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PubMed2003

Researching on new species of "Mate": Ilex brevicuspis: phytochemical and pharmacology study.

BACKGROUND: Ilex paraguariensis St. Hilaire (Aquifoliaceae) ("Mate" or "Yerba mate") is one of the most commercialized plants of South America which grows naturally in NE Argentina, Uruguay, SE Brazil and E Paraguay, where it is also cultivated. It is used to prepare a tea-like beverage (infusions or decoctions) appreciated for its peculiar flavor, stimulation and nutritional properties. Ilex brevicuspis Reisseck grows in the same habitat and is widely used as a substitute or adulterant of Ilex paraguariensis. In a previous work, methylxanthines (caffeine, theobromine and theophylline) were not detected in it by HPLC. AIM OF THE STUDY: This study was undertaken in order to isolate, identify and quantify the polyphenolic compounds (caffeoyl derivatives and flavonoids) and to investigate some of the pharmacological activities of I. brevicuspis, related with the traditional use of the "Mate" (choleretic, intestinal propulsion and antioxidant activities). Acute toxicity was also investigated. METHODS: Decoctions, like extracts, were prepared in order to compare the results with preparations commonly used by the local people. For the phytochemical analysis, the extracts were analyzed by HPLC with a diode array detector. Choleretic and intestinal propulsion activities were assayed in rats. Sodium dehydrocholate (DHC) was used as a choleretic reference standard. Antioxidant activity was tested in liposomes that were oxidized by the free radical generator 2,2'-azobis [amidinopropane] chloride (AAPH). RESULTS: For the first time in I. brevicuspis the following compounds were isolated and quantified: A) caffeoyl derivative compounds (chlorogenic acid; caffeic acid; 3,4-dicaffeoylquinic acid; 3,5-dicaffeoylquinic acid and 4,5-dicaffeoylquinic acid. B) flavonoids (rutin, quercetin and kaempferol). Biological activity assays demonstrated that I. brevicuspis extracts produced a significant increase of bile flow (BF) in rats in the first 30 min period and in the percentage of BF increase accumulated at 120 min. It also produced an increase in the intestinal propulsion activity. Moreover, this species showed a high antioxidant activity. The acute toxicity test showed that Ilex brevicuspis did not produce any sign of toxicity at the analyzed doses. CONCLUSIONS: An Argentinean Ilex specie ( I. brevicuspis) has choleretic, intestinal propulsion, antioxidant activities and these results may lead to the potential development of a new "Yerba Mate" and/or phytopharmaceutical products, without central nervous system (CNS) stimulant activity.

Animals↗
PubMed1996

Ascorbate is the natural substrate for plant peroxidases.

Ascorbate-dependent detoxification of hydrogen peroxide by guaiacol-type peroxidases is increased considerably in the presence of 3,4-dihydroxyphenolic compounds, suggesting that ascorbate is the natural substrate for many types of peroxidase in situ and not just the ascorbate-specific peroxidases. The ascorbate-dependent destruction of hydrogen peroxide in the more acidic cellular compartments such as the vacuole may be an important function of such non-specific peroxidases. The stress-induced production of phenolic compounds would render the guaiacol peroxidases in other less acidic-cellular sites effective as ascorbate-dependent H2O2-detoxifying enzymes.

Antibodies↗
PubMed1992

Green tea composition, consumption, and polyphenol chemistry.

Tea is grown in about 30 countries but is consumed worldwide, although at greatly varying levels. It is the most widely consumed beverage aside from water with a per capita worldwide consumption of approximately 0.12 liter per year. Tea is manufactured in three basic forms. Green tea is prepared in such a way as to preclude the oxidation of green leaf polyphenols. During black tea production oxidation is promoted so that most of these substances are oxidized. Oolong tea is a partially oxidized product. Of the approximately 2.5 million metric tons of dried tea manufactured, only 20% is green tea and less than 2% is oolong tea. Green tea is consumed primarily in China, Japan, and a few countries in North Africa and the Middle East. Fresh tea leaf is unusually rich in the flavanol group of polyphenols known as catechins which may constitute up to 30% of the dry leaf weight. Other polyphenols include flavanols and their glycosides, and depsides such as chlorogenic acid, coumarylquinic acid, and one unique to tea, theogallin (3-galloylquinic acid). Caffeine is present at an average level of 3% along with very small amounts of the other common methylxanthines, theobromine and theophylline. The amino acid theanine (5-N-ethylglutamine) is also unique to tea. Tea accumulates aluminum and manganese. In addition to the normal complement of plant cell enzymes, tea leaf contains an active polyphenol oxidase which catalyzes the aerobic oxidation of the catechins when the leaf cell structure is disrupted during black tea manufacture. The various quinones produced by the enzymatic oxidations undergo condensation reactions which result in a series of compounds, including bisflavanols, theaflavins, epitheaflavic acids, and thearubigens, which impart the characteristic taste and color properties of black tea. Most of these compounds readily form complexes with caffeine. There is no tannic acid in tea. Thearubigens constitute the largest mass of the extractable matter in black tea but their composition is not well known. Proanthocyanidins make up part of the complex. Tea peroxidase may be involved in their generation. The catechin quinones also initiate the formation of many of the hundreds of volatile compounds found in the black tea aroma fraction. Green tea composition is very similar to that of the fresh leaf except for a few enzymatically catalyzed changes which occur extremely rapidly following plucking. New volatile substances are produced during the drying stage. Oolong tea is intermediate in composition between green and black teas.

Agriculture↗
PubMed2004

The modifying effect of Peucedanum japonicum, a herb in the Ryukyu Islands, on azoxymethane-induced colon preneoplastic lesions in male F344 rats.

The modifying effect of dietary Peucedanum japonicum (PJ), which is a traditional herb in the Ryukyu Islands and is an anti-oxidant, on azoxymethane (AOM)-induced rat colon carcinogenesis was examined. Male F344 rats were divided into six groups: rats in groups 1-4 were given subcutaneous injection of AOM (20 mg/kg body weight) once a week for 2 weeks. Rats in groups 2, 3 and 4 were fed the diets containing 0.2 and 1% PJ and 0.025% chlorogenic acid, respectively. We observed modification of the preneoplastic lesions of both aberrant crypt foci (ACF) and beta-catenin accumulated crypts (BCAC) in colon carcinogenesis, microscopically and immunohistochemically. The numbers of ACF consisting of more than four aberrant crypts per rat in groups 2 (3.2+/-1.7) and 3 (3.0+/-3.2) were significantly lower than that of group 1 (10.8+/-4.9; P<0.05, respectively). The mean number of BCAC in both groups 2 (0.88+/-0.48/cm2/rat) and 3 (0.81+/-0.34/cm2/rat) was significantly lower than that in group 1 (2.13+/-0.54/cm2/rat; P < 0.0001, respectively). In addition, proliferating cell nuclear antigen labeling indices in group 2 (10.98+/-2.03) and group 3 (9.85+/-2.62) were significantly lower than that in group 1 (14.87+/-3.93; P < 0.001 and P < 0.0001, respectively). These findings indicate that PJ inhibits both ACF formation and accumulation of beta-catenin, and that PJ also reduces the cell proliferation activity, suggesting that PJ may have chemopreventive potential for colon carcinogenesis.

Animals↗
PubMed2004

Analysis of biologically active compounds in potatoes (Solanum tuberosum), tomatoes (Lycopersicon esculentum), and jimson weed (Datura stramonium) seeds.

Potatoes and tomatoes, members of the Solanaceae plant family, serve as major, inexpensive low-fat food sources providing for energy, high-quality protein, fiber, vitamins, pigments, as well as other nutrients. These crops also produce biologically active secondary metabolites, which may have both adverse and beneficial effects in the diet. This limited overview, based largely on our studies with the aid of HPLC, TLC, ELISA, GC-MS, and UV spectroscopy, covers analytical aspects of two major potato trisaccharide glycoalkaloids, alpha-chaconine and alpha-solanine, and their hydrolysis products (metabolites) with two, one, and zero carbohydrate groups; the potato water-soluble nortropane alkaloids calystegine A3 and B2; the principal potato polyphenolic compound chlorogenic acid; potato inhibitors of digestive enzymes; the tomato tetrasaccharide glycoalkaloids dehydrotomatine and alpha-tomatine and hydrolysis products; the tomato pigments beta-carotene, lycopene, and chlorophyll; and the anticholinergic alkaloids atropine and scopolamine present in Datura stramonium (jimson weed) seeds that contaminate grain and animal feed. Related studies by other investigators are also mentioned. Accurate analytical methods for these food ingredients help assure the consumer of eating a good-quality and safe diet.

Chromatography, High Pressure Liquid↗
PubMed2005

Comparison between sample disruption methods and solid-liquid extraction (SLE) to extract phenolic compounds from Ficus carica leaves.

Sea sand disruption method (SSDM) and matrix solid phase disruption (MSPD) were compared to solid-liquid extraction (SLE) for extraction of phenolic compounds from the Ficus carica leaves. Statistical treatment, ANOVA-single factor, was used to compare the extraction yields obtained by these methods, and for the majority of the extracted compounds, significantly higher yields were obtained by the solid disruption methods. Both solid disruption methods are faster and ecologically friendly, but the sea sand method was more reproducible (RSD < 5% for most compounds), and was also the least expensive method. Recoveries above 85% were obtained for chlorogenic acid, rutin, and psoralen using the sea sand extraction method.

Chemical Fractionation↗
PubMed2006

Development and evaluation of methods for determination of naphthodianthrones and flavonoids in St. John's wort.

Several major constituents in St. John's wort were determined for a homogenized plant sample. Three extraction techniques were evaluated: Soxhlet extraction, pressurized-fluid extraction (PFE), and sonication extraction. Levels of nine constituents (chlorogenic acid, rutin, hyperoside, isoquercitrin, quercitrin, quercetin, amentoflavone, pseudohypericin, and hypericin) were measured using liquid chromatography with ultraviolet/visible absorbance, mass spectrometric, and fluorescence detection. Levels of total naphthodianthrones determined by liquid chromatography (LC) with absorbance detection at 590 nm were compared with levels determined by direct spectrophotometry at the same wavelength. Additionally, the methods described in this paper were applied to several brands of St. John's wort finished products.

Anthracenes↗
PubMed2005

Elimination of bitter, disgusting tastes of drugs and foods by cyclodextrins.

The bitter taste of drugs, food components, and any other substances which get in the mouth as dissolved in an aqueous solution, or in the saliva, can be strongly reduced or fully eliminated, if the bitter component forms an inclusion complex with an appropriate cyclodextrin (CD). The value of the complex association constant (determined by the structure of the bitter 'guest' molecule and the size and eventual substitution of the 'host' CD molecule), the temperature and the host/guest ratio determine the extent of complexation of the guest molecule (percentage of complexation) at the equilibrium. The K(ass) for most drug/CD complexes at 36 degrees C buccal cavity temperature is between 10(2) and 10(4) mol-1. If the unit dose (of a sublingual or chewing tablet, chewing gum) with a bitter drug (molecular weight of about 150, forming a 1:1 complex with betaCD) is approximately 10mg then the betaCD can be taken in a 5- or even 10-fold molar excess. Under such conditions more than 99% of the bitter drug is complexed, and because complexed molecules cannot react with the taste buds in the buccal cavity no bitter taste is perceived. Frequently, preparation of the drug/CD complex is not necessary, because the betaCD is present in a large excess, dissolved very quickly in the saliva and results in a saturated CD solution. Therefore, the complexation of the bitter drug is completed very rapidly. Only dissolved substances have taste and only CD complexable drug molecules can become debittered by CDs. Bitter, astringent components of foods (e.g. soya), beverages (e.g. naringin in citrus fruit juice, or chlorogenic acid and polyphenols in coffee) cigarette smoke (nicotine) also can be complexed and their taste reduced or fully eliminated.

Cyclodextrins↗
PubMed2005

Effects of blue honeysuckle (Lonicera caerulea L.) extract on lipopolysaccharide-induced inflammation in vitro and in vivo.

The aim of the present study was to investigate the effects of blue honeysuckle extract (BHE), which contains high level of phenolic compounds, on endotoxin-induced uveitis (EIU). Male Lewis rats were randomly divided into 5 groups with 14 rats in each (eight rats for collection of aqueous humor, six rats for histologic examination). EIU was induced by a footpad injection of lipopolysaccharide (LPS). 1, 10, or 100 mg of BHE was injected intravenously immediately after LPS injection. The aqueous humor was collected at 24 h after LPS injection, the number of infiltrating cells, protein concentration, nitric oxide (NO), tumor necrosis factor (TNF)-alpha, and prostaglandin (PG)-E2 levels in the aqueous humor were determined. Some eyes were enucleated for histologic examination and immunohistochemical analysis. Immunohistochemical staining with a monoclonal antibody against activated nuclear factor (NF)-kappaB was performed to evaluate the effect of BHE on NF-kappaB activation. To further clarify the anti-inflammatory effect, RAW264.7 cells (a mouse macrophage cell line) were stimulated with LPS in the presence or absence of BHE and its major phenolics, cyanidin 3-glucoside (C3G), cyanidin 3-rutinoside (C3R), chlorogenic acid (CA). Expression of inducible NO synthase (iNOS) and cyclooxygenase-2 (COX-2) were analyzed by Western blot method. BHE treatment significantly reduced the inflammatory cell infiltration, the protein concentration, the levels of NO, TNF-alpha and PGE2 in the aqueous humor and improved histologic status of the ocular tissue. The number of activated NF-kappaB-positive cells was lower in the iris-ciliary body treated with BHE at 3 h after LPS injection. BHE significantly suppressed the production of NO, PGE2 and TNF-alpha in the culture medium as well as the expression of iNOS and COX-2 by LPS-stimulated RAW264.7 cells in a dose-dependent fashion. C3G, C3R and CA showed no or weak inhibitory effects on the level of inflammatory mediators and the expression of iNOS and COX-2. These results suggest that BHE attenuates the degree of inflammation in eyes with EIU by inhibiting the NF-kappaB dependent signaling pathway and the subsequent production of proinflammatory mediators.

Animals↗
PubMed2004

Antioxidant compounds from Chaerophyllum hirsutum extracts.

Antioxidant activity of sequential extracts obtained from Chaerophyllum hirsutum was tested using the reaction with the stable radical 1,1 diphenyl-2-picrylhydrazyl (DPPH). Activity-guided fractionation led to the isolation of 6-methylluteolin, luteolin-7-O-beta-D-glucopyranoside, chlorogenic acid, ferulic acid, feruloyl-6-O-beta-D-glucopyranoside and maltol-beta-D-glucopyranoside.

Antioxidants↗
PubMed2004

Relevance of apple polyphenols as antioxidants in human plasma: contrasting in vitro and in vivo effects.

Apples are a major source of flavonoids in the Western diet, and flavonoid-rich foods may help protect against chronic diseases by antioxidant mechanisms. In the present study we investigated: (1) the antioxidant capacity of representative apple polyphenols and their contribution to the total antioxidant capacity of apple extracts; (2) the effects of adding apple extract to human plasma in vitro on oxidation of endogenous antioxidants and lipids; and (3) the effects of apple consumption by humans on ex vivo oxidation of plasma antioxidants and lipids. We found that the apple-contained flavonols and flavanols, quercetin, rutin, (-)-epicatechin, and (+)-catechin, had a higher antioxidant capacity than the dihydrochalcones, phloridzin and phloretin, and the hydroxycinnamate, chlorogenic acid. However, together these apple polyphenols contributed less than 20% to the total antioxidant capacity of aqueous apple extracts. When human plasma was exposed to a constant flux of aqueous peroxyl radicals, endogenous ascorbate (70.0 +/- 10.3 microM) was oxidized within 45 min of incubation, while endogenous urate (375 +/- 40 microM) and alpha-tocopherol (24.7 +/- 1.2 microM) were oxidized after ascorbate. Addition of 7.1 or 14.3 micrograms/ml total phenols of apple extract did not protect ascorbate from oxidation, but increased the half-life (t1/2) of urate from 136 +/- 15 to 192 +/- 16 and 208 +/- 23 min, respectively (p < 0.05 each), and t1/2 of alpha-tocopherol from 141 +/- 18 to 164 +/- 8 min (p = ns) and 188 +/- 8 min (p < 0.05). Lipid peroxidation started after ascorbate depletion, and addition of apple extract increased the lag time preceding detectable lipid peroxidation from 36.3 +/- 3.7 to 50.9 +/- 2.7 min (p < 0.05) and 70.4 +/- 4.2 min (p < 0.001). However, when six healthy volunteers ate five apples and plasma was obtained up to 4 h after apple consumption, no significant increases in the resistance to oxidation of endogenous urate, alpha-tocopherol, and lipids were found. Thus, despite the high antioxidant capacity of individual apple polyphenols and apple extracts and the significant antioxidant effects of apple extract added to human plasma in vitro, ingestion of large amounts of apples by humans does not appear to result in equivalent in vivo antioxidant effects of apple polyphenols.

Amidines↗
PubMed2004

Metabolite profiling and chemopreventive bioactivity of plant extracts from Bidens pilosa.

Bidens pilosa has been used as a folk medicine in various medications and as a popular ingredient in herb teas. Chemopreventive activities of crude and fractionated plant extracts of Bidens pilosa were evaluated in this study. Ethyl acetate and butanolic fractions, partitioned from the total crude extract of Bidens pilosa, exhibited significant scavenging free radical activity (IC(50) values approximately = with 14-17 microg/mL) comparable to that of alpha-tocopherol. Strong effects on the inhibition of LPS-mediated nitric oxide production in RAW 264.7 cells were also observed for the EA and BuOH fractions. Detectable cytotoxicity on RAW 264.7 cells, however, was observed for the EA fraction at a dose >100 microg/ml. The metabolite profile and major constituents of the BuOH fraction were studied and characterized using various spectroscopic analyses. A new compound, heptanyl 2-O-beta-xylofuranosyl-(1-->6)-beta-glucopyranoside (1), and eight phenolic compounds, namely quercetin 3-O-rabinobioside (2), quercetin 3-O-rutinoside (3), chlorogenic acid (4), 3,4-di-O-caffeoylquinic acid (5), 3,5-di-O-caffeoylquinic acid (6), 4,5-di-O-caffeoylquinic acid (7), jacein (8), centaurein (9) were for the first time isolated from Bidens pilosa. Compounds 2-7 are the major antioxidative constituents in the Bidens pilosa extract.

Animals↗
PubMed2006

Antioxidant activity of caffeoyl quinic acid derivatives from the roots of Dipsacus asper Wall.

The methanol extract from Dipsacus asper Wall (Dipsacaceae) was found to show antioxidant activity against free radical and Cu(2+)-mediated LDL oxidation. In further study, to identify active constituents from the plant, six caffeoyl quinic acid derivatives: 3,4-di-O-caffeoylquinic acid (1), methyl 3,4-di-O-caffeoyl quinate (2), 3,5-di-O-caffeoylquinic acid (3), methyl 3,5-di-O-caffeoyl quinate (4), 4,5-di-O-caffeoylquinic acid (5) and methyl 4,5-di-O-caffeoyl quinate (6) were isolated. Their structures were identified by spectroscopic methods including 2D-NMR. The isolated compounds, 1-6, were found to be potent scavengers of the free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH), and are more potent than butylated hydroxyl toluene (BHT) used as a positive control. The compounds 1-6 also inhibited Cu(2+)-mediated low-density lipoprotein (LDL) oxidation. They increased the lag time of conjugated dienes formation and inhibited the generation of thiobarbituric acid reactive substances (TBARS) in a dose-dependent manner. These results suggested that Dipsacus asper due to its antioxidant constituents, 1-6, may have a role to play in preventing the development and progression of atherosclerotic disease.

Antioxidants↗
PubMed2004

High-resolution method for regulatory control of Echinacea species in Nutraceuticals by CD-MEKC.

One problem in the international regulatory control of Echinacea, a therapeutic Nutraceutical, is recognition of caffeoyl solutes and alkamides in different products. Cyclodextrin-modified micellar electrokinetic chromatography (CD-MEKC) has been applied to Echinacea spp. in combination with pattern recognition of some caffeoyl solutes. A novel metric based on relative migration time (RMT) data has been developed in CE to address the problem of variable reported migration time. The CD-MEKC method of Gotti's group using hydroxypropyl-beta-cyclodexrin (HP-beta-CD; 100 mM) with sodium dodecyl sulphate (SDS; 110 mM), in a triacid background electrolyte (10 mM, pH 8) under 19 kV was adapted to identify two key hydrophilic solutes: chlorogenic acid and cichoric acid present in all commercial products. Two internal markers were taken as reference points to calculate the RMT of any target peak: RMT=t(m (target))/t(m (marker)). The RMT method was robust to temperature change from 20 to 40 degrees C, but sensitive to pH. The lateral shift and reproducibility of the target peak t(m (target)) were significantly reduced by this novel transformation. In the worst cases migration time variability ranged up to 12% (n=6); the RMT algorithm reduced this to less than 1%. In general, the RMT transformation reduced the variability of migration time data by a factor of 2-5. For systematic comparison of electrophoretic profiles for test sample and standard, a new pattern recognition algorithm permits sequential peak-by-peak comparison using specified segments of the electropherograms for comparison of test and Echinacea purpurea (root product) as a standard. This algorithm was capable of rapidly characterising the similarity of target peaks in a test sample relative to those in the reference standard. Combination of the RMT algorithm and pattern recognition in CE is expected to offer a robust approach to international regulatory characterisation and control of Nutraceuticals.

Chromatography, Micellar Electrokinetic Capillary↗
PubMed2006

Reduction in hypericin-induced phototoxicity by Hypericum perforatum extracts and pure compounds.

Clinical evidence suggests that administration of Hypericum perforatum (Hp) extracts containing the photo-activated hypericin compounds may cause fewer skin photosensitization reactions than administration of pure hypericin. This study was conducted to determine whether the phototoxicity of hypericin in HaCaT keratinocytes could be attenuated by H. perforatum extracts and constituents. Two extracts, when supplemented with 20 microM hypericin: (1) an ethanol re-extraction of residue following a chloroform extraction (denoted ethanol(-chloroform)) (3.35 microM hypericin and 124.0 microM total flavonoids); and (2) a chloroform extract (hypericin and flavonoids not detected), showed 25% and 50% (p<0.0001) less phototoxicity than 20 microM hypericin alone. Two H. perforatum constituents, when supplemented with 20 microM hypericin: (1) 10 microM chlorogenic acid; and (2) 0.25 microM pyropheophorbide, exhibited 24% (p<0.05) and 40% (p<0.05) less phototoxicity than 20 microM hypericin alone. The peroxidation of arachidonic acid was assessed as a measure of oxidative damage by photo-activated hypericin, but this parameter of lipid peroxidation was not influenced by the extracts or constituents. However alpha-tocopherol, a known antioxidant also did not influence the amount of lipid peroxidation induced in this system. These observations indicate that hypericin combined with H. perforatum extracts or constituents may exert less phototoxicity than pure hypericin, but possibly not through a reduction in arachidonic acid peroxidation.

Anthracenes↗
PubMed2005

Nutraceutical resources for diabetes prevention--an update.

There is considerable need for safe agents that can reduce risk for diabetes in at-risk subjects. Although certain drugs--including metformin, acarbose, and orlistat--have shown diabetes-preventive activity in large randomized studies, nutraceuticals have potential in this regard as well. Natural agents which slow carbohydrate absorption may mimic the protective effect of acarbose; these include: soluble fiber--most notably glucomannan; chlorogenic acid--likely responsible for reduction in diabetes risk associated with heavy coffee intake; and legume-derived alpha-amylase inhibitors. There does not appear to be a natural lipase inhibitor functionally equivalent to orlistat, although there are poorly documented claims for Cassia nomame extracts. Metformin's efficacy reflects activation of AMP-activated kinase; there is preliminary evidence that certain compounds in barley malt have similar activity, without the side effects associated with metformin. In supraphysiological concentrations, biotin directly activates soluble guanylate cyclase; this implies that, at some sufficient intake, biotin should exert effects on beta cells, the liver, and skeletal muscle that favor good glucose tolerance and maintenance of effective beta cell function. Good magnesium status is associated with reduced diabetes risk and superior insulin sensitivity in recent epidemiology; ample intakes of chromium picolinate appear to promote insulin sensitivity in many individuals and improve glycemic control in some diabetics; calcium/vitamin D may help preserve insulin sensitivity by preventing secondary hyperparathyroidism. Although conjugated linoleic acid--like thiazolidinediones, a PPAR-gamma agonist--has not aided insulin sensitivity in clinical trials, the natural rexinoid phytanic acid exerts thiazolidinedione-like effect in animals and cell cultures, and merits clinical examination. Other natural agents with the potential to treat and possibly prevent diabetes include extracts of bitter melon and of cinnamon. Nutraceuticals featuring meaningful doses of combinations of these agents would likely have substantial diabetes-preventive efficacy, and presumably could be marketed legally as aids to good glucose tolerance and insulin sensitivity.

Clinical Trials as Topic↗
PubMed2004

Homologous expression of the feruloyl esterase B gene from Aspergillus niger and characterization of the recombinant enzyme.

The faeB gene encoding the feruloyl esterase B (FAEB) was isolated from Aspergillus niger BRFM131 genomic DNA. The faeB gene, with additional sequence coding for a C-terminal histidine tag, was inserted into an expression vector under the control of the gpd promoter and trpC terminator and expressed in a protease deficient A. niger strain. Homologous overproduction allows to reach an esterase activity of 18 nkat mL(-1) against MCA as substrate. The improvement factor was 16-fold higher as compared to the production level obtained with non-transformed A. niger strain induced by sugar beet pulp. The corresponding secretion yield was estimated to be around 100 mg L(-1). Recombinant FAEB was purified 14.6-fold to homogeneity from an 8-day-old culture by a single affinity chromatographic step with a recovery of 64%. SDS-PAGE revealed a single band with a molecular mass of 75 kDa, while under non-denatured conditions, native enzyme has a molecular mass of around 150 kDa confirming that the recombinant FAEB is a homodimer. The recombinant and native FAEB have the same characteristics concerning temperature and pH optima, i.e., 50 degrees C and 6, respectively. In addition, the recombinant FAEB was determined to be quite stable up to 50 degrees C for 120 min. Kinetic constants for MCA, MpCA, and chlorogenic acid (5-O-caffeoyl quinic acid) were as follows: Km: 0.13, 0.029, and 0.16 mM and Vmax: 1101, 527.6, and 28.3 nkat mg(-1), respectively. This is the first report on the homologous overproduction of feruloyl esterase B in A. niger.

Aspergillus niger↗
PubMed2004

Agrobacterium tumefaciens AK-6b gene modulates phenolic compound metabolism in tobacco.

The 6b gene (AK-6b) of Agrobacterium tumefaciens AKE10 can substitute for the requirement of tobacco tissues for auxin and cytokinin to maintain callus growth in the culture medium. To identify compounds that might be involved in this process we analyzed phenolic metabolites in transgenic tobacco tissues expressing the AK-6b gene. On medium containing both cytokinin and auxin (SH medium), transgenic calli accumulated higher levels of chlorogenic acid, caffeoyl putrescine, rutin and kaempferol-3-rutinoside, than did wild-type tissues. In contrast, the levels of scopolin and its aglycone, scopoletin were lower in transgenic tissues. On hormone-free medium, these phenolic compounds showed neither significant levels nor an apparent relationship with AK-6b transcript levels, except for the negatively correlated levels of scopoletin and AK-6b transcripts. Apparently, the AK-6b gene acts, in SH medium, to redirect the synthesis of scopolin in tobacco tissues towards the preferential synthesis of caffeic acid derivatives and flavonoids.

Agrobacterium tumefaciens↗