Inhibitory Effect of Selected Guaianolide and Germacranolide Sesquiterpene Lactones on Nitric Oxide Production.

Trilobolide and its analogues belong to the guaianolide type of sesquiterpene lactones, which are characteristic and widely distributed within the families Asteraceae and Apiaceae. Certain guaianolides are receiving continuously increasing attention for their promising sarco-endoplasmic reticulum Ca2+-ATPase (SERCA)-inhibitory activity. However, because of their alkylation capabilities, they are generally toxic. Therefore, the search for compounds with significant immunobiological properties but with decreased cytotoxicities suitable for use in immune-based pharmacotherapy is ongoing. Therefore, we extended our previous investigation of the immunobiological effects of trilobolide to a series of structurally related guaianolides and germacranolides. To evaluate the relationship, we tested a series of selected derivatives containing α-methyl lactone or exomethylene lactone ring. For a wider comparison, we also included some of their glycosidic derivatives. We assessed the in vitro immunobiological effects of the tested compounds on nitric oxide (NO) production, cytokine secretion, and prostaglandin E2 (PGE2) release by mouse peritoneal cells, activated primarily by lipopolysaccharide (LPS), and evaluated their viability. The inhibitory effects of the apparently most active substance, 8-deoxylactucin, seem to be the most promising.

Spirostanol Saponins from Flowers of Allium Porrum and Related Compounds Indicating Cytotoxic Activity and Affecting Nitric Oxide Production Inhibitory Effect in Peritoneal Macrophages.

Saponins, a diverse group of natural compounds, offer an interesting pool of derivatives with biomedical application. In this study, three structurally related spirostanol saponins were isolated and identified from the leek flowers of Allium porrum L. (garden leek). Two of them were identical with the already known leek plant constituents: aginoside (1) and 6-deoxyaginoside (2). The third one was identified as new component of A. porrum; however, it was found identical with yayoisaponin A (3) obtained earlier from a mutant of elephant garlic Allium ampeloprasun L. It is a derivative of the aginoside (1) with additional glucose in its glycosidic chain, identified by MS and NMR analysis as (2α, 3ß, 6ß, 25R)-2,6-dihydroxyspirostan-3-yl ß-D-glucopyranosyl-(1 → 3)-ß-D-glucopranosyl-(1 → 2)-[ß-D-xylopyranosyl-(1 → 3)]-ß-D-glucopyranosyl]-(1 → 4)-ß-D-galactopyranoside, previously reported also under the name alliporin. The leek native saponins were tested together with other known and structurally related saponins (tomatonin and digitonin) and with their related aglycones (agigenin and diosgenin) for in vitro cytotoxicity and for effects on NO production in mouse peritoneal cells. The highest inhibitory effects were exhibited by 6-deoxyaginoside. The obtained toxicity data, however, closely correlated with the suppression of NO production. Therefore, an unambiguous linking of obtained bioactivities of saponins with their expected immunobiological properties remained uncertain.

Polysubstituted 4,6-bis(hetero)arylpyrimidines as dual inhibitors of nitric oxide and prostaglandin E2 production.

As a part of our extensive structure-activity relationship study of anti-inflammatory heterocycles, a novel series of 67 polysubstituted 2-aminopyrimidines was prepared bearing one (at the C-4 position of the pyrimidine ring) or two (in the C-4 and C-6 positions) (hetero)aryl substituents attached directly through the C-C bond. The key synthetic steps involved either Suzuki-Miyaura or Stille cross-coupling reactions carried out on easily available 4,6-dichloropyrimidines. All prepared compounds, except one, were able to inhibit immune-activated production of nitric oxide (NO) significantly. Moreover, several compounds were found to be low micromolar dual inhibitors of NO and prostaglandin E2 (PGE2) production. Although the exact mode of action of the prepared compounds remains to be elucidated, non-toxic dual inhibitors of NO and PGE2 production may have great therapeutic benefit in treatment of various inflammation diseases and deserve further preclinical evaluation.

Dual inhibition of nitric oxide and prostaglandin E2 production by polysubstituted 2-aminopyrimidines.

The present in vitro experiments demonstrate inhibitory effects of polysubstituted 2-aminopyrimidines on high output production of nitric oxide (NO) and prostaglandin E2 (PGE2) stimulated by interferon-γ and lipopolysaccharide (LPS) in peritoneal macrophages of mouse and rat origin. PGE2 production was inhibited also in LPS-activated human peripheral blood mononuclear cells. A tight dependence of the suppressive activities on chemical structure of pyrimidines was observed. Derivatives containing hydroxyl groups at the C-4 and C-6 positions of pyrimidine ring were devoid of any influence on NO and PGE2. Remarkable inhibitory potential was acquired by the replacement of hydroxyl groups with chlorine, the 4,6-dichloro derivatives being more effective than the monochloro analogues. The effects were further intensified by modification of the amino group at the C-2 position, changing it to the (N,N-dimethylamino)methyleneamino or the formamido ones. There was no substantial difference in the expression of NO-inhibitory effects among derivatives containing distinct types of substituents at the C-5 position (hydrogen, methyl, ethyl, propyl, butyl, phenyl, and benzyl). In contrast to NO, larger substituents then methyl were required to inhibit PGE2 production. Overall, no significant correlation between the extent of NO and PGE2 suppression was observed. The IC50s of derivatives with the strongest effects on both NO and PGE2 were within the range of 2-10 µM. Their NO-inhibitory potential of pyrimidines was stronger than that of non-steroidal anti-inflammatory drugs (NSAIDs) aspirin and indomethacin. The PGE2-inhibitory effectiveness of pyrimidines was about the same as that of aspirin, but weaker as compared to indomethacin. The NO- and PGE2-inhibitory activity of tested pyrimidines has been found associated with decreased expression of iNOS mRNA and COX-2 mRNA, respectively, and with post-translation interactions. Selected NO-/PGE2-inhibitory derivatives decreased severity of intestinal inflammation in murine model of ulcerative colitis.

Acyclic nucleoside phosphonates: a study on cytochrome P450 gene expression.

1. Nucleotide analogues comprise an important class of drugs used in treatment of viral infections but also cancer. These drugs affect the structural integrity of DNA and activate different pathways and processes in the cell and may directly or indirectly influence the drug metabolizing system. Adefovir dipivoxil (AD) and tenofovir disoproxil (TD) are nucleotide analogues approved for the treatment of chronic hepatitis B and/or HIV/AIDS infection. 2. To evaluate the risk of their drug-drug interactions on the level of drug metabolism, an effect of both compounds on cytochromes P450 expression was studied using cDNA microarrays, real-time RT-PCR and immunoblotting. Mice were given intraperitoneally 25 mg/kg of AD or TD, respectively. As a positive control, a combination of prototypic cytochromes P450 (CYP) inducers, phenobarbital and ß-naphthoflavone was chosen. 3. The data obtained showed a significant CYP induction in the positive control group, but no clinically significant induction of CYP genes by AD or TD was observed. Our results support the evidence of safety of AD and TD with respect to drug-drug interactions based on enzyme induction. These findings are important as a plethora of new antivirals of different types are being tested and introduced to clinical practice, mostly to be used in combinations.

Activation of respiratory complex II by interferon-gamma and its inhibition by pyrimidine derivatives.

OBJECTIVES: Formation of formazan is a commonly used measure of cytotoxicity of compounds. It is a product of reduction of tetrazolium salts such as 4-[3- (4-iodophenyl)-2- (4-nitrophenyl)-2H-5-tetrazolio]-1,3-benzene disulfonate (WST-1) and 2-(4-iodophenyl)-3-(4-nitrophenyl)-5-phenyltetrazolium chloride. The extent of substrates reduction reflects the activity of enzymes succinate dehydrogenase (SDH; respiratory complex II) and lactate dehydrogenase (LDH), respectively. The aim of present study was a) to investigate formazan formation under the conditions of in vitro stimulation of cells with interferon-γ (IFN-γ) and lipopolysaccharide (LPS), and b) to analyse possible interference of pyrimidine analogues with formazan production. METHODS: Peritoneal cells and splenocytes were obtained from C57BL/6 mice. They were cultured at 37 degrees C, 5% CO2 in humidified incubator. Levels of formazan were determined at the interval of 24 h of culture using the WST-1 and LDH assays. Nitric oxide (NO) was activated by IFN-γ plus LPS and assayed by Griess reagent 24 h afterwards. Pyrimidines were applied concomitantly with immunostimulatory agents. RESULTS: IFN-γ enhanced concentration of SDH-produced formazan by macrophages (not by splenocytes) by approximately 50%. The activity of LDH remained unaffected. LPS was ineffective in both cases. While pyrimidines with NO-inhibitory properties suppressed the IFN-γ-enhanced levels of SDH-produced formazan, they did not change the LDH-dependent formazan production. CONCLUSION: IFN-γ augments the SDH-produced formazan by macrophages. It does not change the LDH-dependent formazan formation. The enhancing effect may have a significant impact upon the appropriate interpretation of cytotoxic properties of drugs investigated under the conditions of immune stimulation of cells.

5-Substituted 2-amino-4,6-dihydroxypyrimidines and 2-amino-4,6-dichloropyrimidines: synthesis and inhibitory effects on immune-activated nitric oxide production.

A series of 5-substituted 2-amino-4,6-dihydroxypyrimidines were prepared by a modified condensation of the corresponding monosubstituted malonic acid diesters with guanidine in an excess of sodium ethoxide. The optimized procedure using Vilsmeier-Haack-Arnold reagent, followed by immediate deprotection of the (dimethylamino)methylene protecting groups, has been developed to convert the 2-amino-4,6-dihydroxypyrimidine analogs to novel 5-substituted 2-amino-4,6-dichloropyrimidines in high yields. Pilot screening for biological properties of the prepared compounds was done in mouse peritoneal cells using the in vitro nitric oxide (NO) assay. Irrespective of the substituent at the 5 position, 2-amino-4,6-dichloropyrimidines inhibited immune-activated NO production. The most effective was 5-fluoro-2-amino-4,6-dichloropyrimidine with an IC 50 of 2 µM (higher activity than the most potent reference compound) while the IC 50s of other derivatives were within the range of 9-36 µM. The 2-amino-4,6-dihydroxypyrimidine counterparts were devoid of any NO-inhibitory activity. The compounds had no suppressive effects on the viability of cells. The Mechanism of action remains to be elucidated.

Microfiltration method of removal of bacterial contaminants and their monitoring by nitric oxide and Limulus assays.

Similar to lipopolysaccharide (LPS), a product of Gram-negative bacteria, the signal macromolecules of Gram-positive bacteria lipoteichoic acid (LTA) and peptidoglycan (PGN) possess multiple biological activities. They may be a source of misinterpretation of experimental findings. We have found that not only LPS but also LTA and PGN can be detected by the Limulus amebocyte lysate (LAL) assay. All of them stimulate the high output in vitro nitric oxide (NO) production of in rat peritoneal cells. The onset of the NO enhancement was observed with 25-100pg/ml of LPS and 25-100ng/ml of PGN and LTA. Polymyxin B (PMX), if applied at concentration 10,000-fold higher than that of LPS, can completely inhibit the NO and LAL binding responses of LPS. The NO-stimulatory and LAL-binding properties of LTA and PGN are not eliminated by PMX. Handling of LPS contamination with PMX may be associated with serious problems because it possesses intrinsic biological activity and becomes cytotoxic at concentration >25µg/ml. The present findings suggest a convenient alternative avoiding these issues. As monitored by the NO and LAL assays, even high amounts of LPS as well as PGN and LTA can be removed by molecular mass cutoff microfiltration. All types of the filters (3kDa to 100kDa) are equally effective. It is suggested that the microfiltration procedure may be considered as a preferable, general and easy method of sample decontamination.

The effect of probiotic Escherichia coli strain Nissle 1917 lipopolysaccharide on the 5-aminosalicylic acid transepithelial transport across Caco-2 cell monolayers.

The object of this study was to investigate the effect of probiotic Escherichia coli strain Nissle 1917 (EcN) (i) EcN lipopolysaccharide (EcN LPS) and (ii) bacteria-free supernatant of EcN suspension (EcN supernatant) on in vitro transepithelial transport of mesalazine (5-aminosalicylic acid, 5-ASA), the most commonly prescribed anti-inflammatory drug in inflammatory bowel disease (IBD). Effect of co-administered EcN LPS (100 µg/ml) or EcN supernatant (50 µg/ml) on the 5-ASA transport (300 µmol/l) was studied using the Caco-2 monolayer (a human colon carcinoma cell line) as a model of human intestinal absorption. Permeability characteristics for absorptive and secretory transport of parent drug and its intracellularly-formed metabolite were determined. The quantification of 5-ASA and its main metabolite N-acetyl-5-amino-salicylic acid (N-Ac-5-ASA) was performed by high performance liquid chromatography. Obtained results suggest that neither EcN LPS nor EcN supernatant had effect on the total 5-ASA transport (secretory flux greater than absorptive flux) and on the transport of intracellularly formed N-Ac-5-ASA (preferentially transported in the secretory direction). The percent cumulative transport of the total 5-ASA alone or in combination with EcN LPS or EcN supernatant did not exceed 1%.

Two new C-methyl flavanones from the rhizomes and frond bases of Matteuccia struthiopteris.

Two new C-methyl flavanones, (2S)-5,7-dihydroxy-6,8-dimethyl-4'-methoxydihydroflavone-7-O-(6″-O-acetyl)-ß-d-glucopyranoside (1) and (2S)-5,7-dihydroxy-6,8-dimethyldihydroflavone-7-O-(6″-O-acetyl)-ß-d-glucopyranoside (2), together with five known compounds, demethoxymatteucinol-7-O-ß-d-glucopyranoside (3), matteucinol-7-O-ß-d-glucopyranoside (4), 5,7-dihydroxy-6-methyl-4'-methoxydihydroflavone (5), methoxymatteucin (6), and thunberginol C (7), were first isolated from the EtOH extract of the rhizomes and frond bases of Matteuccia struthiopteris. The structures were established by spectral analyses, mainly HR-ESI-MS and 1D and 2D NMR experiments (COSY, HSQC, and HMBC).

Stimulation of nitric oxide, cytokine and prostaglandin production by low-molecular weight fractions of probiotic Lactobacillus casei lysate.

OBJECTIVES: Major medical indications of probiotic bacteria are conditions associated with the gastrointestinal tract. They exhibit not only the local but also systemic effects, the molecular mechanisms of which are poorly understood. We hypothesized that the action at remote sites of the body could be at least partially attributed to substances of the low molecular mass released from digested bacteria and able to cross the intestinal barrier. The aim of the study was the analysis of immunobiological properties of bacterial lysates and characterization of chemical constituents participating on this mode of action. METHODS: Lactobacillus casei probiotic strain DN-114001 was employed. Lysates were prepared by passing bacteria through a French press (1500 psi) followed by lyophilisation. The fractions were prepared by the microfiltration of the crude lysate using the 3-, 10-, 30-, 50-, and 100-kDa cutoff filters (Amicon® Ultra 0.5 ml, Millipore Corp.). This procedure completely removes biologically active bacterial macromolecules such as peptidoglycan (PGN), lipoteichoic acid (LTA) and lipopolysaccharide (LPS). Effects of microfiltrates on the in vitro production of nitric oxide (NO), cytokines, and prostaglandin E2 (PGE2) were investigated in rat peritoneal cells. RESULTS: The original crude lysate (≤10 µg/ml) activated the biosynthesis of NO, PGE2, and secretion of cytokines. The amount of the lysate needed for the preparation of microfiltered fractions exhibiting immunostimulatory effects was 10-fold higher (100 µg/ml). The molecules with the molecular mass ≤3 kDa were responsible for approximately 45% and 83% of the NO- and PGE2-enhancing activities of the crude lysate, respectively. The microfiltered fractions of the lysate also enhanced secretion of interleukin-6 and tumor necrosis factor-α but not that of interleukin-10 and interferon-γ. CONCLUSION: The Lactobacillus casei probiotic strain DN-114001 contains low molecular mass (≤3 kDa) molecules possessing immunostimulatory properties. Their chemical nature remains to be identified.

Effects of Lactobacillus casei on the expression and the activity of cytochromes P450 and on the CYP mRNA level in the intestine and the liver of male rats.

OBJECTIVES: The aim of the study was to find whether probiotic Lactobacillus casei influences the expression or the activity of cytochromes P450 (CYP) and whether it has an influence on the level of CYP mRNA in male rats. DESIGN: Live bacterial suspension of L. casei was administered orally (gavage) to healthy male Wistar rats daily for 7 days. Control group of rats was treated with the saline solution. Sections of the duodenum, jejunum, ileum, caecum and colon were dissected from each experimental animal. In all individual samples, the expression of selected CYPs was determined by Western blotting. The levels of expression of CYPs were also evaluated by mRNA using the real-time PCR method. RESULTS: There were changes observed in the expression of CYP enzymes and in the CYP mRNA levels along the intestine after application of L. casei. The expression of CYP1A1 enzyme was found to be decreased in the proximal part of the jejunum and colon, CYP1A1 mRNA level was decreased in the distal part of the jejunum, ileum and caecum. Thus, the changes in CYP1A1 protein or mRNA were observed along the intestine of male rats. Similarly, a decreased expression of the caecal CYP2E1 mRNA and of the duodenal CYP3A9 mRNA after treatment of rats with L. casei was found. CONCLUSION: Probiotic L. casei might be able to contribute to prevention against colorectal cancer by decreasing levels of certain forms of xenobiotic-metabolizing enzymes; moreover, in general, there is a possibility of interactions with concomitantly taken pharmacotherapeutic agents.

Polysubstituted Pyrimidines as Potent Inhibitors of Prostaglandin E2 Production: Increasing Aqueous Solubility.

Water solubility is one of the key features of potential therapeutic agents. In order to enhance the low water solubility of the parent 5-butyl-4-(4-methoxyphenyl)-6-phenylpyrimidin-2-amine, a potent inhibitor of prostaglandin E2 (PGE2 ) production, we synthesized and evaluated a new series of derivatives in which the butyl group at the C5 position of the pyrimidine ring was replaced with a less lipophilic substituent, preferably with a hydrophilic aliphatic moiety. Except for the 5-cyanopyrimidine derivative, all target compounds exhibited increased (2.7-87-fold) water solubility relative to the parent compound. Although nontoxic in mouse peritoneal cells, the prepared compounds were either equipotent or weaker inhibitors of PGE2 production than the parent compound. The most promising compound from the series was found to be the 5-(2,5,8,11-tetraoxadodecyl)pyrimidine derivative (with three polyethylene glycol units at the C5 position), which exhibited 32-fold higher water solubility and only slightly weaker inhibitory activity (22 % of remaining PGE2 production) compared with the parent compound (15 % of remaining PGE2 production).

Intrinsic nitric oxide-stimulatory activity of lipoteichoic acids from different Gram-positive bacteria.

Lipoteichoic acid (LTA) is a structural component of the cell walls of Gram-positive bacteria. Similar to lipopolysaccharide (LPS) which is expressed in Gram-negative bacteria, LTA exhibits immunostimulatory properties. Frequently observed positive response of LTA in the Limulus amebocyte lysate (LAL) assay has been interpreted as a sign of LPS contamination, raising doubts about the intrinsic immune activities of LTA. Regarding many similarities in immunobiological and physicochemical properties of LTA and LPS, we hypothesized that similar to LPS, the LAL reactivity of LTA might be due to its ability to bind to LAL. Our data confirm the positivity of Bacillus subtilis, Staphylococcus aureus, Streptococcus faecalis and Streptococcus pyogenes LTAs in the LAL test. The estimates of suspected LPS content were 605, 10.3, 6.2 and 127 pg/µg LTA, respectively. The effectiveness of LTAs to induce the NO production in rat peritoneal cells was remarkably higher than that of equivalent concentrations of reference LPS (Escherichia coli). The LPS-induced NO was inhibited by polymyxin B (PMX), the IC(50) of PMX:LPS concentration ratio (pg:pg) being 1050:1. Many fold higher concentrations of PMX were needed to partially suppress the NO-augmenting effects of LTAs, applied at concentrations representing the equivalents of LPS. Transposed to the concentrations of LTAs per se, the IC(50)s of the PMX:LTA ratios (µg:µg) ranged from 0.3:1 (S. aureus) to 7.5:1 (B. subtilis). It is concluded that LTA is not necessarily contaminated with LPS. The results prove the intrinsic immunostimulatory properties of LTAs of Gram-positive bacteria. The positive response of LTA in the LAL assay results from its capacity to bind to LAL. In addition, LTA binds with high affinity to PMX.

Caco-2 cell monolayer integrity and effect of probiotic Escherichia coli Nissle 1917 components.

OBJECTIVES: Different probiotic strains used in clinical trials have shown prophylactic properties in different inflammatory diseases of the gastrointestinal tract. This study was aimed to investigate the influence of Escherichia coli strain Nissle 1917 (EcN) components on the integrity of the Caco-2 cell monolayer (human adenocarcinoma cell line). METHODS: The effect of supernatant of EcN suspension and lipopolysaccharide (LPS) isolated from EcN (in concentrations from 0.001 to 1 000 µg/ml) on paracellular transport of 14C-mannitol marker through epithelial cell monolayer was estimated. RESULTS: Both LPS and EcN supernatant exerted almost the same effect; whereas no effect was shown using high concentrations (100 and 1 000 µg/ml), low concentrations (0.001, 0.1 and 1 µg/ml) significantly decreased permeability of 14C-mannitol. Concentration (0.001 µg/ml) decreased 14C-mannitol permeability approximately about 20% (LPS) and 30% (EcN supernatant). To elucidate the observed changes in monolayer permeability ("tighter monolayer") induced by concentrations of LPS or supernatant, media able to open epithelial intercellular junctions were used. The effects of Ca2+-free transport medium and of medium containing 5, 10, 20, 50, and 100% of Ca2+ on the 14C-mannitol transport in the presence of the lowest (0.001 µg/ml) and high (100 µg/ml) concentrations of LPS were studied. Using Ca2+-free medium both concentrations of LPS significantly decreased apparent permeability coefficient (Papp) of 14C-mannitol indicating that changes of 14C-mannitol permeability are independent of dimensions of paracellular spaces. CONCLUSION: The decrease of 14C-mannitol permeability caused by EcN LPS indicates the ability of components of probiotic EcN strain to restore disrupted epithelial barrier.

Effects of probiotic Escherichia coli Nissle 1917 on expression of cytochromes P450 along the gastrointestinal tract of male rats.

OBJECTIVES: The aim of the study was to find whether probiotic Escherichia coli Nissle 1917 O6:K5:H1 (EcN) influences the expression of cytochromes P450 (CYP) in the rat intestine. DESIGN: Live bacterial suspension of EcN was administered to healthy male Wistar rats daily for 7 days. Control group of rats was stressed by oral application of the saline solution daily for 7 days as well. Sections of the duodenum, jejunum, ileum, caecum and colon have been taken from each experimental animal. With all individual samples, microsomal fraction has been prepared and expression of selected CYPs was determined by Western blotting. The levels of expression of CYPs were also evaluated by mRNA using real-time PCR. RESULTS: It was found that there are changes in expression of CYP enzymes studied along the intestine. CYP1A1, 2B1/2 and 2E1 are present mainly in the duodenum and jejunum; on the other hand, CYP2C6 is expressed mainly in the caecum and colon. CYP3A was found all over the rat intestine. The results show that there are no prominent differences between control samples and samples with EcN, only the expression of CYP3A protein in the duodenum appears to exhibit a clear tendency to decrease. In the case of the colon, a significant increase in the expression of CYP3A (most likely CYP3A1) after treatment of rats with EcN was found. CONCLUSION: This in vivo study revealed that the levels of colon CYP3A could be significantly increased in rats treated with probiotic EcN. On the contrary, the expression of CYP3A in the duodenum decreased. However, the changes in the expression of CYP enzymes are probably not as extensive to be clinically important in man; hence, most likely the probiotic EcN has little influence on the intestinal drug metabolism by CYP enzymes.

Polysubstituted Pyrimidines as mPGES-1 Inhibitors: Discovery of Potent Inhibitors of PGE2 Production with Strong Anti-inflammatory Effects in Carrageenan-Induced Rat Paw Edema.

We report an extensive structure-activity relationship optimization of polysubstituted pyrimidines that led to the discovery of 5-butyl-4-(4-benzyloxyphenyl)-6-phenylpyrimidin-2-amine, and its difluorinated analogue. These compounds are sub-micromolar inhibitors of PGE2 production (IC50 as low as 12 nM). In order to identify the molecular target of anti-inflammatory pyrimidines, we performed extensive studies including enzymatic assays, homology modeling and docking. The difluorinated analogue simultaneously inhibits two key enzymes of the arachidonic acid cascade, namely mPGES-1 and COX-2, with mPGES-1 inhibition being the principal mechanism of action. Other pyrimidines studied are potent mPGES-1 inhibitors with no observed inhibition of COX-1/2 enzymes. Moreover, the two most potent compounds proved to be significantly effective in vivo in a model of acute inflammation, suppressing carrageenan-induced rat paw edema by 36 and 46 %. The promising results of this study warrant further preclinical evaluation of selected anti-inflammatory candidates.

Resveratrol attenuates lipopolysaccharide-induced hepatitis in D-galactosamine sensitized rats: role of nitric oxide synthase 2 and heme oxygenase-1.

The goal of study was directed to investigate the effects of resveratrol (RES) pretreatment on the enhancing action of D-galactosamine (D-GalN; 800 mg/kg) on lipopolysaccharide (LPS; 0.5 microg/kg) inducing liver failure in rats. Liver function was assessed by determination of plasma alanine aminotransferase (ALT), aspartate aminotransferase (AST), alpha-glutathione S-transferase (alpha GST) and bilirubin (BILI). Plasma NO(2)(-) was assessed by NO(2)(-)/NO(3)(-) colorimetric kit. The estimation of nonenzymatic and enzymatic antioxidants (glutathione and catalase) was performed in plasma and liver homogenate. Lipid peroxidation was evaluated by the thiobarbituric acid reacting substances (TBARS) and the conjugated dienes (CD). Morphological examinations using light and electron microscopy were performed. Observations related to pharmacological increases of inducible nitric oxide synthase (NOS-2)/nitric oxide (NO) and inducible heme oxygenase (HO-1) in fulminant hepatic failure and modulation by resveratrol were followed up by real-time reverse transcription PCR (RT-PCR) in liver tissue. In the present study we found that among the mechanisms responsible for the hepatoprotective effect of resveratrol in the LPS/D-GalN liver toxicity model are reduction in NO, downregulation of NOS-2, modification of oxidative stress parameters and modulation of HO-1 which led to overall improvement in hepatotoxic markers and morphology after the hepatic insult.

Effects of resveratrol pretreatment on tert-butylhydroperoxide induced hepatocyte toxicity in immobilized perifused hepatocytes: involvement of inducible nitric oxide synthase and hemoxygenase-1.

The aim of this work was to study the effects of resveratrol (RES) as compared to silymarin (SM) pretreatments on tert-butylhydroperoxide (tBH) induced apoptotic/necrotic markers in hepatocytes. Hepatocyte in cultures (48 h) and in perifused immobilized agarose threads (5h) were used as cellular systems. Hepatocyte apoptosis was estimated morphologically using Annexin-V combined with propidium iodide, or toluidine blue staining. Hepatocyte viability and functionality were evaluated by ALT and urea synthesis. Nitric oxide (NO) and carbon monoxide involvements were also examined. Resveratrol and silymarin reduced tBH-induced hepatocyte toxic effects in short term experiments (5h) as measured by a significant reduction in ALT and NO increase produced by tBH. Both inducible nitric oxide synthase (NOS-2) and hemoxygenase-1 (HO-1) gene expression were increased by tBH and reduced by both RES and SM pretreatments. Morphologically, there were ameliorations in both apoptotic and necrotic markers under RES treatment and were similar to biochemical findings. In addition, RES improved hepatocyte stability in both cellular systems. It may be concluded that resveratrol and sylimarin ameliorative effects on tBH hepatocyte toxicity are comparable; involve NOS-2 and HO-1 expression and should be re-evaluated in various in vitro and in vivo experimental conditions.

Influence of probiotics on rat liver biotransformation enzymes.

OBJECTIVES: The aim of the study was to find, whether probiotic Escherichia coli Nissle 1917 O6:K5:H1 (EcN) influence the amount and activity of cytochromes P450 (CYP) in rat liver. DESIGN: Live bacterial suspension of EcN was applied to the female Wistar rats in single dose or for 14 days consecutively. The bacterial lipopolysaccharide (LPS) isolated by phenol extraction from the EcN was given to the rats for 14 days as well. Control rats were treated with the saline solution daily for 14 days. Relative amount of CYP2C6, CYP2C9 (corresponding to rat CYP2C11), CYP3A1 and CYP1A2 protein expression in rat liver microsomes was determined by Western blotting. For the determination of six CYP activities (corresponding to human CYP1A2, CYP2A6, CYP2B6, CYP3A4, CYP2C9 and CYP2D6) fluorescence, luminescence or absorbance detection was used. RESULTS: The data presented show that the changes of the total content of the CYP enzymes in rat liver are not significant after administration of the probiotic for 1 or 14 days as well as of the LPS. Western blots revealed a slight increase in CYP2C6 protein expression; level of another rat CYP2C protein (readings with anti-human CYP2C9 antibody corresponding to the rat CYP2C11) as well as of CYP1A2 was elevated after administration of LPS; a small decrease was observed with CYP3A1 protein. Changes in activities of CYP forms are not significant, only the activity of rat CYP2C forms in liver microsomal samples of rats given free LPS appeared to exhibit a small, but significant tendency to increase. CONCLUSION: The results show that the p.o. administration of probiotics to rat does not markedly influence the rat hepatic CYP enzymes.