Antioxidant activities of natural phenolic compounds from Acacia confusa bark

The present study showed that the ethanolic extracts from the bark of Acacia confusa exhibited a strong antioxidant activity. Among all the fractions from ethanolic extracts of bark, the EtOAc soluble fraction exhibited the best antioxidant performance. Furthermore, following by CC and HPLC, 11 pure phenolic compounds were isolated and identified from the ethanolic extracts.     

The conversion of L-phenylalanine into benzoic acid on the thylakoid membrane of higher plants.

The conversion of L-phenylalanine into benzoic acid and other aromatic carboxylic acids was investigated in Nasturtium officinale (watercress), Astilbe chinensis, and Hydrangea macrophylla in vivo and in vitro. Comparative feeding experiments with radioactively labelled L-phenylalanine and cinnamic acid administered to intact leaf discs of A. chinensis indicated a rapid formation of benzoic acid from L-phenylalanine, whereas cinnamic acid was a poor precursor. Using a pulse-chase labelling technique followed by a fractionation of the tissue into subcellular components, chloroplasts could be identified as the predominant, if not exclusive, site of benzoic acid formation in A. chinensis. Experiments in vitro with chloroplasts and thylalkoids of N. officinale, H. macrophylla, and A. chinensis demonstrate the capacity of thylakoid membranes to catalyze the degradation of L-phenylalanine to benzoic acid. The results obtained upon stimultaneous incubation with [4'-3H]L-phenylalanine and [3-14C]cinnamic acid lead to the hypothesis that the reaction of L-phenylalanine to benzoic acid proceeds via a cinnamic acid pool which is different from that of soluble cinnamic acid.     

Isolation and characterization of thermophilic bacilli degrading cinnamic, 4-coumaric,and ferulic acids

Thirty-four thermophilic Bacillus sp. strains were isolated from decayed wood bark and a hot spring water sample based on their ability to degrade vanillic acid under thermophilic conditions. It was found that these bacteria were able to degrade a wide range of aromatic acids such as cinnamic, 4-coumaric, 3-phenylpropionic, 3-(p-hydroxyphenyl)propionic, ferulic, benzoic, and 4-hydroxybenzoic acids. The metabolic pathways for the degradation of these aromatic acids at 60 degrees C were examined by using one of the isolates, strain B1. Benzoic and 4-hydroxybenzoic acids were detected as breakdown products from cinnamic and 4-coumaric acids, respectively. The beta-oxidative mechanism was proposed to be responsible for these conversions. The degradation of benzoic and 4-hydroxybenzoic acids was determined to proceed through catechol and gentisic acid, respectively, for their ring fission. It is likely that a non-beta-oxidative mechanism is the case in the ferulic acid catabolism, which involved 4-hydroxy-3-methoxyphenyl-beta-hydroxypropionic acid, vanillin, and vanillic acid as the intermediates. Other strains examined, which are V0, D1, E1, G2, ZI3, and H4, were found to have the same pathways as those of strain B1, except that strains V0, D1, and H4 had the ability to transform 3-hydroxybenzoic acid to gentisic acid, which strain B1 could not do.     

Isolation and Characterization of Thermophilic Bacilli Degrading Cinnamic, 4-Coumaric, and Ferulic Acids

Thirty-four thermophilic Bacillus sp. strains were isolated from decayed wood bark and a hot spring water sample based on their ability to degrade vanillic acid under thermophilic conditions. It was found that these bacteria were able to degrade a wide range of aromatic acids such as cinnamic, 4-coumaric, 3-phenylpropionic, 3-(p-hydroxyphenyl)propionic, ferulic, benzoic, and 4-hydroxybenzoic acids. The metabolic pathways for the degradation of these aromatic acids at 60°C were examined by using one of the isolates, strain B1. Benzoic and 4-hydroxybenzoic acids were detected as breakdown products from cinnamic and 4-coumaric acids, respectively. The β-oxidative mechanism was proposed to be responsible for these conversions. The degradation of benzoic and 4-hydroxybenzoic acids was determined to proceed through catechol and gentisic acid, respectively, for their ring fission. It is likely that a non-β-oxidative mechanism is the case in the ferulic acid catabolism, which involved 4-hydroxy-3-methoxyphenyl-β-hydroxypropionic acid, vanillin, and vanillic acid as the intermediates. Other strains examined, which are V0, D1, E1, G2, ZI3, and H4, were found to have the same pathways as those of strain B1, except that strains V0, D1, and H4 had the ability to transform 3-hydroxybenzoic acid to gentisic acid, which strain B1 could not do.     

微小杆菌(Exiguobacterium sp.)对肉桂酸降解行为

【目的】为有效缓解自毒物质肉桂酸对西瓜等作物生长的危害,从宁夏中卫硒砂瓜连作土壤中分离筛选得到一株高效降解肉桂酸的菌株,研究其基本降解特性。【方法】分离筛选得到一株能有效利用肉桂酸生长的菌株,采用16S r RNA基因序列分析进行菌株鉴定,运用高效液相色谱法和西瓜幼苗生长毒性实验检测降解特性。【结果】从多年西瓜连作土壤中筛选得到一株高效降解肉桂酸的细菌R30,鉴定为Exiguobacterium sp.,其96 h内对肉桂酸的降解率可达99%以上,最适降解温度和p H分别为30°C、p H 7.0。除肉桂酸外,该菌也能够高效降解香豆酸、阿魏酸、苯甲酸等其他酚酸类物质,表现出一定的底物广谱性;检测96 h降解液对西瓜种子萌发直至幼苗生长阶段的影响表明,该菌株可有效缓解肉桂酸对西瓜幼苗的生长抑制作用。【结论】菌株R30在肉桂酸、香豆酸、阿魏酸、苯甲酸等酚酸类物质导致的农作物连作障碍治理领域具有潜在的开发应用价值。     

Phenols removal in musts: Strategy for wine stabilization by laccase

The potential of laccase from Trametes versicolor for phenolic removal in must for wine stabilization was evaluated through a combination of an analytical methodology (capillary zone electrophoresis) and kinetics of phenols removal as the total antioxidant potential variation. Total phenolic content, total antioxidant potential and polyphenols were monitored from 0 to 3 h of must treatment. The results indicated that the treatment of a red must with laccase affect mainly the phenolic compounds responsible for the must antioxidant properties. The treatment of white musts with laccase showed higher reduction in total phenol than in the total antioxidant potential. Phenol degradation by laccase was very fast for catechins, and slowly for stilbenes (cis- and trans-resveratrol) and derivatives of cinnamic (ferulic and caffeic) and benzoic (syringic, vanillic, and gallic) acids. It is possible to conclude in this case that the use of laccase in white wines is perfectly feasible. This would allow softer and ecologically correct treatments, which would diminish the cost of processing and avoid deterioration of wines for long storage times.     

New insights into the antioxidant activity of hydroxycinnamic and hydroxybenzoic systems: Spectroscopic,electrochemistry, and cellular studies

Abstract

A series hydroxycinnamic and gallic acids and their derivatives were studied with the aim of evaluating their in vitro antioxidant properties both in homogeneous and in cellular systems. It was concluded from the oxygen radical absorbance capacity-fluorescein (ORAC-FL), 1,1-diphenyl-2-picrylhydrazyl (DPPH), and cyclic voltammetry data that some compounds exhibit remarkable antioxidant properties. In general, in homogeneous media (DPPH assay), galloyl-based cinnamic and benzoic systems (compounds 7–11) were the most active, exhibiting the lowest oxidation potentials in both dimethyl sulfoxide (DMSO) and phosphate buffer. Yet, p-coumaric acid and its derivatives (compounds 1–3) disclosed the highest scavenging activity toward peroxyl radicals (ORAC-FL assay). Interesting structure–property– activity relationships between ORAC-FL, or DPPH radical, and redox potentials have been attained, showing that the latter parameter can be a valuable antioxidant measure. It was evidenced that redox potentials are related to the structural features of cinnamic and benzoic systems and that their activities are also dependent on the radical generated in the assay. Electron spin resonance data of the phenoxyl radicals generated both in DMSO and phosphate buffer support the assumption that radical stability is related to the type of phenolic system. Galloyl-based cinnamic and benzoic ester-type systems (compounds 9 and 11) were the most active and effective compounds in cell-based assays (51.13 ± 1.27% and 54.90 ± 3.65%, respectively). In cellular systems, hydroxycinnamic and hydroxybenzoic systems operate based on their intrinsic antioxidant outline and lipophilic properties, so the balance between these two properties is considered of the utmost importance to ensure their performance in the prevention or minimization of the effects due to free radical overproduction.     

非洲白参的抗氧化活性及其化学成分研究

采用DPPH（1,1-二苯基-2-三硝基苯肼）、ABTS（2,2-联氮-双-3-乙基苯并噻唑-6-磺酸）自由基清除法和FRAP（铁离子还原/抗氧化能力）法对非洲白参（Mondia whiteii（Hook.f.）Skeels）不同萃取部位的抗氧化活性进行分析,然后采用紫外分光光度法和福林酚比色法分别测定非洲白参不同萃取部位的总黄酮、总酚含量,最后采用大孔树脂AB-8、ODS以及Sephadex LH-20柱层析和半制备型HPLC等色谱分离技术对其二氯甲烷萃取部位的化学成分进行分离、纯化。结果显示：非洲白参二氯甲烷萃取部位抗氧化活性最高,且二氯甲烷萃取部位的总酚含量远高于其他部位;化学成分分离、纯化后得到10个单体化合物,分别为：2-羟基-4-甲氧基苯甲醛（1）、秦皮素（2）、7-甲氧基香豆素（3）、α-羟基丁香丙酮（4）、ω-hydroxypropioguaiacone（5）、桂皮酸（6）、水杨酸（7）、4-甲氧基水杨酸（8）、丁香酸（9）、壬二酸（10）。其中,化合物3~10为首次从该植物中分离得到。     

Bioactivity-based analysis and chemical characterization of hypoglycemic and antioxidant components from Artemisia argyi

Diabetes is one of the metabolic disorders in the world. It is the prime reason of mortality and morbidity owing to hyperglycemia which is link with numerus obstacles. Artemisia argyi is commonly used as an ingredient in healthy foods as well as an herbal medicine in Asian countries. The present research aims to evaluate the hypoglycemic effects of A. argyi and reveal its the potentially active constituents. The chemical composition was identified by HPLC-DAD-Q-TOF-MS, and fractionation was performed by extraction. The fractions were assessed by the blood glucose level, oral glucose tolerance and small intestinal α-glucosidase inhibitory tests, and an analysis of the total phenolic content (TPC), antioxidant and α-glucosidase inhibitory activities. In our efforts to characterize the compounds responsible for hypoglycemic effect, bioactivity-guided fraction of the MeOH extract and chemical investigation of its active EtOAc fraction led to the successful identification of caffeoylquinic acids, which were elucidated by molecular docking, using the crystal structure of S. cerevisiae isomaltase (PD code: 3AXI). In summary, this bio-guided search revealed that caffeoylquinic acids from A. argyi as potential active constituents displayed with hypoglycemic activity, which provided a basis for further study of pharmacological activity.     

Cinnamic esters of acyclovir-synthesis and biological activity

In the present study we have synthesized esters of acyclovir with cinnamic acids (p-coumaric, ferulic, and sinapic acids) and evaluated them for their antiviral and antioxidant potential. The antiviral activity of the newly synthesized compounds has been tested against human herpes virus 1 (HSV-1) in vitro. The results indicate that none of the synthesized compounds inhibits the tested virus strain. The antioxidant properties have been studied using 2,2-diphenyl-1-picrylhydrazyl (DPPH)* test.     

Antioxidant activities of ethanolic extracts from the twigs of Cinnamomum osmophloeum

Cinnamomum osmophloeum Kaneh. is an indigenous tree species in Taiwan. In this study, phytochemical characteristics and antioxidant activities of ethanolic extracts from the twigs of C. osmophloeum were investigated for the first time. The extracts were obtained successively using liquid-liquid partition to yield n-hexane (Hex), ethyl acetate (EtOAc), n-butanol (BuOH) and water fractions. The antioxidant activities of C. osmophloeum twig extracts were examined using various antioxidant assays, such as DPPH, NBT, reducing power, lipid peroxidation using mouse brain homogenates, metal chelating ability, and photochemiluminescence (PCL). In addition, total phenolic contents were also determined. Results revealed that the BuOH fraction exhibited the best performance in DPPH assay, NBT assay, reducing power assay and lipid peroxidation using mouse brain homogenates assay. Furthermore, the BuOH fraction has the highest total phenolic contents (496.7 mg of GAE/g). Consequently, kaempferol-7-O-rhamnoside was also isolated from the antioxidative BuOH fraction and its activity was also confirmed. These results demonstrated that ethanolic extracts of C. osmophloeum twigs have excellent antioxidant activities and thus it has great potential as a source for natural health products.     

Antibacterial activity directed isolation of compounds from Onosma hispidum

The chemical investigation of the ethanolic extract of the root bark of Onosma hispidum following antibacterial activity directed isolation led to the isolation of 4-hydroxy-3-methoxy cinnamic acid (ferulic acid) and 4-hydroxy-3-methoxy benzoic acid (vanillic acid) which have been reported for the first time in this species. In addition to these compounds, the crude ethanolic extract and methanol fraction exhibited substantial bioactivity against species of corynebacteria, enterococci, staphylococci and streptococci. Ferulic acid was found more bioactive (being relatively more hydrophobic) compared to vanillic acid.     

基于ORAC评价多酚类化合物抗氧化活性

采用氧自由基清除能力(ORAC)方法考察20种多酚类化合物的抗氧化活性。结果表明,该方法具有较优的线性关系(R2=0.997）;检测限(LOD）和定量限(LOQ）为0.5～3.1 μmol·L-1,精密度＜18%,准确度91%～105%。比较20种多酚类化合物抗氧化活性,对羟基苯甲酸类化合物中,鞣花酸和没食子酸具有较强的抗氧化活性;对羟基肉桂酸类以咖啡酸及其衍生物抗氧化活性最高;在类黄酮组分中,黄烷-3-醇表现出优良的抗氧化特性,黄酮醇次之。ORAC可作为评价多酚类化合物抗氧化的简便、高效的标准化检测方法。     

Biologically active constituents of a polyphenol extract from Geranium sanguineum L. with anti-influenza activity

From the aerial roots of the medicinal plant Geranium sanguineum L. a polyphenol-rich extract with strong anti-influenza activity has been isolated. To investigate its active fractions, the extract was partitioned by solvents with increasing polarity. The n-BuOH fraction contained the majority of the in vitro antiviral activity; the EtOAc fraction was the most effective one in vivo. A bioassay-directed fractionation of the n-BuOH and EtOAc fractions was performed to obtain information about the nature of the chemical components of the plant extract, responsible for the antiviral effect. The individual constituents were identified by spectroscopic methods and comparison with authentic samples and by HPLC. The cell-toxic and virus-inhibitory effects of the fractions and some individual polyphenol compounds, found in Geranium sanguineum L., were studied using the replication of representative influenza viruses in cell cultures. This study showed that the presence of a variety of biologically active compounds as well as the possible synergistic interactions between them seem to be decisive for the overall antiviral effect.     

Chemistry and pharmacology of oxyprenylated secondary plant metabolites

Oxyprenylated natural products (isopentenyloxy-, geranyloxy- and the less spread farnesyloxy- compounds and their biosynthetic derivatives) represent a family of secondary metabolites that have been considered for years just as biosynthetic intermediates of C-prenylated derivatives. Only in the last decade these natural products have been recognized as interesting and valuable biologically active phytochemicals. Up to now about 300 molecules have been isolated from plants mainly belonging to the families of Rutaceae and Compositae, comprising common edible vegetables and fruits. A wide variety of compounds containing a prenyloxy side chain have been isolated and these comprise alkaloids, coumarins, flavonoids, cinnamic acids, benzoic acids, phenols, alcohols, aldehydes, anthraquinones, chalcones, lignans, xanthones, aceto- and benzophenones and other more uncommon skeletons. Many of the isolated oxyprenylated natural products and their semisynthetic derivatives were shown to exert in vitro and in vivo remarkable anti-cancer, anti-inflammatory, anti-microbial and anti-fungal effects. The aim of this review is to examine in detail the different types of oxyprenylated natural compounds from a phytochemical and pharmacological point of view.     

In vitro antioxidant activity of polyphenol extracts with antiviral properties from Geranium sanguineum L

Recent evidence shows that plant polyphenols exhibit antioxidant and radical scavenging properties. By three separate and complementary methods--DPPH assay, beta-carotene-linoleic acid assay and NBT-reduction assay it was established that a polyphenol-rich extract from the medicinal plant Geranium sanguineum L. with strong anti-influenza virus activity, possessed antioxidant and radical scavenging capacities. For comparative reasons caffeic acid and the synthetic antioxidant BHT were used. Total soluble phenolic constituents of the MeOH extract measured by Folin-Ciocalteu reagent were found as 34.60% (w/w). Further it was demonstrated that the EtOAc fraction, retaining the majority of the in vivo protective effect exhibited a strong O2-scavenging activity while the n-BuOH fraction, containing the majority of the in vitro antiviral activity provoked generation of O2-. The O2- scavenging activity of all three preparations correlated with the rate of the protective effect shown in the murine model of experimental influenza virus infection. The present results are in accordance with our intensive studies on the mode of the protective effect of the plant extract which showed positively that the protection may possibly be attributed to the combination of more than one biological activities and that the use of antioxidants might be an useful approach in the treatment of influenza infection.     

Phenylpropanoid Metabolism in Suspension Cultures of Vanilla planifolia Andr. : III. Conversion of 4-Methoxycinnamic Acids into 4-Hydroxybenzoic Acids

Feeding of 4-methoxycinnamic acid, 3,4-dimethoxycinnamic acid and 3,4,5-trimethoxycinnamic acid to cell suspension cultures of Vanilla planifolia resulted in the formation of 4-hydroxybenzoic acid, vanillic acid, and syringic acid, respectively. The homologous 4-methoxybenzoic acids were demethylated to the same products. It is concluded that the side chain degrading enzyme system accepts the 4-methoxylated substrates while the demethylation occurs at the benzoic acid level. The demethylating enzyme is specific for the 4-position. Feeding of [O-¹⁴C-methyl]-3,4-dimethoxycinnamic acid revealed that the first step in the conversion is the glycosylation of the cinnamic acid to its glucose ester. A partial purification of a UDP-glucose: trans-cinnamic acid glucosyltransferase is reported. 4-Methoxy substituted cinnamic acids are better substrates for this enzyme than 4-hydroxy substituted cinnamic acid. It is suggested that 4-methoxy substituted cinnamic acids are intermediates in the biosynthetic conversion of cinnamic acids to benzoic acids in cells of V. planifolia.     

皱环球盖菇不同极性萃取物抗氧化活性比较及成分分析

为考察皱环球盖菇子实体的抗氧化活性,利用溶剂萃取法得到皱环球盖菇子实体二氯甲烷、乙酸乙酯、正丁醇和水4种不同极性萃取物,选用二苯基三硝基苯肼自由基(DPPH)法、羟基自由基法和还原力法对4种萃取物进行体外抗氧化活性分析。结果表明,乙酸乙酯萃取物显示了最强的抗氧化活性;通过超高效液相色谱串联三重四级杆飞行时间质谱法(UPLC-Triple-TOF/MS)分析了皱环球盖菇乙酸乙酯萃取物中化学组成,从中鉴定出9种化合物,多数为核苷类物质,具有很好的抗氧化活性。研究结果为皱环球盖菇的开发提供了理论依据和技术支持。