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PubMed2005

A comparison of the cyclooxygenase inhibitor-NO donors (CINOD), NMI-1182 and AZD3582, using in vitro biochemical and pharmacological methods.

Cyclooxygenase (COX, EC 1.14.99.1) inhibitor-nitric oxide (NO) donor (CINOD) hybrid compounds represent an attractive alternative to NSAID and coxib therapy. This report compares two CINODs, NMI-1182 (naproxen-glyceryl dinitrate) and AZD3582 (naproxen-n-butyl nitrate), for their ability to inhibit COX-1 and -2, deliver bioavailable nitric oxide, and release naproxen, using in vitro biochemical and pharmacological methods. In human whole blood, both CINODs showed inhibition, comparable to naproxen, of both COX isozymes and slowly released naproxen. Both CINODs donated bioavailable NO, as detected by cGMP induction in the pig kidney transformed cell line, LLC-PK1, but NMI-1182 was more potent by 30-100 times than AZD3582, GTN, GDN, and ISDN and considerably faster in inducing cGMP synthesis than AZD3582. The nitrate groups of GTN, NMI-1182, and AZD3582 appeared to be bioactivated via a common pathway, since each compound desensitized LLC-PK1 cells to subsequent challenge with the other compounds. Similar cGMP induction also occurred in normal, untransformed cells (human renal proximal tubule epithelial cells and hepatocytes from man, rat, and monkey); again, NMI-1182 was superior to AZD3582. NMI-1182 was also the more metabolically labile compound, releasing more absolute nitrate and nitrite (total NO(x)) in human stomach (in which NO is salutary) and liver S9 homogenates. Naproxen was also more rapidly freed from NMI-1182 than AZD3582 in human stomach, although liver S9 hydrolyzed both CINODs with similar rates. These in vitro tests revealed that NMI-1182 may be a better CINOD than AZD3582 because of its superior NO donating and naproxen liberating properties.

Cyclic GMP↗
PubMed2006

Comparison of the concentrations of phenolic compounds in olive oils and other plant oils: correlation with antimicrobial activity.

The antimicrobial activity of different edible vegetable oils was studied. In vitro results revealed that the oils from olive fruits had a strong bactericidal action against a broad spectrum of microorganisms, this effect being higher in general against Gram-positive than Gram-negative bacteria. Thus, olive oils showed bactericidal activity not only against harmful bacteria of the intestinal microbiota (Clostridium perfringens and Escherichia coli) also against beneficial microorganisms such as Lactobacillus acidophilus and Bifidobacterium bifidum. Otherwise, most of the foodborne pathogens tested (Listeria monocytogenes, Staphylococcus aureus, Salmonella enterica, Yersinia sp., and Shigella sonnei) did not survive after 1 h of contact with olive oils. The dialdehydic form of decarboxymethyl oleuropein and ligstroside aglycons, hydroxytyrosol and tyrosol, were the phenolic compounds that statistically correlated with bacterial survival. These findings were confirmed by testing each individual phenolic compound, isolated by HPLC, against L. monocytogenes. In particular, the dialdehydic form of decarboxymethyl ligstroside aglycon showed a potent antimicrobial activity. These results indicate that not all oils classified as "olive oil" had similar bactericidal effects and that this bioactivity depended on their content of certain phenolic compounds.

Anti-Infective Agents↗
PubMed2005

N-Methylthio beta-lactam antibacterials: effects of the C3/C4 ring substituents on anti-MRSA activity.

N-Thiolated beta-lactams are a new family of antibacterials that inhibit the growth of Staphylococcus bacteria. Unlike other beta-lactam drugs, these compounds retain their full antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA) strains and operate through a different mode of action. The structural features, which give these lactams their biological activity, have not yet been completely defined. Earlier efforts in our laboratory established that the N-organothio substituent is essential for antimicrobial activity while other groups at C(3) and C(4) on the lactam ring play a more subtle role. In this present study, we investigate these effects by varying the polar and steric nature of the ring substituents at these two centers. From the data presented herein, it appears that there is a need to balance the lipophilic character of the C(3)/C(4) groups to obtain an optimal anti-MRSA activity. The structure-bioactivity profiles more closely relate to the compound's ability to penetrate the bacterial cell membrane to sites of action within the cytoplasm rather than to any specific non-bonding interactions with a biological target. Based on these results, a model for the compounds' mode of action is presented.

Anti-Bacterial Agents↗
PubMed1978

[Environmental carcinogens: mechanisms of action and occurrence. Some aspects (author's transl)].

New aspects on the mechanism of action of known environmental carcinogens are described. These compounds are not active as such, but are bioactivated in the mammalian metabolism via chemically reactive intermediates to electrophilic reactants, forming with information-bearing biopolymeres covalent bonds. This change in the genetic code is in agreement with the mutation hypothesis of carcinogenesis. Aflatoxin B1, N-nitroso compounds and benzo(a)pyrene are taken as examples. "Threshold levels", e.g. no-effect-levels derived from animal experiments with all their inherent limitations, are compared with data from human exposure to benzo(a)pyren, aflatoxine, N-nitroso compounds and vinyl chloride. The difficulties of such risk evaluations are discussed.

Aflatoxins↗
PubMed1987

Requirement of a properly acylated beta(1-6)-D-glucosamine disaccharide bisphosphate structure for efficient manifestation of full endotoxic and associated bioactivities of lipid A.

Several synthetic acylated glucosamine monophosphates, with structures corresponding to the nonreducing or reducing moiety of the lipid A of the Escherichia coli or Salmonella minnesota type, and a synthetic compound corresponding to a biosynthetic disaccharide lipid A precursor (designated Ia or IVA) were examined for their endotoxic and related bioactivities in comparison with those of the synthetic and bacterial parent molecules, i.e., acylated beta(1-6)-D-glucosamine disaccharide bisphosphates. Some of the test monosaccharide compounds were definitely active in most of the in vitro assays. Their activities, except for complement activation, however, were weaker than those of the reference compounds, synthetic and bacterial acylated disaccharide bisphosphates. The differences between the test monosaccharide and disaccharide compounds were much more apparent in in vivo assays, in which the test acylated glucosamine monophosphates were scarcely active, though some test compounds exhibited weak lethal toxicity in galactosamine-loaded mice and were weakly active in pyrogenicity, immunoadjuvant activity, and possible tumor necrosis factor and alpha and beta interferon-inducing ability in Mycobacterium bovis BCG- and Propionibacterium acnes-primed mice, respectively. Mixture at an equimolar ratio of acyl glucosamine monophosphates, each of which has the structure of the reducing or nonreducing moiety of the reference disaccharide compound, did not restore the endotoxic or associated bioactivities of the corresponding parent molecules. No essential differences in bioactivity were noted between synthetic and bacterial monosaccharide compounds, i.e., lipid X, whose structure corresponds to the reducing moiety of E. coli-type lipid A.

Acylation↗
PubMed1997

Pharmacologic approaches to protection against radiation-induced lethality and other damage.

Studies on mechanisms of radioprotection are leading to a more rational use of protectors for different applications. In considering the feasibility of radioprotectors that act through various mechanisms, it is necessary to distinguish the application needed, e.g., protection against accidental external or internal exposures, acute high-dose radiation injury or low doses over a long period, high-LET radiation exposures during space flight, and protection of normal tissues of cancer patients who are undergoing therapy. Protectors generally are classified as either sulfhydryl compounds, other antioxidants, or receptor-mediated agents (e.g., bioactive lipids, cytokines, and growth factors). This review focuses on comparative radioprotection and toxicity studies in mice using the most effective phosphorothioate agents designated as WR-compounds and other classes of protectors. The superiority of phosphorothioates (WR-2721, WR-151327) as radioprotectors appears to be related to their high affinity for DNA and the similarity in structure of phosphorothioate metabolites to polyamines, and their effects on processes related to DNA structure and synthesis. Drug tolerance levels are available from clinical trials using WR-2721 (amifostine) and provide a basis for discussions of the disadvantages of phosphorothioate administration outside a clinical setting. In this regard, arguments are presented against the current use of WR-2721 by Department of Energy personnel for planned radiation exposures during emergencies. Future research may demonstrate, however, that pharmacologic agents could be useful in accident scenarios, especially when used in combination with therapeutic measures. Assessment of potential prophylactic measures should consider compatibility with therapeutic measures currently in use or ones that might be available in the future for the treatment of radiation injuries. These include antiemetics, purified stem cells, granulocyte colony-stimulating factor, and other cytokines. Their potential usefulness against radiation-induced mutagenesis of pre- and postexposure administration of phosphorothioates and other classes of protectors should be corroborated in humans.

Amifostine↗
PubMed2005

Myxobacteria isolated in Israel as potential source of new anti-infectives.

AIMS: To evaluate the patterns of the production of antimicrobial compounds by Israeli myxobacteria newly isolated from soil samples and barks by a battery of isolation and purification methods. METHODS AND RESULTS: A total of 100 myxobacteria belonging to five of the 12 described genera, were isolated from 48 soil and 45 tree bark samples collected in different areas inside the State of Israel. Four isolation methods based on the peculiar metabolic and cell cycle aspects of myxobacteria, were combined with purification procedures and optimization of cultivation conditions. Ninety-seven strains were fermented and screened for antimicrobial activities. Production of antimicrobial activities was detected in 62 isolates. More than 50% of the collection (54 strains) was able to inhibit Escherichia coli growth. CONCLUSIONS: The results of this study support the idea that myxobacterial strains can be isolated from particular habitats and then cultivated and screened for their capacity to produce secondary metabolites endowed with antibacterial and antifungal activities. Myxovirescin, a typical poliketide myxobacterial antibiotic, has been identified in one Israeli isolate. Althiomycin, a thiazolyl peptide, which inhibits prokaryotic protein synthesis, usually produced by actinomycetes, was detected in three strains selected in this study. SIGNIFICANCE AND IMPACT OF THE STUDY: The results confirm that myxobacteria are prolific producers of a variety of bioactive secondary metabolites including antibacterial and antifungal compounds, being their high frequency of anti-Gram-negative activities particularly appealing for the current anti-infective research. So far their screening has often been hampered because their isolation is time-consuming and are quite difficult to handle and cultivate. In this paper we demonstrate that a proper combination of isolation, purification and cultivation methods allow their pharmaceutical exploitation.

Anti-Bacterial Agents↗
PubMed1992

Comparative molecular field analysis of polyhalogenated dibenzo-p-dioxins, dibenzofurans, and biphenyls.

Comparative molecular field analysis (CoMFA) was performed on polyhalogenated dibenzo-p-dioxins, dibenzofurans, and biphenyls for Ah (dioxin) receptor binding and associated enzyme inducing activities determined by others using in vitro assays. Since various members of all three classes of compounds have been shown to produce qualitatively similar toxicities, a separate CoMFA was performed on each class of compounds and combinations of the different classes for each bioactivity which included combining all three classes of molecules in one CoMFA study. For the Ah receptor binding, the CoMFA-derived QSARs for all three classes of compounds and combinations thereof showed strong crossvalidated correlations indicating that they are highly predictive. For enzyme induction, the CoMFA-derived QSARs were highly predictive for the dibenzofurans but were only partially successful for the dioxins. For the biphenyls, the results were clearly unpredictive. The overall results of these CoMFA studies which include both steric and electrostatic considerations are compared and contrasted to other SAR models that have met with some success in making qualitative predictions about the potential for receptor binding and associated toxicity in these classes of compounds. The CoMFA-derived QSAR for the dioxin series of molecules in most cases significantly overestimates the enzyme inducing ability of the ortho-substituted biphenyls. This weak inducing activity of the o-biphenyls is, however, consistent with their relatively low dioxin-like toxicity as measured in other biological systems. Fundamentally different mechanisms may be operating in the expression of dioxin-like toxic responses for the o-biphenyls, and their direct, dioxin-like toxic equivalency perhaps needs to be reconsidered in this light.

Aryl Hydrocarbon Hydroxylases↗
PubMed2004

On-line identification of phenanthroindolizidine alkaloids in a crude extract from Tylophora atrofolliculata by liquid chromatography combined with tandem mass spectrometry.

Electrospray ionization multi-stage tandem mass spectrometry (ESI-MS(n)) and liquid chromatography coupled with sequential mass spectrometry (LC/MS(n)) were applied to identify trace-level phenanthroindolizidine alkaloids in crude extracts from Tylophora atrofolliculata. Based on the relationship between the characteristic fragmentation reactions and the structural features of related compounds of known structure from this plant, the bioactive crude extract was analyzed in detail by positive and negative ion ESI-MS(n), LC/UV-MS and LC/MS(n) techniques. A total of nine constituents in the crude extract were identified rapidly, including several isomers; seven of these constituents are new and two are known compounds. The structures of four of these constituents were subsequently confirmed by nuclear magnetic resonance (NMR) and accurate mass measurements using high-resolution fast-atom bombardment mass spectrometry (FAB-HRMS).

Alkaloids↗
PubMed2005

Reagentless biosensor for phenolic compounds based on tyrosinase entrapped within gelatine film.

A simple and new reagentless phenolic compound biosensor was constructed with tyrosinase immobilized in the gelatine matrix cross-linked with formaldehyde. The morphologies of gelatine and gelatine/tryosinase were characterized by SEM. The tyrosinase retains its bioactivity when being immobilized by the gelatine film. Phenolic compounds were determined by the direct reduction of biocatalytically liberated quinone at -0.1 V vs SCE. The process parameters for the fabrication of the enzyme electrode were studied. Optimization of the experimental parameters has been performed with regard to pH, operating potential, temperature and storage stability. This biosensor exhibits a fast amperometric response to phenolic compounds. The linear range for catechol, phenol, and p-Cresol determination was from 5 x 10(-8) to 1.4 x 10(-4) M, 5 x 10(-8) to 7.1 x 10(-5)M, and 1 x 10(-7) to 3.6 x 10(-5)M, with a detection limit of 2.1 x 10(-8) M, 1.5 x 10(-8) M, and 7.1 x 10(-8 )M, respectively. The enzyme electrode retained ca.77% of its activity after 7 days of storage at 4 degrees C in a dry state. The proposed sensor presented good repeatability, evaluated in terms of relative standard deviation (R.S.D.=8.6%) for eight different biosensors and was applied for determination in water sample. The recovery for the sample was from 99.0% to 99.8%.

Benzoquinones↗
PubMed1984

Metabolic activation and lung toxicity: a basis for cell-selective pulmonary damage by foreign chemicals.

The lungs may be exposed to potentially toxic metabolites that are either formed in situ or which are present in the circulation. Therefore, pulmonary injury may be a prominent effect of certain classes of chemicals that undergo bioactivation in the body. The specific types of lung cells damaged may depend upon factors such as preferential exposure or accumulation of parent compounds and/or metabolites, differences in cellular defense mechanisms, or the specific mechanism of activation of the toxicant. Prior knowledge about the metabolism, disposition and mechanism of bioactivation of a particular compound may allow prediction of the type of lung cell damage it is likely to produce. Conversely, morphological observations of characteristic types of cell-specific injury in the lung may suggest a likely biochemical mechanism of toxicity for the particular chemical involved.

Animals↗
PubMed1999

On the bioactive conformation of NAN-190 (1) and MP3022 (2), 5-HT(1A) receptor antagonists.

Structural modifications of 1, a postsynaptic 5-HT(1A) receptor antagonist, provided its flexible (8, 12) and rigid (7, 9, 11, 13) analogues. Compounds 7, 8, 9, and 11 showed high 5-HT(1A) receptor affinity (K(i) = 4-72 nM). They acted as 5-HT(1A) postsynaptic receptor antagonists, since, like 1, they inhibited the behavioral syndrome, i.e., flat body posture (FBP) and forepaw treading (FT), in reserpine-pretreated rats as well as the lower lip retraction (LLR) in rats, both induced by 8-hydroxy-2-(di-n-propylamino)tetralin hydrobromide (8-OH-DPAT), a 5-HT(1A) receptor agonist. Compound 12, which demonstrated high 5-HT(1A) receptor affinity (K(i) = 50 nM), revealed properties of a partial 5-HT(1A) receptor agonist: it induced LLR and, at the same time, inhibited FT in rats. Compound 13 (K(i) = 1600 nM) was not tested in a behavioral study. Restriction of the conformational freedom in 2, a full 5-HT(1A) receptor antagonist, yielded compound 14 with high 5-HT(1A) receptor affinity (K(i) = 47 nM) and partial agonist properties at postsynaptic 5-HT(1A) receptors in the above tests in vivo; i.e., it induced LLR and inhibited FBP and FT in rats. New constrained analogues of 1 and 2 (compounds 7 and 14, respectively) were also synthesized to recognize a bioactive conformation of those 5-HT(1A) receptor antagonists. On the basis of in vitro and in vivo investigations, binding and functional properties of compound 7 were found to reflect those of 1 at 5-HT(1A) receptors. On the other hand, compound 14, a rigid analogue of 2, showed a different activity in vivo in comparison with the parent compound. PM3 and MM calculations revealed the existence of three low-energy conformers of 7 and six of 14, all of them belonging to the extended family of conformations. The optimized structures of both analogues had a different angle between aromatic planes of terminal fragments; moreover, the heteroaromatic system of those molecules occupied various space regions. Our present study provides support to the hypothesis that the bioactive conformation of 1, responsible for its postsynaptic 5-HT(1A) receptor antagonism, is an extended linear structure represented by 7.

Animals↗
PubMedDate not supplied

Low-dose bioactivity of xenoestrogens in animals: fetal exposure to low doses of methoxychlor and other xenoestrogens increases adult prostate size in mice.

The hormonal activity of natural estrogens is influenced by the degree to which they bind to serum proteins. In the pregnant female and in the fetus, greater than 99% of estradiol may be bound by serum binding proteins. Therefore, even though total serum levels of estradiol appear very high in fetuses, we have found that in rodent fetuses, there is a very low free concentration of estradiol (0.2 pg/ml). Naturally occurring variation in fetal serum estradiol predicts differences in numerous postnatal traits, including prostate size. In addition, when this low level of free estradiol was experimentally increased from 0.2 to 0.3 pg/ml during the last third of fetal life, treated male mice showed an increase in adult prostate weight. Fetal exposure to low doses of xenobiotic estrogens by feeding to pregnant females, including the compounds methoxychlor (20 and 2000 micrograms/kg body weight), DES (0.02 to 2 micrograms/kg body weight) and bisphenol A (2 and 20 micrograms/kg body weight), also led to increased prostate weight in adulthood. In contrast, fetal doses of natural estradiol and DES above the physiological range of estrogenic activity, and within a toxicological dose range, led to the opposite outcome, a reduction in subsequent adult prostate weight. This indicates that it may be impossible to assess endocrine-disrupting activities in response to low doses within a physiological range of activity by using high, toxic doses of xenoestrogens in testing procedures. We have developed approaches in vitro to predict the potential estrogenic bioactivity of compounds in the physiologically relevant range in animals and humans. We address the following factors in predicting the final observed endocrine-disrupting effect in the animal: (1) the intrinsic estrogenic activity of a given molecule, (2) the effective free concentration determined by how the molecule is carried in serum, (3) partitioning between aqueous and lipid compartments in body and cell lipids, and (4) absorption and metabolism relative to the route of exposure. The studies and strategies we describe are important in developing criteria for a tiered testing system for the detection of estrogenic chemicals as well as endocrine-disrupting chemicals with different modes of action.

Animals↗
PubMed2002

Comparative study on the bioactivation mechanisms and cytotoxicity of Te-phenyl-L-tellurocysteine, Se-phenyl-L-selenocysteine, and S-phenyl-L-cysteine.

Tellurium compounds are effective antioxidants and chemoprotectors, even more active than their selenium and sulfur analogues. In addition to these properties, some selenium compounds, such as selenocysteine Se-conjugates, possess significant chemopreventive and antitumor activities, and selenol metabolites are considered as active species. In the present study, we have synthesized Te-phenyl-L-tellurocysteine and evaluated its bioactivation and cytotoxicity. The activities of this compound were compared with those of the corresponding selenium and sulfur analogues. Te-Phenyl-L-tellurocysteine is bioactivated into its corresponding tellurol, as detected by GC-MS, by cysteine conjugate beta-lyase and amino acid oxidase, analogously to what has been shown previously for Se-phenyl-L-selenocysteine. The rate of beta-elimination may reflect the bond strength of the corresponding C-S, C-Se, and C-Te bond. Bioactivation of Te-phenyl-L-tellurocysteine and its selenium and sulfur analogues by oxidative enzymes was evaluated by measuring NADPH-dependent activation of hepatic mGST and inhibition of EROD. Te-Phenyl-L-tellurocysteine and Se-phenyl-L-selenocysteine displayed strong and time-dependent mGST activation, while S-phenyl-L-cysteine resulted in no significant activation. Te-Phenyl-L-tellurocysteine was also a strong inhibitor of EROD activity. In addition to EROD inhibition, Te-phenyl-L-tellurocysteine was the strongest inhibitor of several human cytochrome P450 isoenzymes followed by Se-phenyl-L-selenocysteine, while S-phenyl-L-cysteine was the weakest inhibitor. Interestingly, Te-phenyl-L-tellurocysteine selectively inhibited cytochrome P450 1A1 directly, which is, for example, responsible for the activation of several procarcinogens. Preliminary cytotoxicity studies with Te-phenyl-L-tellurocysteine in freshly isolated rat hepatocytes showed a time-dependent depletion of GSH and LDH leakage comparable with the relatively nontoxic drug paracetamol, while the selenium and sulfur analogues were nontoxic toward rat hepatocytes. In conclusion, because the chemopreventive and antitumor activities of selenium compounds are thought to be mediated via their selenol metabolites and tellurium compounds might be even more active than selenium compounds, tellurocysteine Te-conjugates might be an interesting novel class of prodrugs for the formation of biologically active tellurols.

Animals↗
PubMed2005

Larvicidal activity of Acacia nilotica extracts and isolation of D-pinitol--a bioactive carbohydrate.

A low-molecular-weight, sugar-like compound other than glucose, fructose, sucrose, or myo-inositol showing lipophilic nature was isolated from the EtOH extract of Acacia nilotica. The structure of the compound was determined by spectral methods. This alicyclic polyalcohol was found to be D-pinitol (= 3-O-methyl-D-chiro-inositol; 1). The configuration of the compound was confirmed by single-crystal X-ray analysis. The compound 1 is known from Soybean, Australian mangroves, Fagonia indica, Arachis hypogaea, etc., but we have isolated this compound for the first time from the aerial parts of A. nilotica. Very few references have been cited for compound 1 for its entomological activity, and there are no reports on mosquitoes. Therefore, the crude extracts of A. nilotica were tested for its biological activity against mosquito larvae. Acetone extract at 500-ppm concentration showed chronic toxicity against Aedes aegypti and Culex quinquefasciatus IVth instar mosquito larvae. Such a biological activity has been observed for the first time for this plant. This study could be a stepping stone to a solution for destroying larval species as well as consumption of such a widely grown, problem weed, A. nilotica. This larvicidal agent, since it is derived from plant, is eco-friendly, cost effective, non-hazardous to non-target organisms and would be safe unlike commercially available insecticides.

Acacia↗
PubMed2005

In vitro tests and ethnopharmacological investigations: wound healing as an example.

In vitro tests are now widely employed in ethnopharmacological research because of ethical reasons and their usefulness in bioactive-guided fractionation and determination of active compounds. For many disease conditions, a variety of in vitro tests can now be employed as the biochemical mechanisms underlying disease and healing processes are understood. Approaches to the in vitro investigations of wound healing processes are exemplified by studies on extracts of Buddleja species and three Ghanaian species Spathodea campanulata, Commelina diffusa and Secamone afzelii. Most studies have been carried out on Buddleja officinalis or Buddleja globosa. The extracts have been shown to have anti-inflammatory and antioxidant properties due to flavonoids, triterpenoids, diterpenoids and caffeic acid derivatives. There appears to a slight effect on proliferation of fibroblasts at lower concentrations, but this was not significant, and higher concentrations appeared to be cytotoxic. Novel findings are the ability of Buddleja globosa leaf extracts to induce differentiation in keratinocytes and to alter the profile of proteins produced by cultured fibroblasts. Extracts also had some effect on lattice contraction. The three Ghanaian species examined show a mixture of antimicrobial and antioxidant activities. The evolution over recent years of tests for wound healing, from in vivo tests to cell-based systems and chemical reactions and on to investigations into effects on secondary messengers and protein expression, is described.

Animals↗
PubMed2004

Molecular imaging of the biological effects of quercetin and quercetin-rich foods.

The human diet contains several thousands of organic plant molecules (i.e. phytochemicals), many of which have significant bioactivities. The specific physiological effects of these compounds are impossible to predict from in vitro studies using cell cultures and cell-free model systems. Nutrigenomics, which may be defined as the application of genomic tools to study the integrated effects of nutrients on gene regulation, however, holds great promise in increasing the understanding of how nutrients affect molecular events in an organism. Quercetin, a phytochemical belonging to the flavonoids, has antioxidant activities, inhibit protein kinases, inhibit DNA topoisomerases and regulate gene expression. The aim of the present review is to describe some of the many effects of quercetin, and how molecular imaging using transgenic reporter mice may serve as a tool to study the integrated influence of quercetin and other dietary phytochemicals on gene expression in vivo. We are using the bioluminescence emitted from firefly luciferase as the reporter since light originating from the inside of a cell or organism can be detected externally in an intact living organism. Molecular imaging using reporter models is therefore a unique technology to study the integrated effects of environmental insults and dietary substances on the influence of gene expression in disease development. We utilize these in vivo models to elucidate the role of various flavonoids, such as quercetin, for modulating gene expression related to oxidative stress and the antioxidant defence system.

Animals↗
PubMed2000

On-line identification of phytochemical constituents in botanical extracts by combined high-performance liquid chromatographic-diode array detection-mass spectrometric techniques.

It is necessary to determine all of the phytochemical constituents of botanical extracts in order to ensure the reliability and repeatability of pharmacological and clinical research, to understand their bioactivities and possible side effects of active compounds and to enhance product quality control. HPLC chromatographic fingerprints can be applied for this kind of documentation. Combined HPLC-diode array detection-MS techniques can provide on-line UV and MS information for each peak in a chromatogram. In most cases, direct identification of the peaks is possible, based on comparison with published data or with standard compounds. This review will primarily focus on electrospray and thermospray ionization MS and their applications for the qualitative analyses of phenolic compounds, saponins, alkaloids and other classes of natural products in botanical extracts. Twenty-one of the most commonly used herbal examples, their phytochemical analyses and characteristics of their mass spectra are described.

Alkaloids↗