Impact of Continuous Cropping on Soil Phenolic Acid Substances and Research Progress on Continuous Cropping Obstacle Reduction Techniques

At present,long-term continuous cropping in agricultural production has formed a relatively common development trend.With the increase of continuous cropping years,soil phenolic acids are also affected to varying degrees.This paper summarized the effects of continuous cropping on soil phenolic acids and the research progress of continuous cropping obstacle reduction techniques,aiming at providing theoretical basis and technical support for the research of continuous cropping obstacle reduction techniques and promoting the healthy and sustainable development of modern agriculture.

A change of phenolic acids content in poplar leaves induced by methyl sali-cylate and methyl jasmonate

The contents of seven different phenolic acids such as gallic acid, catechinic acid, pyrocatechol, caffeic acid, coumaric acid, ferulic acid and benzoic acid in the poplar leaves （Populus Simonii×Populus Pyramibalis c.v and Populus deltoids） suffocated by Methyl jasmonate （MeJA） and Methyl salicylate （MeSA） were monitored for analyzing their functions in interplant communications by using high-pressure liquid chromatography （HPLC）.The results showed that the contents of phenolic acids had obviously difference in leaves exposed to either MeSA or MeJA.When P.deltoides leaves exposed to MeJA or MeSA, the level of gallic acid, coumaric acid, caffeic acid, ferulic acid and benzoic acid was increased, gallic acid in leaves treated with MeJA comes to a peak at 24 h while to a peak at 12-d having leaves treated with MeSA.When P.Simonii ×P.Pyramibalis c.v leaves were exposed to MeJA or MeSA, the level of gallic acid, pyrocatechol and ferulic acid was increased; The catechinic acid and benzoic acid had a little drop; The caffeic acid and coumaric acid were undetected in both suffocated and control leaves.This changed pattern indicated that MeJA and MeSA can act as airborne signals to induce defense response of plants.

Two New Phenolic Carboxylic Acid Esters from Opuntia vulgaris

Two new phenolic carboxylic acid esters n-butyl eucomate(1) and methyl eucomate (2) and six known compounds eucomic acid(3), 3-β-acetyl-taraxerol (4), friedelin(5),lupenone(6),methyl linoleate(7) and methyl oleate(8) were isolated from the stems of Opuntia vulgaris Mill(Cactaceae). Their structures were determined on the basis of spectral methods. Compounds 3,4,6,7,8 were isolated for the first time from this plant.

Induced Effects of Exogenous Phenolic Acids on Allelopathy of a Wild Rice Accession(Oryza longistaminata,S37)

Four exogenous phenolic acids, including salicylic acid, fumalic acid, p-coumaric acid and p-hydroxybenzonic acid, were used to investigate the regulatory effects on allelopathy of a wild rice accession of S37 （Oryza Iongistaminata）, which is a known allelopathic rice. The four exogenous phenolic acids induced the enhancement of the allelopathic potential of wild rice S37 in target weeds though the weed-suppressive activities were low, and the inducible effects were dependent on the specific phenolic acid, concentration and treatment time. After foliar application of exogenous phenolic acids, the inhibition rates for plant height, root length and fresh weight of barnyard grass （Echinochioa crus-galli） were significantly higher than those of the control. Especially at the concentration of 100 mg/L, the inhibition rates for plant height and fresh weight of barnyard grass by fumalic acid were 38.12% and 26.31% higher than those of the control, showing that fumalic acid was more effective compared with other phenolic acids in inhibiting monocotyledon weed growth. Furthermore, the weedsuppressive activity of aqueous extract from the leaves of wild rice S37 treated with exogenous phenolic acids was increased, and it peaked at 48 h after the treatment with the aqueous extract, and then gradually declined.

The effects of phenolic acid on nitrogen metabolism in Populus 3 euramericana ‘Neva’

The declines in soil fertility and productivity in continuously cropped poplar plantations axe related to phenolic acid accumulation in the soil. Nitrogen is a vital life element for poplar and whether the accumulation of phenolic acid could influence nitrogen metabolism in poplar and thereby hinder continuous cropping is not clear. In this study, poplar cuttings of Populus × euramericana ‘Neva＇ were potted in vermiculite, and phenolic acids at three concentrations （032, 0.5X and 1.0X） were added according to the actual content （1.0X） in the soil of a second-generation poplar plantation. Each treatment had eight replicates. We measured gas exchange parameters and the activities of key enzymes related to nitrogen metabolism in the leaves. Leaf photosynthetic parameters varied with the concentration of phenolic acids. The net photosynthetic rate （PN） significantly decreased with increasing phenolic acid concentration, and non-stomatal factors might have been the primary limitation for PN- The activities of nitrate reductase （NR）, glutamine synthetase （GS） and glutamate synthase （GOGAT）, as well as the contents of nitrate nitrogen, ammonium nitrogen, and total nitrogen in the leaves decreased with increasing phenolic acid concentration. This was significantly and positively related to PN （P 〈 0.05）. The low concentration of phe- nolic acids mainly affected the transformation process of NO3- to NO2-, while the high concentration of phenolic acids affected both processes, where NO3- was transferred to NO2- and NH4＋ was transferred to glutamine （Gln）. Overall, phenolic acid had significant inhibitory effects on the photosynthetic productivity of Populus x euramericana ＇Neva＇. This was probably due to its influence on the activities of nitrogen assimilation enzymes, which reduced the amount of amino acids that were translated into protein and enzymes. Improving the absorption and utilization of nitrogen by plants could help to overcome the problems caused by continuous cropping.

Effects of Phenolic Acids on Growth and Activities of Membrane Protective Enzymes of Cucumber Seedlings

Two phenolic acids P-hydroxy benzoic acid and cinnamic acid were designated as four concentrations (0, 50 μmol/L, 100 μmol/L, 150 μmol/L) to investigate the effects of phenoic acids on the growth and the activities of membrane protective enzymes of cucumber seedlings. The results showed that both phenolic acids inhibited the seedlings growth. The inhibitory effects were increased with the concentration of phenolic acids increasing and the time of treatment prolonging. Seedlings treated with A150 (P-hydroxy benzoic acid, 150 μmol/L), B50 (cinnamic acid, 50 μmol/L), B100 (cinnamic acid, 100 μmol/L), B150 (cinnamic acid, 150 μmol/L) showed significantly shorter in plant height , smaller in leaf area. and lighter in fresh weight. The inhibitory effect of cinnamic acid was comparatively stronger than that of P-hydroxy benzoic acid. For protective enzymes system, compared to control , the POD activity increased at all concentrations of P-hydroxy benzoic acid during the treatment but increased at first then decreased before increased again at last at all concentrations of cinnamic acid .In the case of CAT, its activity increased at first, then decreased, and increased again at lower concentrations of phenolic acids. However, at higher concentrations the activities decreased at first, then increased a little, decreased continuously at last. In addition, the treatments of phenolic acids led to an increase then a decreaseof SOD activity and an increase of MDA content in the seedlings. All above indicated the accumulating of free radicalsand destruction of protective enzymes at higher concentrations of phenolic acids.

PRZEWALSKINIC ACID A,A NEW PHENOLIC ACID FROM SALVIA PRZEWALSKII MAXIM

From the root of Salvia przewalskii Maxim.a new phenolic acid, przewalskinic acid A was isolated and the structure was established by the analysis of^(13)C-NMR,~1H-NMR and two-dimensional COSY experiments.

Study on Optimization of Ethanol Reflux Extraction of Phenolic Acids from Salvia miltiorrhiza

The extraction technology of phenolic acid compounds from Salvia miltiorrhiza by ethanol reflux was studied. In this experiment, salvianolic acid B standard was used to make the standard curve. Single factor experiment and orthogonal experiment were used to study the extraction of different ethanol concentrations, reflux times and material-to-liquid ratios. The OD value of salvianolic acid compounds was measured with a spectrophotometer. The extraction rate of phenolic acid compounds under different extraction conditions was calculated through a regression equation, so as to obtain the optimal conditions for the ethanol reflux extraction process of Salvia miltiorrhiza. The experimental data can provide a reference for the ethanol reflux extraction process of salvianolic acids in the industry. According to the experiment, the extraction rate of phenolic acids in Salvia miltiorrhiza was the highest when the ethanol concentration was 60%, the reflux time was 1.5 hours, and the ratio of material-to-liquid was 1:10.

Application of HPLC and ESI-MS techniques in the analysis of phenolic acids and flavonoids from green leafy vegetables (GLVs)

Diets containing high proportions of fruits and vegetables reduce the risk of onset of chronic diseases. The role of herbal medicines in improving human health is gaining popularity over the years, which also increases the need for safety and efficiency of these products. Green leafy vegetables （GLVs） are the richest source of phenolic compounds with excellent antioxidant properties. Increased consumption of diets containing phenolic compounds may give positive and better results to human health and significantly improves the immune system. Highly selective, susceptible and versatile analytical techniques are necessary for extraction, identifica- tion, and quantification of phenolic compounds from plant extracts, which helps to utilize their important biological properties. Recent advances in the pre-treatment procedures, separation techniques and spectro- metry methods are used for qualitative and quantitative analysis of phenolic compounds. The online coupling of liquid chromatography with mass spectrometry （LC-MS） has become a useful tool in the metabolic profiling of plant samples. In this review, the separation and identification of phenolic acids and flavonoids from GLVs by LC-MS have been discussed along with the general extraction procedures and other sources of mass spectrometer used. The review is devoted to the understanding of the structural configuration, nature and accumulation pattern of phenolic acids and flavonoids in plants and to highlighting the recent developments in the chemical investigation of these compounds by chromatographic and spectroscopic techniques. It concludes with the advantages of the combination of these two methods and prospects.

Temperature and Acidified Solvent Effect on Total Anthocyanins and RP-HPLC Phenolic Acids Determination in Selected Spices

Total anthocyanins of spices (Syzygium aromaticum L., Coriadrum sativum L., Cuminum cyminum L., Zingiber officinale Rosc., Elettaria cardamomum, Curcuma longa, Rhus coriaria L., Cinnamomum zeylanicum Blume, Foeniculum vulgare Mill and Laurus nobilis L.) were determined using acidified (1% HCl) solvents (methanol, ethanol and acetone) at three temperatures (20℃, 40℃ and 60℃). Also phenolic acids were separated and identified by RP-HPLC. Results showed that sumac and cinnamon had the highest levels of anthocyanins, while for the acetone the cinnamon indicated the highest amount of anthocyanins when methanol and ethanol were used as extracting solvents at 20℃. At 40℃ using ethanol, sumac showed the highest level of anthocyanins whereas acetone solvent yielded the highest anthocyanin contents for cinnamon. At 60℃, cinnamon showed the highest level of anthocyanins when methanol and acetone were the solvents, while sumac had the highest anthocyanins level using ethanol as solvent. HPLC results showed ten phenolic acids found in those spices and varied in their concentrations. Gallic acid had the highest level (1642.3 mg/100g) (cloves). Gentisic acid had the lowest level (1.2 mg/100g) in ginger. Also sumac showed the highest level of chlorogenic acid (1528.7 mg/100g). Some acids were not found in some spices, for instance, benzoic acid was not found in coriander, cumin, ginger, green cardamom, cinnamon and sweet laurel.

Research Progress on Application Effect of Biomass Charcoal and Its Restoration of Soil Phenolic Acid Pollution

Biomass charcoal has positive effects on reducing soil nutrient loss, increasing fertilizer utilization, reducing organic pollution and pesti-cide residues, inhibiting pollutant enrichment, and reducing bioavailability of pollutants. In this paper, the concept and effect of biomass charcoal were reviewed; the research situation of phenolic pollutants in soil was described; and the research progress on restoration of soil phenolic acid pol-lution by biomass charcoal application was summarized.

Effects of Exogenous Phenolic Acids on Allelopathy of Potted Soybean Seedlings

In this study, several general y reported exogenous phenolic acids were selected as regents for potting experiments, aiming at revealing the effects of differ-ent concentrations of exogenous phenolic acids on the growth and development of soybean seedlings. The growth and development indicators of soybean seedlings treated with five different concentrations of exogenous phenolic acids, such as plant height, leaf area, root nodule number and root-shoot ratio, were determined and compared. According to the experimental results, three exogenous phenolic acids with different concentrations exhibited slight effects on plant height of potted soy-bean seedlings. The leaf area of potted soybean seedlings treated with 1.0 g/kg benzoic acid and cinnamic acid varied extremely significantly compared with the control. Root nodule number of potted soybean seedlings treated with 1.0 g/kg ben-zoic acid and vanil ic acid increased remarkably, but 1.0 g/kg cinnamic acid had lit-tle effects on root nodule number. When the concentration of phenolic acids was 1.0 g/kg, three phenolic acids exhibited the maximum effects on root-shoot ratio of potted soybean seedlings. Overal , low concentrations of exogenous phenolic acids exhibited no significant effects on the growth and development of potted soybean seedlings; high concentrations of exogenous phenolic acids inhibited the growth and development of potted soybean shoots, increased root nodule number and improved root-shoot ratio.

Phenolic Acids Content and Nutritional Quality of Conventional, Organic and Biodynamic Cultivations of the Tomato CXD271BIO Breeding Line (Solanum lycopersicum L.)

This study was undertaken to evaluate the influence of growing systems (conventional, organic and biodynamic performed with two types of manuring) on some nutritional traits of the tomato breeding line CXD271BIO (Solanum lycopersicum L.). Experimental fields were in the same geographical area and the cultivations were performed over five years. The content of macronutrients, minerals (Ca, K, Mg, P, Na), trace elements (Fe, Zn, Cu, Mn) and phenolic acids (chlorogenic, caffeic, p-coumaric and ferulic acids) was determined. The biodynamic A growing system showed the highest protein and carbohydrates content compared to the other growing systems. Data on minerals and trace elements content showed significant differences (mainly in Ca, Na, Fe and Zn content) between conventional and biodynamic tomatoes, whereas no major impact of the fertilization among organic and the two biodynamic growing systems was observed. Appreciable differences in phenolic acids biosynthesis were observed, with the year of harvest showing a marked effect especially on chlorogenic, p-cumaric and ferulic acids content. Conversely, the cultivation system did not show major influence. Principal Components Analysis (PCA), performed on mineral and phenolic acids content, substantiated the large effect of the year of harvest, also suggesting an effect of the conventional cultivation system.

The Blocking Effect of Phenolic Acid on N-Nitrosomorpholine Formation in vitro

Phenolic acids (PAs) are widely found in many daily consumed vegetables and fruits.The inhibitory effects of PAs on Nnitrosomorpholine (NMOR) formation in vitro undersimulated gastric juice condition were studied. The results showed that the inhibjtoryIX)tency of thirteen varieties of PAs differed greatly, which may be related to theirchemical structures; the blocking rate (BR) of different killds of PAs were as follows:caf feic acid, 92.5%; tannic acid, 90.0%; gallic acid, 86.8%; sinaPinic acid, 86.2%; ferulicacid, 8l.l%; chlorogenic acid, 69.4%; gentisic acid, 69.2%; syringic acid, 62.1%; protocatechuic acid, 56.0%; p-coumaric acid, 52.5%; vannilic acid, 35.4%; moreover,p-hydroxybenzoic acid and m-coumaric acid had the least blocking effect or even slightcatalyzing effect. The results also demonstrated that amounts of NMOR formed werenegatively correlated with molar ratio of PAs to nitrite and that the optimum pH forinhibition was between 2 and 3.

Review on Comparative Analyses of Different Phenolic Acids Content in Different Beers

Beer can be a rich source of phenolic acids in the diet. The present review summarizes the current state of work on phenolic acids in beer presented in the cited papers. In an overview, 10 hydroxybenzoic acids, three related aldehydes, two phenylacetic acids and eight hydroxycinnamic acids in beer are being reported. This review compares the phenolic acids content in alcoholic and non-alcoholic beers from Czech Republic, Germany, Italy, Austria and Poland, which had been examined by several authors. The quantification was achieved by HPLC with ultraviolet, diode array, coulometric array or fluorimetric detection. Ferulic acid is the main phenolic acid in all beers that had been studied, followed by p-coumaric, vanillic, caffeic, p-OH-benzoic and sinapic acids. Most of the phenolic acids in beer are present as bound forms and only a small portion can be detected as free compounds. The content of the phenolic acids in the non-alcoholic beers is lower than in the alcoholic beers mainly due to differences in the production process, yeast strains used, dealcoholization of beer etc..

Addition Mechanisms of Phenol toward Formaldehyde under Acidic Condition: a Theoretical Investigation

The reaction mechanisms of phenol with formaldehyde in the first and second addition at the ortho- and para-position in acid solution were theoretically investigated at the PW91/DNP level with solvent effects included. The reaction of phenol with protonated methanediol firstly forms an adduct intermediate, via a SN2 mechanism with a water molecule as the leaving group. From the adduct intermediate, there are two reaction channels involving a proton transfer to form the addition products. One is that a proton directly transfers via a four-membered ring transition state with a notable energy barrier （Four-member mechanism）. Another mechanism involving a water molecule as catalyst to mediate the proton transfer （WCP mechanism）, is a barrierless process, indicating that the formation of the adduct intermediate, the first reaction step, is rate-limiting. The reaction products are free hydroxymethyl phenols and/or hydroxybenzy carbocation （HOC6H4CH2＋） which plays an important role in the following formation of methylene and methylene ether linkages. The second addition reactions between formaldehyde and hydroxymethyl phenol at all possible reaction sites of the phenol ring in acid solution were also investigated and discussed.

Comparison between Sulfuric Acid-phenol and Sulfuric Acid-anthrone Methods Used for Determination of Polysaccharides in Shoots of Aralia elata (Miq.) Seem.

Sulfuric acid-phenol and sulfuric acid-anthrone methods were used to detect polysaccharide content in shoots of Aralia elata（ Miq.） Seem.,and the conversion factor to glucose was measured with refined polysaccharides. Comprehensive evaluation was carried out by linear relationship,precision,reproducibility,stability and recovery rate. The results showed that the linear relationship between glucose concentration and absorbance was good when glucose concentration was0-40 μg/ml,and the average recovery rate was equal to or higher than 97. 00% with good reproducibility（ RSD 〈 1. 60%,n = 5）. It revealed that the two methods were accurate and reliable,and suitable for the determination of polysaccharide content in the shoots of A. elata. Polysaccharide content detected by sulfuric acid-phenol and sulfuric acid-anthrone methods was 19. 31% and 20. 40% respectively.

Analysis of the Fatty Acids and Phenolic Compounds in a Cereal-Based Fermented Food (Tarhana)

Tarhana is a Turkish home-made fermented food product. The mixture of wheat flour, yoghurt, yeast, cooked vegetables, salt, and spices is fermented for 1 - 7 days. Tarhana is sun dried and ground for preparation of instant Tarhana powder. Color, phenolic compounds and fatty acid composition were determined for home-made Tarhana, collected from 4 cities in the Thrace Region of Turkey. Color and phenolic content were significantly different (P < 0.05). These differences were due to the variation of ingredients used at different locations. The major unsaturated fatty acids were oleic (C18:1, 16.41% - 57.69%), and linoleic acids (C18:2, 9.74% - 56.31%). Palmitic (C16:0, 16.90% - 37.66%) and stearic acids (C18:0, 0.65% - 11.34%) were the main saturated fatty acids. This study suggested that Tarhana soup is a good source of unsaturated fatty acids. Antioxidant properties of phenolic compounds and their effect on peroxidation of lipids in Tarhana should be tested in future studies.

Phenolic Acid Content and Free Radical-Scavenging Activity of Two Differently Processed Carob Tree(Ceratonia siliqua L.)Pod

The phenolic acids in free phenolic acid (FPHA), methanol-soluble phenolic ester (MSPE), and methanol-soluble phenolic glycoside (MSPG) fractions of two carob products, natural carob-pod flour (CPF) and commercial carob-pod flour (CCPF), were identified and quantified using high-performance liquid chromatography-mass spectrometry (HPLC-MS). Six phenolic acids were identified in the carob flours (gallic acid, protocatechuic acid, gentisic acid, syringic acid, p- coumaric acid, and sinapic acid). Gallic acid was the major phenolic acid;and its concentrations in CCPF were substantially higher than in CPF (135 - 166 and 85.2 - 91.3 mg/g dw, respectively). The concentrations of p-coumaric acid and sinapic acid were also higher in CCPF than in CPF. In contrast, the concentrations of protocatechuic acid and gentisic acid were generally lower in CCPF than in CPF, with the only exception being gentisic acid glycosides. Both carob-pod flours contained almost the same amount of sinapic acid and syringic acid. The total phenolic contents of the FPHA, MSPE, and MSPG fractions of CPF were found to be 44%, 38%, and 69% that of the respective fractions of CCPF. Correspondingly, the FPHA, MSPE, and MSPG fractions of CCPF had higher free radical-scavenging activity (28.4%, 33.1%, and 26.2%, respectively) than the corresponding fractions of CPF (9.2%, 28.0%, and 9.2%, respectively). Notably, the FPHA and MSPG fractions of each sample had very similar scavenging activity while the MSPE fraction always had higher activity. The FPHA and MSPG fractions of CPF had the lowest activities.