The role of phenolic compounds in disease resistance in geranium

The present study was conducted in the hill station of G B Pant University of Agriculture and Technology, Ranichauri, Uttarakhand, which is known for its diversity in medicinal and aromatic plants. The plant geranium, also known as rose or lemon geranium is highly valued for its essential oil which is used in the cosmetic and preferring industries. The plant suffers due to stem and root rot both during summer and winter seasons. In the present study, geranium plants showed maximum stem rot incidence (60.55%) and plant mortality (17.20%) during the winter season, whereas in summer the crops showed maximum root rot and wilt complex incidence (38.33%) with plant mortality up to (12.22%). The average stem rot mortality was comparatively low (16–20%) in summer but increased to 18–26% in winter crop. Several phenolic acids such as as tannic, gallic, caffeic, ferulic and benzoic were detected by using high performance liquid chromatography (HPLC) in variable amounts in these plants. The disease intensity varied from 97.77 to 92.46% from season to season. The significance of the phenolic compounds is discussed in relation to disease prevalence.     

DNA-breaking versus DNA-protecting activity of four phenolic compounds in vitro

Given the paradoxical effects of phenolics in oxidative stress, we evaluated the relative pro-oxidant and antioxidant properties of four natural phenolic compounds in DNA nicking. The phenolic compounds differed dramatically in their ability to nick purified supercoiled DNA, with the relative DNA nicking activity in the order: 1,2,4-benzenetriol (100% nicking) > gallic acid > caffeic acid > gossypol (20% nicking). Desferrioxamine (0.02 mM) decreased DNA strand breakage by each phenolic, most markedly with gallate (85% protection) and least with caffeic acid (26% protection). Addition of metals accelerated DNA nicking, with copper more effective (～5-fold increase in damage) than iron with all four phenolics. Scavengers revealed the participation of specific oxygen-derived active species in DNA breakage. Hydrogen peroxide participated in all cases (23–90%). Hydroxyl radicals were involved (32–85%), except with 1,2,4-benzenetriol. Superoxide participated (81–86%) with gallic acid and gossypol, but not with caffeic acid or 1,2,4-benzenetriol. With 1,2,4-benzenetriol, scavengers failed to protect significantly except in combination. Thus, in the presence of desferrioxamine, catalase or superoxide dismutase inhibited almost completely. When DNA breakage was induced by Fenton's reagent (ascorbate plus iron) the two catechols (caffeic acid and gossypol) were protective, whereas the two triols (1,2,4-benzenetriol and gallic acid) exacerbated damage.     

Silene vulgaris subsp. macrocarpa leaves and roots from Morocco: assessment of the efficiency of different extraction techniques and solvents on their antioxidant capacity,brine shrimp toxicity and phenolic characterization

Abstract

This study was undertaken to investigate the effect of various solvents and techniques on the extractability of antioxidant compounds, particularly phenolics, from leaves and roots of Silene vulgaris subsp. macrocarpa grown wild in Morocco. Maceration and hot extraction with methanol or water and Soxhlet ethanol extraction were utilized. Aimed at establishing the potential safety of the extracts, Artemia salina lethality bioassay was performed. All the extracts were found to be non-toxic, except for the leaf Soxhlet ethanol. The antioxidant potential of the extracts was evaluated in vitro by DPPH, reducing power, and ferrous ions chelating activity assays. The leaf extracts displayed noticeable radical scavenging and chelating activities, and maceration with methanol (Mac-MeOH) resulted the most suitable extraction method for an effective recovery of antioxidants; further, the root Mac-MeOH extract demonstrated good chelating properties (IC₅₀ = 335.49?±?0.70?µg/mL). Thus, leaf and root Mac-MeOH extracts were subjected to phytochemical investigations. The total phenolic, flavonoid and condensed tannin content was determined spectrophotometrically. Thirteen polyphenolic compounds were positively identified, by HPLC-PDA-ESI-MS, in the leaf extract for the first time, with p-coumaric acid derivatives being the most abundant ones (81%), whereas only catechin and procyanidin B1 were found in the root extract.     

Antibacterial activity of wine phenolic compounds and oenological extracts against potential respiratory pathogens

Aims: To investigate the effect of seven wine phenolic compounds and six oenological phenolic extracts on the growth of pathogenic bacteria associated with respiratory diseases (Pseudomonas aeruginosa, Staphylococcus aureus, Moraxella catarrhalis, Enterococcus faecalis, Streptococcus sp Group F, Streptococcus agalactiae and Streptococcus pneumoniae). Methods and Results: Antimicrobial activity was determined using a microdilution method and quantified as IC₅₀. Mor. catarrhalis was the most susceptible specie to phenolic compounds and extracts. Gallic acid and ethyl gallate were the compounds that showed the greatest antimicrobial activity. Regarding phenolic extracts, GSE (grape seed extract) and GSE‐O (oligomeric‐rich fraction from GSE) were the ones that displayed the strongest antimicrobial effects. Conclusions: Results highlight the antimicrobial properties of wine phenolic compounds and oenological extracts against potential respiratory pathogens. The antimicrobial activity of wine phenolic compounds was influenced by the type of phenolic compounds. Gram‐negative bacteria were more susceptible than Gram‐positive bacteria to the action of phenolic compounds and extracts; however, the effect was species‐dependent. Significance and Impact of Study: The ability to inhibit the growth of respiratory pathogenic bacteria as shown by several wine phenolic compounds and oenological extracts warrants further investigations to explore the use of grape and wine preparations in oral hygiene.     

Effect of cadmium on the phenolic compounds formation in the callus cultures derived from various organs of the tea plant

The effects of cadmium (6.3 × 10^?5 M or 10.6 × 10^?5 M) on the growth of tea plant (Camellia sinensis L.) callus cultures derived from leaves, stems, and roots and on the formation, in these cultures, of phenolic compounds, including flavans and lignin, which are characteristic of the tea plant, were investigated. In the calli derived from leaves and stems, cadmium treatment decreased the biomass increment, while in the calli derived from roots, growth characteristics remained at the control level. Under the effect of cadmium, the content of phenolic compounds, including flavans, in the leaf calli decreased, while in the stem and root calli, it either increased (at the cadmium concentration of 6.3 × 10^?5 M), or was close to a control one (at the cadmium concentration of 10.6 × 10^?5 M). The lignin content in the root and stem calli increased, but it did not change in the leaf calli. All this data demonstrate that the cadmium-induced changes in phenolic metabolism of the tea plant callus culture depended both on the cadmium concentration in the medium and on the origin of calli.     

Influence of epigallocatechin gallate and phenolic compounds from green tea on the growth of Oenococcus oeni

Aims: To investigate the effect of phenolic compounds on the growth of Oenococcus oeni. Methods and Results: Oenococci are usually grown in media often supplemented with complex additives such as tomato juice. In order to improve our knowledge about the growth requirements of oenococci, we added several juices and leaf extracts such as green tea to the culture media and screened them for growth‐stimulating substances to substitute complex supplements such as juices by more defined components. We found that also green tea could cause a growth stimulation of Oenococcus oeni strain B2. Conclusions: Further experiments showed that the stimulating effect was as a result of the phenolic compounds of green tea, especially epigallocatechin gallate (EGCG). On the other hand, EGCG could also inhibit the growth of O. oeni strain B2 just depending on its concentration. Significance and Impact of the Study: Individual catechins should have a minor influence on the growth of oenococci during wine making as their concentration in grapes is <30 mg kg^?1 grape. Whether there is a synergistic effect of the different catechins in wine has to be investigated.     

Effect of phenolic compounds on glucose-6-phosphate dehydrogenase isoenzymes

Effector studies with two isoenzymes (I and IV) of glucose-6-phosphate dehydrogenase (G6PDH) from tobacco suspension culture WR-132 revealed that chlorogenic acid, at 0.4 mM, inhibited both isoenzymes almost 100%, with the inhibition decreasing as the concentration of the acid was reduced. At 0.3 and 0.4 mM, the coumarin glucosides scopolin and esculin were inhibitory, whereas their aglucones scopoletin and esculetin were less inhibitory, and at low concentrations of glucose-6-phosphate (G6P), the latter two were actually stimulatory for G6PDH I. Of the possible effectors studied, only scopoletin and esculetin exhibited a significant activation of G6PDH I under these conditions. However, with G6PDH IV these two effectors do not show the same marked activation at the low G6P concentrations. The phenolic acids, caffeic and ferulic, were less inhibitory than the coumarins tested. The activation of G6PDH I by scopoletin, a compound which accumulates in tobacco under certain stress conditions, gives a possible clue as to the resulting enhanced activity of the hexose monophosphate pathway that has been reported for some plants subjected to stress conditions.     

Inactivation of oenological lactic acid bacteria (Lactobacillus hilgardii and Pediococcus pentosaceus) by wine phenolic compounds

Aims:  To investigate the inactivation properties of different classes of phenolic compounds present in wine against two wine isolates of Lactobacillus hilgardii and Pediococcus pentosaceus , and to explore their inactivation mechanism.
Methods and Results:  After a first screening of the inactivation potency of 21 phenolic compounds (hydroxybenzoic and hydroxycinnamic acids, phenolic alcohols, stilbenes, flavan-3-ols and flavonols) at specific concentrations, the survival parameters (MIC and MBC) of the most active compounds were determined. For the L. hilgardii strain, the flavonols morin and kaempferol showed the strongest inactivation (MIC values of one and 5 mg l⁻¹, and MBC values of 7·5 and 50 mg l⁻¹, respectively). For the P. pentosaceus strain, flavonols also showed the strongest inactivation effects, with MIC values between one and 10 mg l⁻¹ and MBC values between 7·5 and 300 mg l⁻¹. Observations by epifluorescence and scanning electron microscopy revealed that the phenolics damaged the cell membrane and promoted the subsequent release of the cytoplasm material into the medium.
Conclusions:  The antibacterial activity of wine phenolics against L. hilgardii and P. pentosaceus was dependent on the phenolic compound tested, and led not only to bacteria inactivation, but also to the cell death.
Significance and Impact of the Study:  New information about the inactivation properties of wine lactic acid bacteria by phenolic compounds is presented. It opens up a new area of study for selecting/obtaining wine phenolic preparations with potential applications as a natural alternative to SO₂ in winemaking.     

生物质催化转化制备呋喃基化学品和酚类化合物

生物质转化制备精细化学品是解决石油能源危机的重要途径之一。其中,纤维素及半纤维素转化合成呋喃基化学品与木质素转化制酚类化合物是主要的反应路线,特别是借助催化技术加速生物质转化更是当今化学领域的研究重点;依据催化反应体系的不同,对近年来用于生物质催化转化的反应媒介以及催化剂研究进展进行了综述,并对未来生物质催化转化研究方向的发展前景进行了展望。     

Effect of phenolic compounds on the co-metabolism of citric acid and sugars by Oenococcus oeni from wine

AIMS: The goal of this study was to examine the growth of Oenococcus oeni in the presence of phenolic compounds under wine conditions and to see how these compounds affect bacterial metabolism. METHODS AND RESULTS: Phenolic compounds have been added to a basal medium that simulates the composition of wine. Fifty milligrams per litre or more of phenolic compounds stimulated bacterial growth. Oenococcus oeni seemed to use citric acid and trehalose, if they were present, before glucose and fructose. Citrate was completely exhausted in three days and the yield of acetate was higher when phenolic compounds were present. CONCLUSIONS: Phenolic compounds reduced the rate of sugar consumption and enhanced citric acid consumption, increasing the yield of acetic acid. SIGNIFICANCE AND IMPACT OF THE STUDY: This study allows a better knowledge of co-metabolism of citric acid and sugars by O. oeni in the presence of phenolic compounds of wine.     

Inhibition ofCandida albicans andStaphylococcus aureus by phenolic compounds from the terrestrial cyanobacteriumNostoc muscorum

Phenolic compounds were determined in methanolic extract from the algal mass of aNostoc muscorum culture. Bioassays with two human pathogens,Candida albicans andStaphylococcus aureus indicated that algal phenolic compounds evoked significant growth inhibition for both species (89.1% and 88.2%, respectively). It is suggested that this strong inhibitory effect is of potential medicinal value.     

Inhibitory effects of some phenolic compounds on the activities of carbonic anhydrase: from in vivo to ex vivo

Carbonic anhydrase (CA) inhibitors have been used for more than 60 years for therapeutic purposes in many diseases table such as in medications against antiglaucoma and as diuretics. Phenolic compounds are a new class of CA inhibitor. In our study, we tested the effects of arachidonoyl dopamine, 2,4,6-trihydroxybenzaldehyde and 3,4-dihydroxy-5-methoxybenzoic acid on esterase and the CO₂-hydratase activities of CA I and II isozymes purified from in vivo to ex vivo. The K_i values of arachidonoyl dopamine, 2,4,6-trihydroxybenzaldehyde and 3,4-dihydroxy-5-methoxybenzoic acid were 203.80, 1170.00 and 910.00?μM, respectively for hCA I and 75.25, 354.00 and 1510.00?μM, respectively for hCA II. Additionally, IC₅₀ values from in vivo studies were found to be in the range of 173.25–1360.0?μM for CA I and II, respectively, using CO₂-hydratase activity methods. These results demonstrated that phenolic compounds used in in vivo studies could be used in different biomedical applications to inhibit approximately 30% of the CO₂-hydratase activity of the total CA enzyme of rat erythrocytes.     

Production of phenolic compounds in callus cultures of tea plant under the effect of 2,4-D and NAA

The effect of hormone-like compounds at different concentrations: 2,4-D (2 × 10^?6; 2 × 10^?5; and 2 × 10^?4M) and 1-NAA (2 × 10^?7; 2 × 10^?6; 2 × 10^?5; 4 × 10^?5, and 6 × 10^?5 M) on the growth and production of phenolic compounds, including flavans and lignin, was investigated in callus culture of tea plant (Camellia sinensis L., a highly productive strain IFR ChS-2). The growth of the culture was vigorous, and production of phenolic compounds therein was efficient in the medium containing 2 × 10^?5 M 2,4-D. Substitution of 1-NAA for 2,4-D in all the cases decelerated the growth of the culture. These changes were more pronounced when 2 × 10^?7 and 2 × 10^?6 M 1-NAA was used; in this case, biomass accumulation decreased by 1.5–2.0 times as compared with control material growing on the medium with 2 × 10^?5 M 2,4-D. In the presence of 1-NAA, the content of total soluble phenolic compounds and flavans in the calli rose by 30% on the average as compared with control material. Accumulation of lignin remained essentially the same. Therefore, the replacement of 2,4-D with 1-NAA in the nutrient medium used for the growing of highly productive strain of tea plant callus did not induce considerable changes in its ability to produce phenolic compounds.     

Wine phenolic compounds influence the production of volatile phenols by wine-related lactic acid bacteria

Aims: To evaluate the effect of wine phenolic compounds on the production of volatile phenols (4‐vinylphenol [4VP] and 4‐ethylphenol [4EP]) from the metabolism of p‐coumaric acid by lactic acid bacteria (LAB). Methods and Results: Lactobacillus plantarum, Lactobacillus collinoides and Pediococcus pentosaceus were grown in MRS medium supplemented with p‐coumaric acid, in the presence of different phenolic compounds: nonflavonoids (hydroxycinnamic and benzoic acids) and flavonoids (flavonols and flavanols). The inducibility of the enzymes involved in the p‐coumaric acid metabolism was studied in resting cells. The hydroxycinnamic acids tested stimulated the capacity of LAB to synthesize volatile phenols. Growth in the presence of hydroxycinnamic acids, especially caffeic acid, induced the production of 4VP by resting cells. The hydroxybenzoic acids did not significantly affect the behaviour of the studied strains. Some of the flavonoids showed an effect on the production of volatile phenols, although strongly dependent on the bacterial species. Relatively high concentrations (1 g l^?1) of tannins inhibited the synthesis of 4VP by Lact. plantarum. Conclusions: Hydroxycinnamic acids were the main compounds stimulating the production of volatile phenols by LAB. The results suggest that caffeic and ferulic acids induce the synthesis of the cinnamate decarboxylase involved in the metabolism of p‐coumaric acid. On the other hand, tannins exert an inhibitory effect. Significance and Impact of the Study: This study highlights the capacity of LAB to produce volatile phenols and that this activity is markedly influenced by the phenolic composition of the medium.     

The effect of quinoid and phenolic compounds on urease and dehydrogenase activity and nitrification in soil

Summary 1,4-Naphthoquinone; 2-methyl-1,4-napthoquinone; 2,3-dichlorohydroquinone; 4,6-di-tert.butyl-o-benzoquinone; 4,6-di-tert.butylpyrocatechol and 4-tert.butylpyrocatechol at concentrations of 10 and 20 ppm inhibit mineralization of urea N by reducing urease activity and/or nitrification in soils. Coating of urea with these chemicals was more effective than direct application to the soil. There was no adverse effect of any of the chemicals either on germination or on the growth of wheat plants at concentrations of 20 and 50 ppm added to soil.     

A chemotaxonomical study of someBoraginaceae: pyrrolizidine alkaloids and phenolic compounds

By means of thin layer chromatography pyrrolizidine alkaloids and phenolic compounds in some members of the familyBoraginaceae, subfamiliesHeliotropioideae andBoraginoideae, were studied. FromOmphalodes verna a main alkaloid was isolated with an isoretronecanol (or stereoisomeric) nucleus. The chemotaxonomical model ofTétényi forBoraginaceae based on fatty acids is generally supported, but relationships betweenHeliotropioideae andCynoglosseae appear to be closer, suggesting parallel developments from common ancesters.     

Antibacterial activity of sphagnum acid and other phenolic compounds found in Sphagnum papillosum against food-borne bacteria

Aims:  To identify the phenolic compounds in the leaves of Sphagnum papillosum and examine their antibacterial activity at pH appropriate for the undissociated forms.
Methods and Results:  Bacterial counts of overnight cultures showed that whilst growth of Staphylococcus aureus 50084 was impaired in the presence of milled leaves, the phenol-free fraction of holocellulose of S. papillosum had no bacteriostatic effect. Liquid chromatography–mass spectrometry analysis of an acetone–methanol extract of the leaves detected eight phenolic compounds. Antibacterial activity of the four dominating phenols specific to Sphagnum leaves, when assessed in vitro as minimal inhibitory concentrations (MICs), were generally >2·5 mg ml⁻¹. MIC values of the Sphagnum- specific compound 'sphagnum acid' [ p -hydroxy-β-(carboxymethyl)-cinnamic acid] were >5 mg ml⁻¹. No synergistic or antagonistic effects of the four dominating phenols were detected in plate assays.
Conclusions:  Sphagnum -derived phenolics exhibit antibacterial activity in vitro only at concentrations far in excess of those found in the leaves.
Significance and Impact of the Study:  We have both identified the phenolic compounds in S. papillosum and assessed their antibacterial activity. Our data indicate that phenolic compounds in isolation are not potent antibacterial agents and we question their potency against food-borne pathogens.     

Effect of different conditioning treatments on total phenolic content and antioxidant activities in two Sargassacean species: Comparison of the frondose Sargassum muticum (Yendo) Fensholt and the cylindrical Bifurcaria bifurcata R. Ross

The effects of different conditioning treatments (fresh, freezing, freeze‐drying, oven‐drying and greenhouse‐drying) on the total phenolic content (TPC) and antioxidant activities of two brown algae, Sargassum muticum and Bifurcaria bifurcata, were investigated and compared. Phenolic compounds were extracted in a methanol/water (50:50) solution, and TPC was measured by the colorimetric Folin‐Ciocalteu assay. Antioxidant activity was assessed by the DPPH (2, 2‐diphenyl‐1‐picrylhydrazyl) radical scavenging assay and the β‐carotene bleaching method. The dried seaweeds showed lower phenolic contents and lower antioxidant capacities than the fresh and frozen ones, which suggests that the phenolic content and antioxidant activities are decreased by the drying treatments, especially, oven‐ and greenhouse‐drying. Relationships between TPC, antioxidant properties and conditioning treatments are discussed.     

VA菌根化杉树苗抗酚能力的研究

利用 Ｖ Ａ 菌根化杉树苗进行了加酚水培和土培,试验结果表明, Ｖ Ａ 菌根化杉树苗对邻香草醛,对羟基苯甲酸、阿魏酸等酚类物质有明显的耐受性