不同来源丹参药材酚酸类成分的分析研究

为比较不同来源的丹参(Salvia miltiorrhiza)药材的酚酸类成分,采用化学指纹图谱和定量分析的方法,对不同来源丹参药材中的酚酸类成分进行了系统分析。结果表明:产地、采收期、病害、根色、根的粗细以及药材部位等因素尽管对丹参酚酸类成分绝对含量的影响比较大,但对各成分相对含量的影响较小;不同来源丹参药材酚酸类成分指纹图谱相似性较高;8月份采收的药材,丹酚酸B含量较高;病害能够显著降低丹酚酸B的积累;与白根和褐色根相比,砖红色根中的丹酚酸B含量较高;根越粗,丹酚酸B含量也越高。这为丹参药材的品质评价和资源利用提供了依据。     

Significance of phenols in cadmium and nickel uptake

The effects of 2-aminoindane-2-phosphonic acid (AIP), a potent phenylalanine ammonia-lyase (PAL) inhibitor, on the accumulation of cadmium and nickel in chamomile (Matricaria chamomilla) were examined in this study. In vitro assay of AIP effect showed a 90% reduction in PAL activity. In plants cultured for 7 days in Cd or Ni solutions with AIP, PAL activity was higher in both shoots and roots (in comparison with metals without AIP), and was correlated with changes in free phenylalanine content. Individual amino acids were both positively and negatively affected by AIP, with the accumulation of tyrosine and proline showing increases in some variants. Contents of soluble phenols and flavonoids were not considerably affected, while amounts of coumarin-related compounds, cell wall-bound phenols and phenolic acids were substantially reduced in AIP-treated variants. Lignin accumulation decreased in controls and increased in Cd variants in response to AIP. Shoot Cd content was depleted, but shoot Ni was elevated by AIP. Total root content of Cd and Ni decreased in +AIP variants. AIP also caused more expressive changes in hydrogen peroxide and superoxide content in Cd than in Ni variants. Our results indicate that phenols have important roles in the uptake of Cd and Ni. The present findings are discussed in the context of available data regarding AIP's effect on phenols.     

An allelopathic investigation of the domination of the introduced invasive Conyza canadensis L.

The introduced, invasive species Conyza canadensis L. covers large areas of the sandy levees next to the River Tamiš (Serbia), forming dense microcomplexes and dominating the other herbaceous species in the ruderal phytocoenosis with its aboveground mass and abundance. In addition to this species, a further 28 plant species were found, but the abundance and cover of these was significantly lower. The allelopathic influence of the species C. canadensis was investigated through analyzing the total phenolics and phenolic acids, as the main allelochemicals, in dead and vegetative parts and the soil beneath them. Seed germination and seedling growth of the target plants (Dactylis glomerata L. and Trifolium repens L.), which grow in this community, served as a measure of the inhibitory capacity of this species. It was established that the content of total phenolics and phenolic acids (p-coumaric, ferulic, p-hydroxybenzoic, vanillic and syringic) varies, following the order: vegetative plant parts > dead plant parts > sandy soil under C. canadensis. Water leachate and soils inhibited seed germination and seedling growth of the test plants to varying degrees, following the order: vegetative parts > dead parts > sandy soil, which is directly related to the content of total phenolics and phenolic acids in them. It was concluded that the pioneer species C. canadensis plays a decisive role in the first phases of vegetation succession and the process of soil formation on the barren sandy levees, owing to the synthesis of secondary phenolic metabolites.     

Phenol and phenolics from lignocellulosic biomass by catalytic microwave pyrolysis

Catalytic microwave pyrolysis of biomass using activated carbon was investigated to determine the effects of pyrolytic conditions on the yields of phenol and phenolics. The high concentrations of phenol (38.9%) and phenolics (66.9%) were obtained at the temperature of 589 K, catalyst-to-biomass ratio of 3:1 and retention time of 8 min. The increase of phenol and its derivatives compared to pyrolysis without catalysts has a close relationship with the decomposition of lignin under the performance of activated carbon. The concentration of esters was also increased using activated carbon as a catalyst. The high content of phenols obtained in this study can be used either directly as fuel after upgrading or as feedstock of bio-based phenols for chemical industry.     

Exogenously applied glycinebetaine enhances seed and seed oil quality of maize (Zea mays L.) under water deficit conditions

A field trial was carried out to appraise up to what extent exogenous application of a potential osmoprotectant, glycinebetaine (GB), could ameliorate the inhibitory effects of shortage of water on maize seed and seed oil composition and oil antioxidant potential. Two maize cultivars, Agaiti-2002 (drought tolerant) and EV-1098 (drought sensitive), were exposed to drought treatments at the vegetative growth stage. Both the maize cultivars used in the present study are being widely cultivated in Pakistan and have been an important source of developing different maize hybrids. Two levels of glycinebetaine (0 or 30 mM) were foliar-applied at the vegetative stage. Water stress reduced the kernel sugar, oil, protein, moisture contents and most of the seed micro- and macro-nutrients analyzed of both maize cultivars, but it increased the contents of seed fiber and ash contents. Among different seed oil un-saturated fatty acids, water stress increased the oil oleic acid contents with a decrease in linoleic acid contents, which resulted in increased oil oleic/linoleic ratio of both maize cultivars. However, no variation was observed in oil stearic and palmitic acid contents due to water stress. A considerable increase in seed oil α-, γ-, δ- and total tocopherols and flavonoids was observed in both maize cultivars. However, oil phenolic content and 1,1′-diphenyl-2-picryl-hydrazyl (DPPH) free radical scavenging activity decreased. Foliar-applied GB significantly increased the contents of seed sugar, oil, protein, moisture, fiber, ash, GB contents and micro- and macro-nutrients of both maize cultivars under well irrigated and water deficit conditions. Furthermore, exogenous application of GB increased the oil oleic and linoleinic acid contents. All different lipophilic compounds estimated in the seed oil increased due to foliar applied GB. Furthermore, GB also increased seed oil antioxidant activity appraised in terms of oil DPPH free radical scavenging activity. By summarizing the results, it seemed that exogenously applied GB remained in intact form until later stages of growth and counteracted the inhibitory effects of water deficit on seed and seed oil composition similarly of both maize cultivars.     

Metabolic diversion of the phenylpropanoid pathway causes cell wall and morphological changes in transgenic tobacco stems

Studies involving transgenic plants with modifications in the lignin pathway reported to date, have received a relatively preliminary characterisation in relation to the impact on vascular integrity, biomechanical properties of tissues and carbon allocation to phenolic pools. Therefore, in this study transgenic tobacco plants (Nicotiana tabacum cv XHFD 8) expressing various levels of a bacterial 4-hydroxycinnamoyl-CoA hydratase/lyase (HCHL) gene have been characterised for cell wall and related morphological changes. The HCHL enzyme converts p-coumaroyl-CoA to 4-hydroxybenzaldehyde thereby rerouting the phenylpropanoid pathway. Plants expressing high levels of HCHL activity exhibited reduced lignin deposition, impaired monolignol biosynthesis and vascular integrity. The plants also exhibited reduction in stem toughness concomitant with a massive reduction in both the cell wall esterified and soluble phenolics. A notable result of redirecting the carbon flux was the wall-bound accretion of vanillin and vanillic acid, probably due to the shunt pathway. Intracellular accumulation of novel metabolites such as hydroxybenzoic and vanillic acid derivatives also occurred in the transgenic plants. A line with intermediate levels of HCHL expression conferred correspondingly reduced lignin deposition, toughness and phenolics. This line displayed a normal morphology but distorted vasculature. Coloration of the xylem has been previously attributed to incorporation of alternative phenolics, whereas results from this study indicate that the coloration is likely to be due to the association of low molecular weight phenolics. There was no evidence of increased growth or enhanced cellulose biosynthesis as a result of HCHL expression. Hence, rerouting the phenylpropanoid biosynthetic pathway quantitatively and qualitatively modifies cell wall-bound phenolics and vascular structure.     

Phenolics during early development of <Emphasis Type="Italic">Betula pubescens</Emphasis> seedlings: inhibition of phenylalanine ammonia lyase

We studied phenolic metabolism and plant growth in birch seedlings at the beginning of their development by inhibiting phenylalanine ammonia lyase (PAL), which is the first committed step in phenylpropanoid metabolism. Betula pubescens (Ehrh.) seeds were germinated in inhibitor-free media and the seedlings were transferred to hydroponic culture at the cotyledon stage. They were 6 days old at the start of the experiment, which lasted for 3 weeks. PAL activity was inhibited by three different concentrations of 2-aminoindane-2-phosphonic acid monohydrate (AIP) in the growing media. At the end of 3 weeks, phenolics in all plant parts (roots, stem, cotyledons, first, second and third true leaves) were determined. AIP inhibited strongly the accumulation of phenolic acids, salidroside, rhododendrins, ellagitannins and their precursors, flavan-3-ols, and soluble condensed tannins. The accumulation of lignin and flavonol glycoside derivatives was moderately inhibited. The accumulation of flavonol glycosides, such as quercetin glycosides and kaempferol glycosides, was not generally inhibited, even in leaves that emerged during the experiment, while the accumulation of insoluble condensed tannins was inhibited only slightly and not in all plant parts. This suggests that flavonol glycosides, which may have a UV-B protective role, and insoluble condensed tannins, which may have structural functions, are prioritized in seedling development. Inhibition of PAL with AIP decreased seedling growth and possible reasons for this are discussed. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Genetic background impacts soluble and cell wall-bound aromatics in <Emphasis Type="Italic">brown midrib</Emphasis> mutants of sorghum

Sorghum (Sorghum bicolor (L.). Moench) BMR-6 and BMR-12 encode cinnamylalcohol dehydrogenase and caffeic acid-O-methyltransferase, respectively. We have evaluated the impact of two bmr alleles, bmr-6 and bmr-12, respectively, on soluble and wall-bound aromatics in near isogenic, wild-type (WT), bmr-6, bmr-12 and double-mutant (DM; bmr-6 and bmr-12) plants in two genetic backgrounds, RTx430 and Wheatland. Immunoblots confirmed that COMT protein was essentially absent in bmr-12 and DM plants, but was present in bmr-6 and WT plants. In contrast, although CAD activity was not detected in bmr-6 and DM plants, proteins crossreacting to anti-CAD sera were found in stem extracts from all genotypes. In both sorghum backgrounds, WT plants had lowest amounts of free aromatics, higher levels of cell wall-bound pCA and FA esters and guaiacyl (G), syringyl (S), and p-hydroxyphenyl (H) lignins. Soluble aromatics and cell wall phenolic ester content in Wheatland DM plants resembled that of Wheatland bmr-6 plants, whereas in the RTx430 background, levels of these components in the DM plants more closely resembled those observed in bmr-12 plants. In both backgrounds, bmr-6 plants exhibited reduced levels of G, S, and H lignins relative to WT, and increased incorporation of G-indene into lignin. In bmr-12 plants, there was greater incorporation of G- and 5-hydroxyguaiacyl (5-OHG) lignin into cell walls. Histochemical staining of internode sections from Wheatland plants indicated that apparent lignification of cortical sclerenchyma and vascular bundle fibers was greatest and most uniform in WT plants. Relative staining intensity of these tissues was decreased in bmr-6, followed by bmr-12 plants. DM plants exhibited poor staining of cortical sclerenchyma and vascular bundle fibers. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture.     

Age-dependent shift in response to food element composition in Collembola: contrasting effects of dietary nitrogen

Developing leaves that are soft, with high concentrations of resources, can be particularly vulnerable to herbivore damage. Since a developing leaf cannot be very tough, given the constraints of cell expansion, the major form of protection is likely to be chemical defence. We investigated changes in concentration of herbivore resources (protein, carbohydrates and water) and putative defences (total phenolics, tannin activity, cyanogenic glycosides, alkaloids, cell wall, and leaf mechanics) across five leaf development stages of the soft-leaved Toona ciliata M. Roem. and the tough-leaved Nothofagus moorei (F. Muell.) Krasser. Chemical defences were predicted to be more highly developed in young than expanded leaves of both species, and to decline more in expanded leaves of N. moorei, which become tough and strong at maturity, than in the softer expanded leaves of T. ciliata. Resources and defences were dynamic within the developing leaves. Highest concentrations of protein were recorded in young leaves in both species, and highest levels of non-structural carbohydrate were recorded in young leaves of T. ciliata. Allocation to defence varied in both amount and type across leaf stages. In T. ciliata, there was an increase in chemical defence in expanded leaves (tannin activity, alkaloids). However, in N. moorei, increasing strength and toughness of developing leaves coincided with decreasing chemical defence, consistent with our hypothesis. For phenolics, this decrease was partly due to dilution by cell wall, but cyanogenic glycosides were present in young leaves and absent in fully mature leaves. These results are consistent with leaf toughness acting as an effective anti-herbivore defence, thereby reducing the need for investment in chemical defence.