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.     

Antioxidant activity and phenol content of Crithmum maritimum L. leaves

Sea fennel (Crithmum maritimum L.) is an edible halophyte with various economical interests because of its high secondary metabolite content. However, little is known about water-soluble compounds in that species. Here, we have studied major solutes in C. maritimum leaves. Among these solutes, carbohydrates (sucrose, glucose) were the most abundant, followed by organic acids (malate and quinate) and a phenolic compound never described in a halophyte before: chlorogenic acid (CGA). Total phenols and chlorogenic acid contents were followed throughout one year, as well as antioxidant activity, in two populations of C. maritimum growing in contrasting habitats: sand hills and cliffs. Sea fennel leaves appeared to be rich in phenolic compounds, particularly in chlorogenic acid. On that point, differences between the two populations were found, sand hill plants accumulating more CGA than those growing on cliffs. Moreover, the former presented a higher radical-scavenging activity, and the two observations were positively correlated. These results indicate that sea fennel can be considered as a valuable source of antioxidant products, especially of chlorogenic acid.     

Phenolic compounds of Sophora flavescens Soland. of Russian origin

A qualitative composition and a quantitative content of phenolic compounds of underground and above-ground parts of Sophora flavescens Soland. (the Fabaceae family) growing in Russia (Transbaikalia, Primorsky Krai, Aga Buryat Autonomous District) were studied. Eleven compounds were isolated from the roots and rhizomes: kushenol A, isokurarinone, kuraridine, sophoraflavanone G, kurarinone, isoxanthohumol, umbeliferon, and, for the first time, scopoletin, ferulic, caffeic, and chlorogenic acids. Ten phenolic compounds were identified in the herb of S. flavescens: cynaroside, cosmosiin, caffeic acid, and, for the first time, apigenin, luteolin, quercetin, umbelliferone, rutin, chlorogenic, and neochlorogenic acids. Dominant compounds in the underground part were kurarinone and sophoraflavanone G, and in the above-ground part, cynaroside and rutin. It was shown that the maximum content of flavonoids in the underground part of S. flavescens was accumulated in the epidermal layers of rhizomes. The dynamics of flavonoids accumulation in S. flavescens was studied.     

Chlorogenic acid biosynthesis in Cestrum poeppigii

The chlorogenic acid content of Cestrum poeppigii, and its ability to form the acid from labelled t-cinnamic acid, was determined at different stages of growth. In contrast to mature plants, young plants showed great seasonal variation in their chlorogenic acid content. The incorporation of radioactivity from t-cinnamic into chlorogenic acid also differed greatly during the growth period. Trapping experiments with caffeic and p-coumaric acids were performed to study the effect of large pools of these acids on the incorporation of t-cinnamic acid-3-[¹⁴C] into chlorogenic acid. The kinetics of incorporation exclude a major role for caffeic acid in the biosynthesis of chlorogenic acid.     

Boron deficiency causes accumulation of chlorogenic acid and caffeoyl polyamine conjugates in tobacco leaves

The effects of boron (B) deficiency on carbohydrate concentrations and the pattern of phenolic compounds were studied in leaves of tobacco plants (Nicotiana tabacum L.). Plants grown under B deficiency showed a notable increase in leaf carbohydrates and total phenolic compounds when compared to controls. The qualitative composition of phenolics was analyzed by HPLC-mass spectrometry. The level of caffeate conjugates (i.e., chlorogenic acid) increased in B-deficient plants. In addition, the accumulation of two caffeic acid amides (N-caffeoylputrescine and putative dicaffeoylspermidine) was observed.     

Oxidation of phenolic compounds by the bifunctional catalase–phenol oxidase (CATPO) from Scytalidium thermophilum

The thermophilic fungus Scytalidium thermophilum produces a novel bifunctional catalase with an additional phenol oxidase activity (CATPO); however, its phenol oxidation spectrum is not known. Here, 14 phenolic compounds were selected as substrates, among which (+)-catechin, catechol, caffeic acid, and chlorogenic acid yielded distinct oxidation products examined by reversed-phase HPLC chromatography method. Characterization of the products by LC-ESI/MS and UV–vis spectroscopy suggests the formation of dimers of dehydrocatechin type B (hydrophilic) and type A (hydrophobic), as well as oligomers, namely, a trimer and tetramer from (+)-catechin, the formation of a dimer and oligomer of catechol, a dimer from caffeic acid with a caffeicin-like structure, as well as trimeric and tetrameric derivatives, and a single major product from chlorogenic acid suggested to be a dimer. Based on the results, CATPO oxidizes phenolic compounds ranging from simple phenols to polyphenols but all having an ortho-diphenolic structure in common. The enzyme also appears to have stereoselectivity due to the oxidation of (+)-catechin, but not that of epicatechin. It is suggested that CATPO may contribute to the antioxidant mechanism of the fungus and may be of value for future food and biotechnology applications where such a bifunctional activity would be desirable.     

Influence of boron toxicity on single phenols of tomato leaves

Summary Leaves of tomato plants grown in a hydroponic culture using a boron toxic solution present a different single phenols composition than those grown using an optimized nutrient solution. The absence of caffeic acid and aesculetin in boron toxic plants at flowering suggests that these compounds can be used as markers for the biochemical diagnosis of boron toxicity in tomato plants.     

Active polyphenolic compounds,nutrient contents and antioxidant capacity of extruded fish feed containing purple coneflower (Echinacea purpurea (L.) Moench.)

The growth of fish is directly dependent on feed composition and quality. Medicinal plants can be added to fish feed as adjuvant therapy for the prevention of fish diseases. The purple coneflower (Echinacea purpurea (L.) Moench.) has been reported to have multiple biological effects, including immunomodulatory and antioxidant activity. The most active compounds of E. purpurea are polyphenols - caffeic acid derivatives: caftaric acid, chlorogenic acid, cynarin, echinacoside and cichoric acid.Due to a relatively limited number of studies on the use of the purple coneflower as a nutritional supplement for fish feeding, extruded fish feed with addition of Echinacea roots was produced. In the feed total phenolic content, selected polyphenol contents, the energetic value, nutrient contents and antioxidant capacity were examined.The results indicate that fish feed with addition of the Echinacea has a great potential to be a good source of natural radical scavengers, for example polyphenols, and nutritive ingredients. Antioxidant properties of feed were well correlated with the coneflower content. The study findings confirmed that high-temperature extrusion-cooking process does not deactivate phenolic antioxidant compounds, which are present both in the Echinacea roots and in the final product. Fish feed with addition of E. purpurea can be used as a nutritional supplement in the prevention of fish diseases caused by oxidative stress.     

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.     

Induced responses of Coffea arabica to attack of Coccus viridis stimulate locomotion of the herbivore

The green scale, Coccus viridis (Green) (Hemiptera: Coccidae), is an insect pest of coffee and several other perennial cultivated plant species. We investigated changes in alkaloid and phenolic contents in coffee plants as a response to herbivory by this insect. Greenhouse‐grown, 11‐month‐old coffee plants were artificially infested with the coccid and compared with control, uninfested plants. Leaf samples were taken at 15, 30, 45, and 60 days after infestation, and high‐performance liquid chromatography was used to identify and quantify alkaloid and phenolic compounds induced by the coccids at each sampling date. Of the compounds investigated, caffeine was the main coffee alkaloid detected in fully developed leaves, and its concentration in infested plants was twice as high as in the control plants. The main coffee phenolics were caffeic and chlorogenic acid, and a significant increase in their concentrations occurred only in plants infested by C. viridis. A positive and significant relationship was found between alkaloid and phenolic concentrations and the infestation level by adults and nymphs of C. viridis. Caffeine and chlorogenic acid applied on coffee leaves stimulated the locomotory activity of the green scale, thus reducing their feeding compared to untreated leaves. This is the first study to show increased levels of coffee alkaloids and phenolics in response to herbivory by scale insects. The elevation of caffeine and chlorogenic acid levels in coffee leaves because of C. viridis infestation seems to affect this generalist insect by stimulating the locomotion of crawlers.     

In vitro antioxidant activity and phenolic contents in methanol extracts from medicinal plants

Antioxidant activities and phenolic contents of 26 species extracts from 20 botanical families grown in north-western Himalaya were investigated. Antioxidant activities were determined using DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging and ferric reducing antioxidant power (FRAP) assays. Total phenolic content (TPC) was determined using a Folin-Ciocalteu assay. Quantitative and qualitative analysis of phenolic compounds was also carried out by reverse phase high performance liquid chromatography (RP-HPLC) using diode array detector (DAD). Major phenolics determined using RP-HPLC in analyzed species were gallic acid, chlorogenic acid, p-hydroxy benzoic acid, caffeic acid, vanillic acid, syringic acid, p-coumaric acid and ferulic acid. Antiradical efficiency (1/EC₅₀) determined using DPPH radical scavenging assay ranged from 0.13 to 5.46. FRAP values ranged from 8.66 to 380.9 μmol Fe(II)/g dw. Similarly, the total phenolic content in the analyzed species varied from 3.01 to 69.96 mg of gallic acid equivalents (GAE)/g dry weight. Gallic acid was found in the majority of the samples, being most abundant compound in Syzygium cumini bark (92.64 mg/100 g dw). Vanillic acid was the predominant phenolic compound in Picrorhiza kurroa root stolen (161.2 mg/100 g dry weight). The medicinal plants with highest antioxidant activities were Taxus baccata and Syzygium cumini. A significant positive correlation, R ²?=?0.9461 and R ²?=?0.9112 was observed between TPC determined using Folin-Ciocalteu method and antiradical efficiency and FRAP values respectively, indicating that phenolic compounds are the major contributor of antioxidant activity of these medicinal plants.     

Induction of phenolic acids and metals in Arachis hypogaea L. plants due to feeding of three lepidopteran pests

The feeding of lepidopteran pests, Amsacta albistriga W., Aproaerema modicella D. and Spilosoma obliqua W., caused feeding stress in the Arachis hypogaea L. plants. As a common defensive response, the plant exhibited variations in the primary and secondary metabolic contents. Groundnut plant antioxidative enzymes such as peroxidase, superoxide dismutase, polyphenol oxidase, catalase and phenyl ammonia lyase exhibited alterations to confer resistance against the pest. Phenolic compounds, namely coumaric acid, chlorogenic acid, resveratrol, epicatechin, ferulic acid and caffeic acid, showed active defensive role in groundnut plant against the pest feeding through their significant presence in Fourier transform infrared spectroscopy, high-performance liquid chromatography and gas chromatography studies. Changes in metal contents like iron, magnesium, zinc, potassium and calcium were also reported through atomic absorption studies, indicating their defensive role against the biotic stress caused on groundnut by the three lepidopteran pests. The present study can further assist in recognizing the importance of these specific phenolic acids and metals of groundnut in its pest management.     

Comparative Study on the Inhibitory Effect of Caffeic and Chlorogenic Acids on Key Enzymes Linked to Alzheimer’s Disease and Some Pro-oxidant Induced Oxidative Stress in Rats’ Brain-In Vitro

This study sought to investigate and compare the interaction of caffeic acid and chlorogenic acid on acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), and some pro-oxidants (FeSO₄, sodium nitroprusside and quinolinic acid) induced oxidative stress in rat brain in vitro. The result revealed that caffeic acid and chlorogenic acid inhibited AChE and BChE activities in dose-dependent manner; however, caffeic acid had a higher inhibitory effect on AChE and BChE activities than chlorogenic acid. Combination of the phenolic acids inhibited AChE and BChE activities antagonistically. Furthermore, pro-oxidants such as, FeSO₄, sodium nitroprusside and quinolinic acid caused increase in the malondialdehyde (MDA) contents of the brain which was significantly decreased dose-dependently by the phenolic acids. Inhibition of AChE and BChE activities slows down acetylcholine and butyrylcholine breakdown in the brain. Therefore, one possible mechanism through which the phenolic acids exert their neuroprotective properties is by inhibiting AChE and BChE activities as well as preventing oxidative stress-induced neurodegeneration. However, esterification of caffeic acid with quinic acid producing chlorogenic acid affects these neuroprotective properties.     

Impact of Plant Phenolics as Semiochemicals on the Performance of <Emphasis Type="Italic">Trichogramma chilonis</Emphasis> Ishii

Phenolic compounds play a major role in the plant defense mechanisms and often offer protection from the feeding herbivore. They also constitute a major chemical component of many agriculturally important crops. We examined the effects of 23 common phenolic acids on the orientation and ovipositional behavior of the egg parasitoid, Trichogramma chilonis Ishii (Hymenoptera: Trichogrammatidae). The study was conducted in order to investigate the function of these compounds in the plant indirect defense. Parasitoids attractions towards the phenolics that are volatile in nature were observed by using culture tube bioassays. In addition in the Y- tube olfactometer experiments, T. chilonis were shown to be attracted towards the treatments of syringic, pyrocatechol, coumaric and quercetin at minimum dose of 10 μg and genistein, chlorogenic, vanillic, chlorobenzoic, sinapic, ellagic, protocatechuic, keampferol, tannic, caffeic, and luteolin at 30 μg and ferulic, epicatechin and gallic acid at 50 μg doses. Further experiments to examine the effect of phenolic compounds on parasitization by T. chilonis females were carried out using petri dish and artificial plant models. Among the tested compounds, syringic acid and quercetin recorded the highest percentage parasitization followed by coumaric acid and pyrocatechol. These results might imply that parasitoid attractant phenolic compounds when induced in engineered plants can further be used as cues by the egg parasitoids with potential application in biocontrol strategies.     

Mosquito repelling activity of compounds occurring inAchillea millefolium L. (asteraceae)

An ethanol extract ofAchillea millefolium L. showed repelling properties against the mosquito,Aedes aegypti L. Prepared fractions from the extract contained several active compounds which were characterized by thin layer chromatography, high performance liquid chromatography, gas chromatography and mass spectroscopy. Of 35 compounds tested, the most active were the nitrogen containing compound stachydrine, the carboxylic acids, caffeic, chlorogenic, and salicylic acids, and the phenolic compound pyrocatechol. These substances are earlier reported to occur inA. millefolium with the exception of pyrocatechol. Some further substances with lower activity were characterized for the first time inA. millefolium, i.e., adenine, ferulic and mandelic acid, and the methyl esters of capryliclinolenic- and undecylenic acid.     

Altitudinal changes in secondary metabolite contents of Hypericum androsaemum and Hypericum polyphyllum

The genus Hypericum (Hypericaceae) has attracted scientific interest as its members have yielded many bioactive compounds. In the present study we investigated the content of hypericin, pseudohypericin, hyperforin, adhyperforin, chlorogenic acid, neochlorogenic acid, caffeic acid, 2,4-dihydroxybenzoic acid, 13,II8-biapigenin, hyperoside, isoquercitrin, quercitrin, quercetin, avicularin, rutin, (+)-catechin and (−)-epicatechin in aerial parts of plants from populations of H. androsaemum L. and H. polyphyllum Boiss. & Bal. from Turkey growing at different altitudes. The plant materials were dried and subsequently assayed for chemical content by HPLC. All the tested compounds were detected in both species at varying levels depending upon the altitude the plants were growing, except for hypercins and rutin which did not accumulate in H. androsaemum. It was observed that overall the compounds were more abundant in plants from higher altitudes. The differences in the levels of the compounds could contribute to the ability of the plants to deal with the abiotic stress of lower temperature and higher ultraviolet (UV)-B radiation which would be greater at higher altitudes compared to lower altitudes.     

Bioavailability of chlorogenic acids following acute ingestion of coffee by humans with an ileostomy

The intestinal absorption and metabolism of 385 μmol chlorogenic acids following a single intake of 200 mL of instant coffee by human volunteers with an ileostomy was investigated. HPLC-MS³ analysis of 0-24 h post-ingestion ileal effluent revealed the presence of 274 ± 28 μmol of chlorogenic acids and their metabolites accounting for 71 ± 7% of intake. Of the compounds recovered, 78% comprised parent compounds initially present in the coffee, and 22% were metabolites including free and sulfated caffeic and ferulic acids. Over a 24 h period after ingestion of the coffee, excretion of chlorogenic acid metabolites in urine accounted for 8 ± 1% of intake, the main compounds being ferulic acid-4-O-sulfate, caffeic acid-3-O-sulfate, isoferulic acid-3-O-glucuronide and dihydrocaffeic acid-3-O-sulfate. In contrast, after drinking a similar coffee, urinary excretion by humans with an intact colon corresponded to 29 ± 4% of chlorogenic acid intake [23]. This difference was due to the excretion of higher levels of dihydroferulic acid and feruloylglycine together with sulfate and glucuronide conjugates of dihydrocaffeic and dihydroferulic acids. This highlights the importance of colonic metabolism. Comparison of the data obtained in the current study with that of Stalmach et al. [23] facilitated elucidation of the pathways involved in post-ingestion metabolism of chlorogenic acids and also helped distinguish between compounds absorbed in the small and the large intestine.     

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.     

The enzymic conversion of hydroxycinnamic acids to p-coumarylquinic and chlorogenic acids in tomato fruits

Two enzymes thought to be involved in the biosynthesis of chlorogenic acid have been separated and purified by ion exchange chromatography and their properties studied. These two enzymes, p-coumarate CoA ligase and hydroxycinnamyl CoA: quinate hydroxycinnamyl transferase, acting together catalyse the conversion of p-coumaric acid to 5′-p-coumarylquinic acid and of caffeic acid to chlorogenic acid. The ligase has a higher affinity for p-coumaric than for caffeic acid and will in addition activate a number of other cinnamic acids such as ferulic, isoferulic and m-coumaric acids but not cinnamic acid. The transferase shows higher activity and affinity with p-coumaryl CoA than caffeyl CoA. It also acts with ferulyl CoA but only very slowly. The enzyme shows high specificity for quinic acid; shikimic acid is esterified at only 2% of the rate with quinic acid and glucose is not a substrate. The transferase activity is reversible and both chlorogenic acid and 5′-p-coumarylquinic acids are cleaved in the presence of CoA to form quinic acid and the corresponding hydroxycinnamyl CoA thioester.     

Isolation of phenolic constituents and characterization of antioxidant markers from sunflower (Helianthus annuus) seed extract

A new compound, benzyl alcohol β-d-apiofuranosyl-(1→6)-β-d-(4-O-caffeoyl) glucopyranoside (1), was isolated from the seed of sunflower (Helianthus annuus), together with eight known phenolic compounds: caffeic acid (2), methyl caffeoate (3), chlorogenic acid (4), 4-O-caffeoylquinic acid (5), 3-O-caffeoylquinic acid (6), methyl chlorogenate (7), 3,5-di-O-caffeoylquinic acid (8), and eriodictyol 5-O-β-d-glucoside (9). Their structures were elucidated on the basis of spectroscopic methods and chemical evidence. The antioxidative effect of the phenolic constituents from the sunflower seeds was also evaluated based on the oxygen-radical absorbance capacity (ORAC), and the fraction containing caffeic acid derivatives showed a high antioxidant potency.