Silicon, endophytes and secondary metabolites as grass defenses against mammalian herbivores

Article Accepted Date: 30 August 2014 Acknowledgments This study was supported by the Academy of Finland (grant no. 133495 to Otso Huitu; grants no. 137909 and 110658 to Kari Saikkonen) and by the NERC (grant no. NE/F003994/1 to Xavier Lambin). We thank Dr. Stefan Reidinger and Dr. James Stockdale for help with the silicon analyses. Technician Sinikka Sorsa conducted the phenolic extractions. Stephen Ryan and Anaïs Zimmer assisted with field work.Peer reviewedPublisher PD

Metabolic engineering of Escherichia coli into a versatile glycosylation platform : production of bio‐active quercetin glycosides

Background: Flavonoids are bio-active specialized plant metabolites which mainly occur as different glycosides. Due to the increasing market demand, various biotechnological approaches have been developed which use Escherichia coli as a microbial catalyst for the stereospecific glycosylation of flavonoids. Despite these efforts, most processes still display low production rates and titers, which render them unsuitable for large-scale applications. Results: In this contribution, we expanded a previously developed in vivo glucosylation platform in E. coli W, into an efficient system for selective galactosylation and rhamnosylation. The rational of the novel metabolic engineering strategy constitutes of the introduction of an alternative sucrose metabolism in the form of a sucrose phosphorylase, which cleaves sucrose into fructose and glucose 1-phosphate as precursor for UDP-glucose. To preserve these intermediates for glycosylation purposes, metabolization reactions were knocked-out. Due to the pivotal role of UDP-glucose, overexpression of the interconverting enzymes galE and MUM4 ensured the formation of both UDP-galactose and UDP-rhamnose, respectively. By additionally supplying exogenously fed quercetin and overexpressing a flavonol galactosyltransferase (F3GT) or a rhamnosyltransferase (RhaGT), 0.94 g/L hyperoside (quercetin 3-O-galactoside) and 1.12 g/L quercitrin (quercetin 3-O-rhamnoside) could be produced, respectively. In addition, both strains showed activity towards other promising dietary flavonols like kaempferol, fisetin, morin and myricetin. Conclusions: Two E. coli W mutants were engineered that could effectively produce the bio-active flavonol glycosides hyperoside and quercitrin starting from the cheap substrates sucrose and quercetin. This novel fermentation-based glycosylation strategy will allow the economically viable production of various glycosides

Euphorbia-derived natural products with potential for use in health maintenance

Euphorbia genus (Euphorbiaceae family), which is the third largest genus of angiosperm plants comprising ca. 2000 recognized species, is used all over the world in traditional medicine, especially in the traditional Chinese medicine. Members of this taxa are promptly recognizable by their specialized inflorescences and latex. In this review, an overview of Euphorbia-derived natural products such as essential oils, extracts, and pure compounds, active in a broad range of biological activities, and with potential usages in health maintenance, is described. The chemical composition of essential oils from Euphorbia species revealed the presence of more than 80 phytochemicals, mainly oxygenated sesquiterpenes and sesquiterpenes hydrocarbons, while Euphorbia extracts contain secondary metabolites such as sesquiterpenes, diterpenes, sterols, flavonoids, and other polyphenols. The extracts and secondary metabolites from Euphorbia plants may act as active principles of medicines for the treatment of many human ailments, mainly inflammation, cancer, and microbial infections. Besides, Euphorbia-derived products have great potential as a source of bioactive extracts and pure compounds, which can be used to promote longevity with more health.Agência financiadora FCT/MCT, supporting the cE3c centre UID/BIA/00329/2013 UID/BIA/00329/2019 QOPNA research Unit (FCT) UID/QUI/00062/2019info:eu-repo/semantics/publishedVersio

Characterization of Plum Procyanidins by Thiolytic Depolymerization

The phenolic compounds of ?Green Gage? (GG) plums (Prunus domestica L.), ?Rainha Cla?udia Verde?, from a ?protected designation of origin? (PDO), in Portugal, were quantified in both flesh and skin tissues of plums collected in two different orchards (GG-V and GG-C). Analyzes of phenolic compounds were also performed on another GG European plum obtained in France (GG-F) and two other French plums, ?Mirabelle? (M) and ?Golden Japan? (GJ). Thiolysis was used for the first time in the analysis of plum phenolic compounds. This methodology showed that the flesh and skin contain a large proportion of flavan-3-ols, which account, respectively, for 92 and 85% in GJ, 61 and 44% in GG-V, 62 and 48% in GG-C, 54 and 27% in M, and 45 and 37% in GG-F. Terminal units of procyanidins observed in plums are mainly (+)-catechin (54?77% of all terminal units in flesh and 57?81% in skin). The GJ plums showed a phenolic composition different from all of the others, with a lower content of chlorogenic acid isomers and the presence of A-type procyanidins as dimers and terminal residues of polymerized forms. The average degree of polymerization (DPn) of plum procyanidins was higher in the flesh (5?9 units) than in the skin (4?6 units). Procyanidin B7 was observed in the flesh of all GG plums and in the skin of the Portuguese ones. Principal component analysis of the phenolic composition of the flesh and skin of these plums obtained after thiolysis allowed their distinction according to the variety and origin, opening the possibility of the use of phenolic composition for variety/origin identification

Extraction of phenolic compounds from organic dried apples: comparison between conventional, microwave- and ultrasound-assisted extraction methods

The aim of this study was to compare a conventional assay with microwave- (MAE) and ultrasound- (UAE) assisted extraction methods on the extraction of phenolic compounds from organic dried apples by evaluating the content in catechin, epicatechin, chlorogenic acid and quercitrin. Samples from two apple varieties (Golden Rush and Topaz) were analyzed. Methanol/water (70:30, v/v) was selected as the solvent mixture for the phenolic compounds extractions. The High Performance Liquid Chromatography coupled to diode array detection (HPLC-DAD) were used for the identification and quantification of the respective phenolic compounds. Qualitative analysis revealed similar phenolic profiles in both apple varieties. Whatever extraction method is used, in both apple varieties chlorogenic acid and epicatechin were present in higher contents compared to catechin and quercitrin with chlorogenic acid being the major contributor. It was found a better extraction of chlorogenic acid, catechin and quercitrin (only for Topaz apple) using conventional process in comparison with MAE and UAE. A higher content of quercitrin was obtained with MAE and UAE compared to conventional method. The content of phenolic compounds in Golden Rush apple was higher than in Topaz apple. Results from this study indicated that conventional extraction can be a more efficient process than MAE and UAE for the extraction of phenolic compounds from organic dried apples

Soluble and insoluble-bound phenolics and antioxidant activity of various industrial plant wastes

The potential of selected industrial food wastes from juice and nut production including apple peel, apple pomace, pomegranate peel, pomegranate seed, chestnut shell, and black carrot pomace as resources for natural antioxidants was investigated. Soluble free and insoluble-bound phenolics were extracted from the wastes and analyzed for total phenolic and flavonoid contents, phenolic profile and antioxidant activity. Total phenolic and total flavonoid contents of wastes were positively correlated with their antioxidant activity. The highest total phenolic and antioxidant activity were determined in soluble fraction of pomegranate peel due to a significant amount of punicalagin derivatives. Pomegranate peel and seed had the most phenolics and flavonoids in soluble form while other wastes had more than 45% of total phenolics in insoluble-bound form. Chestnut shell showed more antioxidant activity in insoluble-bound fraction compared to that of its soluble fraction. These findings showed that not only soluble but also an insoluble-bound fraction of the industrial wastes has good potential for valorization as a source of natural antioxidants

Application of reverse-flow micellar electrokinetic chromatography for the simultaneous determination of flavonols and terpene trilactones in Ginkgo biloba dosage forms

A reverse-flow micellar electrokinetic chromatographic (RF-MEKC) method was developed for the simultaneous qualitative determination of 10 components consisting of the flavonol glycosides, rutin and quercitrin, the flavonol aglycones, isorhamnetin, kaempferol and quercetin, the terpene trilactones, ginkgolides A, B, C and J and the sesquiterpene, bilobalide. This method was used to fingerprint Ginkgo biloba solid oral dosage forms and validated for the quantitation of the marker compounds, rutin and quercetin in some commercial products. In addition to the usual variables, the influence of some essential background electrolyte (BGE) components such as sodium dodecyl sulphate (SDS) and -cyclodextrin concentrations were investigated. A polyimide fused-silica square capillary column (75 μm I.D. × 360 μm O.D.) with a total length of 60.0 cm and effective length of 45.0 cm was used for the separation. The final BGE consisted of 20 mM phosphoric acid, 40 mM SDS and 12 mM -cyclodextrin (pH 2.2) using reverse polarity with a voltage of −17.5 kV. Samples were injected electrokinetically at −5 kV for 3 s for the qualitative analysis and hydrodynamically at 20 mbar for 0.6 s for the quantitative assay. The total run time was 22 min and the limits of detection were 3.13 μg/ml and 1.88 μg/ml for rutin and quercetin, respectively. Fingerprint profiles of the solid oral dosage forms and the results of the quantitative analysis indicated that there were major discrepancies in the marker content between products and illustrates the value of this method for use as a procedure to assess product quality of commercially available Ginkgo biloba products

Safety assessment and antioxidant activity of Lantana montevidensis leaves

Lantana camara, the widely studied species, and L. montevidensis, the less studied species of the genus Lantana are both used in traditional medicine for the same purpose (anti-asthma, anti-ulcer, anti-tumor, etc). However, little is known about the toxicity of L. montevidensis and there is limited information on its chemical constituents. Here, we investigated for the first time the genotoxicity and cytotoxicity of the ethanolic (EtOH) and aqueous extracts from the leaves of Lantana montevidensis in human leukocytes, as well as their ossible interaction with human erythrocyte membranes in vitro. The antioxidant activities of both extracts were also investigated in chemical and biological models. Treatment of leukocytes with EtOH or aqueous extracts (1-480 µg/mL) did not affect DNA damage index, but promoted cytotoxicity at higher concentrations (240-480 µg/mL). Both extracts did not modify the osmotic fragility of human erythrocytes. The extracts scavenged DPPH radical and prevented Fe2+-induced lipid peroxidation in rat’s brain and liver homogenates, and this was likely not attributed to Fe (II) chelation. The HPLC analysis of the extracts showed different amounts of polyphenolic compounds (isoquercitrin, gallic acid, catechin, ellagic acid, apigenin, kaempferol, caffeic acid, rutin, quercitrin, quercetin, chlorogenic acid, luteolin) that may have contributed to these effects. These results supported information on the functional use of L. mon-tevidensis in folk medicine

Phytochemical Investigation and B Ioactivity Screening of Vitex (Verbenaceae) and Ficus (Moraceae) Species

The study on Vitex longisepala involves extraction, various chromatographic methods and structural determination by spectroscopic techniques such as IR, compounds were also elucidated by comparison with the previous works. works on leaves and bark of the plant yielded cholesterol (51),para-hydroxybenzoic acid (52), terpene. Crude extracts and isolated compounds from two parts of this plant were screened for antimicrobial activity using disc diffusion method and cytotoxic activity by using microtitration method. compouds exhibited antimicrobial activity against Gram-possitive and Gram-negative bacteria Cholesterol exhibited significant cytotoxic activity against T-lymphoblastic leukemic cell line with IC₅₀ 10 µg/ml. not show any antimicrobial activity against fungi. The methanol crude extract of the bark failed to show any significant antimicrobial activity, while the petroleum ether and the chloroform crude extracts of the bark exhibited weak antimicrobial activity against Bacillus cereus. The study on Vitex quinata involved the same procedure adopted above. Isolation works on the leaves and bark of the plant yielded cholesterol (51), 13- sitosterol (57), para-hydroxybenzoic acid (52), fructose (53), glucose (58), catechin (55), quercetin (59) and quercitrin (60). However, the bark of the plant yielded a mixture of long-chain compound, fatty acid and unidentified terpene. The crude extracts and isolated compounds of this plant were tested for antimicrobial and cytotoxic activity using disc diffusion and microtitration methods respectively. The crude extracts and pure isolated compounds exhibited positive antimicrobial results against two bacteria organisms and negative results against four fungi. Cholesterol and β-sitosterol gave cytotoxic activity against T -lymphoblastic leukemic cell line with IC₅₀ 10 and 25 µg/ml respectively. Detail investigation on the leaves, bark and fruits of Ficus benjamina has resulted in the isolation of seven compounds. The structure of these compounds were elucidated by means of spectroscopic methods including by the extensive use of various NMR techniques and also comparison with previous studies. The use of High Field NMR is essential in structural determination of these complex molecules. With the aids of various NMR experimental techniques and oth er spectroscopic methods such as IR, UV and MS, the correct structures of the pure isolated compounds were established. (63), The presence of bioactive compounds in th is plant was detected by the use of antimicrobial organism. crude plant extracts or pure isolated compounds could be determined. of chloroform and methanol extracts of the leaves of Ficus benjamina gave no significant activity while caffeic acid gave IC₅₀ value of 25 µg/ml. Phytochemical studies on leaves and bark of Ficus elastica have resulted in the isolation of emodin (66), (70) together with long-chain fatty acids. were established based on spectral studies using different spectroscopic methods and on comparison with published data

Silicon-induced changes in antifungal phenolic acids, flavonoids, and key phenylpropanoid pathway genes during the interaction between miniature roses and the biotrophic pathogen <em>Podosphaera pannosa</em>

Application of 3.6 mm silicon (Si+) to the rose (Rosa hybrida) cultivar Smart increased the concentration of antimicrobial phenolic acids and flavonoids in response to infection by rose powdery mildew (Podosphaera pannosa). Simultaneously, the expression of genes coding for key enzymes in the phenylpropanoid pathway (phenylalanine ammonia lyase, cinnamyl alcohol dehydrogenase, and chalcone synthase) was up-regulated. The increase in phenolic compounds correlated with a 46% reduction in disease severity compared with inoculated leaves without Si application (Si−). Furthermore, Si application without pathogen inoculation induced gene expression and primed the accumulation of several phenolics compared with the uninoculated Si− control. Chlorogenic acid was the phenolic acid detected in the highest concentration, with an increase of more than 80% in Si+ inoculated compared with Si− uninoculated plants. Among the quantified flavonoids, rutin and quercitrin were detected in the highest concentrations, and the rutin concentration increased more than 20-fold in Si+ inoculated compared with Si− uninoculated plants. Both rutin and chlorogenic acid had antimicrobial effects on P. pannosa, evidenced by reduced conidial germination and appressorium formation of the pathogen, both after spray application and infiltration into leaves. The application of rutin and chlorogenic acid reduced powdery mildew severity by 40% to 50%, and observation of an effect after leaf infiltration indicated that these two phenolics can be transported to the epidermal surface. In conclusion, we provide evidence that Si plays an active role in disease reduction in rose by inducing the production of antifungal phenolic metabolites as a response to powdery mildew infection