From the eggplant fruits, chlorogenic acid, neochlorogenic acid and caffeic acid have been isolated and identified. Enzymic experiments show that their O-dihydroxyphenolic compounds can be the browning substrates in the fruit flesh, on the other hand chlorogenic acid accelerates the decoloration of nasunin (delphinidin-glycoside) and enables to decolorize pelargonidin-3-glucoside by the anthocyanase.     

HPLC同时测定大叶冬青叶中10种多酚成分的含量及抗氧化活性研究

建立HPLC同时测定大叶冬青叶中新绿原酸、绿原酸、隐绿原酸、咖啡酸、对羟基肉桂酸、芦丁、异槲皮苷、异绿原酸B、异绿原酸A和异绿原酸C 10种多酚类化合物的定量分析方法,研究不同产地及不同采收时期大叶冬青叶中10种多酚类化合物的含量差异及其抗氧化活性。采用HPLC测定大叶冬青叶50%甲醇提取液中10种多酚类成分的含量,并选用DPPH法对其抗氧化活性进行初步探索。结果表明,10种多酚类化合物分离效果较好,标准曲线在检测范围内具有良好的线性(r>0.999 5),平均加样回收率在96.58%～112.03%,RSD<4%(n=6)。大叶冬青叶50%甲醇提取液抗氧活性良好。本实验建立的方法快速、准确、重复性好,可用于同时测定大叶冬青叶中新绿原酸、绿原酸、隐绿原酸、咖啡酸、对羟基肉桂酸、芦丁、异槲皮苷、异绿原酸B、异绿原酸A、异绿原酸C 10种成分的含量;不同产地、不同采收时期大叶冬青叶中10种多酚类化合物含量存在一定差异;不同来源大叶冬青叶50%甲醇提取液抗氧化能力具有明显差异。     

Comparison of the phenolic composition of fruit juices by single step gradient HPLC analysis of multiple components versus multiple chromatographic runs optimised for individual families

After minimal sample preparation, two different HPLC methodologies, one based on a single gradient reversed-phase HPLC step, the other on multiple HPLC runs each optimised for specific components, were used to investigate the composition of flavonoids and phenolic acids in apple and tomato juices. The principal components in apple juice were identified as chlorogenic acid, phloridzin, caffeic acid and p-coumaric acid. Tomato juice was found to contain chlorogenic acid, caffeic acid, p-coumaric acid, naringenin and rutin. The quantitative estimates of the levels of these compounds, obtained with the two HPLC procedures, were very similar, demonstrating that either method can be used to analyse accurately the phenolic components of apple and tomato juices. Chlorogenic acid in tomato juice was the only component not fully resolved in the single run study and the multiple run analysis prior to enzyme treatment. The single run system of analysis is recommended for the initial investigation of plant phenolics and the multiple run approach for analyses where chromatographic resolution requires improvement.     

Study of the causes of direct-acting mutagenicity in coffee and tea using the Ara test in Salmonella typhimurium

The mutagenic activities of 6 of the chemicals identified in coffee solutions were assayed with the Salmonella Ara test, under experimental conditions optimized for coffee mutagenicity. Caffeine was the only non-mutagenic compound. Among the other 5 chemicals, hydrogen peroxide was the strongest mutagen and chlorogenic acid the weakest; methylglyoxal, glyoxal and caffeic acid exhibited intermediate mutagenicities. The minimal mutagenic doses of these components correlated negatively with their relative concentrations in coffee. It was concluded that chlorogenic acid, caffeic acid, glyoxal and methylglyoxal cannot contribute alone to the mutagenicity of coffee in the Ara test, since their minimal mutagenic concentrations were much higher than their respective levels in the coffee samples assayed. By contrast, 40-60% of the mutagenic activity in coffee and also in tea could be attributed to their H2O2 contents. Catalase abolished more than 95% of the mutagenic activity of coffee, as detected by the Ara test. A similar sensitivity to catalase has been reported by other authors in relation to the coffee mutagenicity identified by the Salmonella His test. Nevertheless, the results presented in this paper suggest that the Ara forward and the His reverse mutation tests are sensitive to the mutagenicity of different constituents in coffee solutions. We propose that the His test, sensitive at high coffee doses, mainly recognizes the mutagenicity of methylglyoxal, whilst the Ara test, sensitive at low coffee doses, mainly detects the mutagenic activity of hydrogen peroxide. The data reported also suggest that the direct-acting mutagenicity(ies) detected by the Ara test in tea solutions is (are) based on similar, if not identical, mechanisms.