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Biomedical subjects

S Laufer

Publications and source records attributed to S Laufer.

At least 19 recordsLinked to original sources
PubMed2006

Antioxidative properties of the gastrointestinal phytopharmaceutical remedy STW 5 (Iberogast).

Since inflammation is a common mechanism of many gastrointestinal diseases, reactive oxygen metabolites may play an important role in their pathophysiology. Therefore it is interesting to know, whether phytopharmaceuticals known to modulate gastrointestinal motor function reveal also antioxidative properties. We tested STW 5 (Iberogast), its constituent nine different plant extracts, and some isolated compounds which are present in STW 5 for characterizing their antioxidative and radical quenching activities. The test assays consisted in pure chemical and complex cellular systems in which different types of reactive species were produced. Quantification of the effects was based on chemiluminescence reactions. The results show that all extracts contribute to the effect of the complete remedy STW 5, in the chemical systems in a strongly additive manner, in the cellular systems in a supraadditive manner. The largest contributions resulted from the extracts from peppermint and melissa leaves. Comparison of effects from isolated phytochemical compounds from the extracts with that of the extracts itself shows that usually the extract is more effective than the monosubstance which indicates also the synergism within the whole plant extracts. This means that the plant extracts present in STW 5 provide strong radical quenching activities that could also be involved in the therapeutic gastrointestinal actions.

Free Radical Scavengers↗
PubMed2006

The effect of single-dose naproxen on eicosanoid formation in human gastroduodenal mucosa.

BACKGROUND: In animal studies, aspirin and non-aspirin non-steroidal anti-inflammatory drugs contribute to gastroduodenal damage via cyclo-oxygenase inhibition and consecutive leucotriene formation (COX-LOX eicosanoid shunt). AIM AND METHODS: Ten Helicobacter pylori-negative healthy volunteers received a single dose of 500 mg naproxen to address two questions: (i) is there a crosstalk between eicosanoids before medication in the human gastroduodenal mucosa and (ii) can we demonstrate a COX-LOX shunt following single-dose naproxen? RESULTS: Significant correlations in the stomach mucosa before medication were obtained between leucotriene B4 (LTB4) and thromboxane B(2) (TxB(2); r = -0.38, P = 0.05), as well as LTB4 and prostaglandin E(2) (PGE(2); r = 0.71, P < 0.0001). In serum, a >90% inhibition of TxB(2) and PGE(2) occurred within 30 min of naproxen administration. In gastric mucosa, a significant decrease of TxB(2) occurred already at 15 min and preferably in the antrum. For LTB4 there was a non-significant trend towards a transient increase. Mucosal PGE(2) was unchanged in all regions; transcript levels of both cyclo-oxygenases/5-lipoxygenase were unaffected (except for a trend of increasing cyclo-oxygenase-2 in the corpus). CONCLUSIONS: Baseline correlations between LTB4-TxB(2) and LTB4-PGE(2) reflect a crosstalk between these eicosanoids. A COX-LOX shunt; however, cannot be demonstrated following single-dose naproxen in a low-risk population.

Adult↗
PubMed2005

Licofelone, a novel 5-LOX/COX-inhibitor, attenuates leukocyte rolling and adhesion on endothelium under flow.

The main mechanism of action of non-steroidal anti-inflammatory drugs (NSAIDs) is the inhibition of cycloxygenases COX-1 and COX-2. During recent years, combined 5-LOX/COX-inhibition, interfering with the biosynthesis of both prostaglandins and leukotrienes (LTs), has emerged as a possibility to avoid side effects related to COX-inhibition. The aim of the present study was to investigate if there is a contribution of mechanisms other than the reduction of inflammatory prostaglandins and leukotrienes to the anti-inflammatory effect of the LOX/COX inhibitor licofelone. In a flow chamber assay, licofelone (10-30 microM) dose-dependently decreased both the rolling and adhesion of leukocytes on endothelial cells (EC). In contrast, no effects were found after treatment of EC with the unselective COX-1/COX-2 inhibitor indomethacin (30 microM), the potent and selective 5-LOX inhibitor, ZD-2138 (30 microM), the mainly COX-2 inhibitor aceclofenac (30 microM), the selective COX-2 inhibitor celecoxib (30 microM) and the combination of ZD-2138 with the selective COX-2 inhibitor celecoxib (30 microM). In the presence of licofelone (30 microM) the expression of E-selectin mRNA in cytokine-stimulated EC was attenuated, whereas no NSAID (30 microM) tested showed any effect on E-selectin expression. Moreover, licofelone treatment (30 microM) attenuated expression of VCAM-1 and ICAM-1 on inflammatory EC. The effect of licofelone on leukocyte recruitment was also evaluated in vivo. Using a mouse peritonitis model it was found that leukocyte accumulation was markedly reduced in licofelone treated animals (100mg/kg) compared to untreated mice. Thus, the novel 5-LOX/COX inhibitor licofelone possesses anti-inflammatory activity that, in addition to COX/LOX inhibition, involves effects on leukocyte-endothelial interactions.

Acetates↗
PubMed2005

PGE(2) in the regulation of programmed erythrocyte death.

Hyperosmotic shock, energy depletion, or removal of extracellular Cl(-) activates Ca(2+)-permeable cation channels in erythrocyte membranes. Subsequent Ca(2+) entry induces erythrocyte shrinkage and exposure of phosphatidylserine (PS) at the erythrocyte surface. PS-exposing cells are engulfed by macrophages. The present study explored the signalling involved. Hyperosmotic shock and Cl(-) removal triggered the release of prostaglandin E(2) (PGE(2)). In whole-cell recording, activation of the cation channels by Cl(-) removal was abolished by the cyclooxygenase inhibitor diclophenac. In FACS analysis, phospholipase-A(2) inhibitors quinacrine and palmitoyltrifluoromethyl-ketone, and cyclooxygenase inhibitors acetylsalicylic acid and diclophenac, blunted the increase of PS exposure following Cl(-) removal. PGE(2) (but not thromboxane) induced cation channel activation, increase in cytosolic Ca(2+) concentration, cell shrinkage, PS exposure, calpain activation, and ankyrin-R degradation. The latter was attenuated by calpain inhibitors-I/II, while PGE(2)-induced PS exposure was not. In conclusion, hyperosmotic shock or Cl(-) removal stimulates erythrocyte PS exposure through PGE(2) formation and subsequent activation of Ca(2+)-permeable cation channels.

Ankyrins↗
PubMed2004

The regulation of human MMP-13 by licofelone, an inhibitor of cyclo-oxygenases and 5-lipoxygenase, in human osteoarthritic chondrocytes is mediated by the inhibition of the p38 MAP kinase signalling pathway.

BACKGROUND: MMP-13 is one of the most important metalloproteases (MMP) involved in osteoarthritis. Licofelone, a novel dual inhibitor of cyclo-oxygenases (COX) and 5-lipoxygenase (5-LOX), can modulate MMP-13 production in human osteoarthritis chondrocytes. OBJECTIVE: To evaluate the impact of licofelone on MMP-13 expression/production, promoter, and major MAP kinase signalling pathways and transcription factors. METHODS: Human osteoarthritis chondrocytes were stimulated by interleukin 1beta (IL1beta) and treated with or without: licofelone (0.3, 1, or 3 mug/ml); NS-398 (10 muM; a specific COX-2 inhibitor); or BayX-1005 (10 muM; a specific 5-LOX inhibitor). MMP-13 synthesis was determined by specific enzyme linked immunosorbent assay, and expression by real time polymerase chain reaction. The effect of licofelone on the MMP-13 promoter was studied through transient transfection; dexamethasone (10(-7) M) was used as comparison. The effect on IL1beta induced MMP-13 signalling pathways was determined using specific ELISA for phosphorylated MAP kinases and transcription factors. RESULTS: Licofelone dose dependently inhibited the IL1beta stimulated production and expression of MMP-13. NS-398 and BayX-1005 had very little effect. Licofelone also inhibited MMP-13 transcription on each of the promoter constructs used. The licofelone inhibition was comparable to that obtained with dexamethasone. Licofelone had no effect on phosphorylated p44/42 or JNK1/2; however, it decreased phosphorylated c-jun and inhibited phosphorylated p38, CREB, and AP-1 activity. CONCLUSIONS: Licofelone inhibited MMP-13 production under proinflammatory conditions on human osteoarthritis chondrocytes, through inhibition of the p38/AP-1 pathway and the transcription factor CREB. This may explain some of the mechanisms whereby licofelone exerts its positive effect on osteoarthritic changes.

Acetates↗
PubMed2004

Osteoarthritis therapy--are there still unmet needs?

Non-steroidal anti-inflammatory drugs (NSAIDs) and selective cyclooxygenase (COX)-2 inhibitors are commonly used to control pain and inflammation in osteoarthritis. However, these agents have been associated with gastrointestinal, renal and cardiovascular adverse effects. Together, these complications indicate a clear unmet need in the safety of current treatment options for the management of osteoarthritis. NSAIDs are known to have adverse gastrointestinal effects, and more recently it has been suggested that some selective COX-2 inhibitors are also associated with serious gastrointestinal complications. Selective COX-2 inhibitors have a similar capacity to NSAIDs to delay ulcer healing, and may not significantly decrease the incidences of perforation, ulceration and bleeding (the most clinically relevant gastrointestinal endpoints) compared with NSAIDs. These effects may be due to overlapping roles of COX-1 and COX-2 in physiological and pathophysiological processes. Furthermore, as COX-2 is integrally involved in renal homeostasis, selective COX-2 inhibitors are associated with negative effects on kidney function similar to those seen with NSAIDs. Electrolyte disturbances, oedema and hypertension have been correlated with the use of both drug classes. Additionally, selective COX-2 inhibitors have the potential to increase cardiovascular events, although further research is required to clearly determine such a risk. With the current unmet needs in the treatment of osteoarthritis, the opportunity exists for the development of new therapies. Novel agents include the COX-inhibiting nitric oxide donors and the lipoxygenase (LOX)/COX inhibitor licofelone. Initial results suggest that these therapies may have tolerability advantages over the NSAIDs and selective COX-2 inhibitors.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2004

Treatment with licofelone prevents abnormal subchondral bone cell metabolism in experimental dog osteoarthritis.

OBJECTIVES: To determine if treatment with licofelone, a combined 5-lipoxygenase and cyclo-oxygenase inhibitor, in vivo in experimental dog osteoarthritis can modify bone cell metabolism in long term in vitro subchondral osteoblast cell cultures (Ob). METHODS: Group 1 received sectioning of the anterior cruciate ligament (ACL) of the right knee with no active treatment (placebo group). Groups 2 and 3 received sectioning of the ACL of the right knee, and were given licofelone (2.5 or 5.0 mg/kg daily by mouth, respectively) for eight weeks beginning the day after surgery. Primary Ob were prepared from the subchondral bone plate. Levels of phenotypic markers (alkaline phosphatase activity, osteocalcin release), and urokinase plasminogen activator (uPA) and insulin-like growth factor-1 (IGF-I) levels, were evaluated in each group. Lastly, prostaglandin E(2) (PGE(2)) and leucotriene B(4) levels were evaluated. RESULTS: No significant differences in alkaline phosphatase activity or osteocalcin release from Ob between the three groups, under either basal or 1,25(OH)(2)D(3) induction were seen. In contrast, treatment with licofelone reduced uPA and IGF-I levels in Ob. PGE(2) levels, which were still raised in the placebo group, were decreased sharply by licofelone. A relationship was found between licofelone treatment and either the reduction in the size of lesions on tibial plateaus or the levels of uPA, IGF-I, or PGE(2). CONCLUSIONS: Licofelone treatment prevents and/or delays the abnormal metabolism of subchondral osteoblasts in this model. Licofelone reduced PGE(2) levels after long term Ob, suggesting that the reduction in uPA and IGF-I levels is linked, at least in part, to this reduction.

Acetates↗
PubMed2002

Antithrombotic and platelet function inhibiting effects of ML3000, a new antiinflammatory drug with Cox/5-LOX inhibitory activity.

DESIGN: The studies reported were designed to evaluate the effects of ML3000 on platelet aggregation and platelet-induced thrombin generation in human platelet rich plasma and its antithrombotic effect in a rat thrombosis model. ML3000 is a potent inhibitor of both COX-1/2 and 5-LOX with demonstrated antiinflammatory activity and a low incidence of GI mucosal injury in animal and human studies. METHODS AND RESULTS: The antithrombotic activity of ML3000 (10, 30 and 100 mg/kg) and aspirin (30 and 100 mg/kg) was measured in the mesenteric venules of rats using the laser-induced thrombus model. Both ML3000 and aspirin, at all doses tested, showed significant antithrombotic activity. The mean number of laser injuries necessary to induce a thrombus that blocked the vessel was 1.93 +/- 0.28 in the control group, 3.3 +/- 0.53, 3.6 +/- 0.14 or 4.07 +/- 0.37 in the groups treated with ML3000 at 10, 30 or 100 mg/kg p.o. and 3.4 +/- 0.55 or 3.9 +/- 0.3 in the groups treated with Aspirin at 30 or 100 mg/kg p.o. The antithrombotic activity in this model was significant up to 12 h post-administration of 100 mg/kg ML3000 or Aspirin. The aggregation inhibiting activity of ML3000 (1-100 microg/ml) and indomethacin (1 microg/ml) was studied using the following inducing agents: ADP (1 and 2 microM), epinephrine (25 and 50 microM), collagen (0.5 and 1 microg/ml), and the thromboxane mimetic U46619 (0.8 and 1.6 microM). Aggregation inhibitory activity was observed with ML3000 in all assays except with the higher concentration of U46619 at 1.6 microM. Indomethacin (1 microg/ml) inhibited aggregation in all assays. CONCLUSIONS: ML3000 has significant antithrombotic activity and a marked platelet aggregation inhibiting effect. Given its demonstrated antiinflammatory activity, platelet function inhibition, and antithrombotic effects along with a lack of effect on the GI mucosa, ML3000 may offer an alternative to the combination of a COX-2 inhibitor and aspirin in arthritis patients at risk for cardiovascular disease.

Acetates↗
PubMed2002

The mechanism of action of the new antiinflammatory compound ML3000: inhibition of 5-LOX and COX-1/2.

OBJECTIVE: We examined the effects of ML3000 and several non-steroidal antiinflammatory drugs (NSAIDs) on the synthesis of products of 5-LOX (LTB4, LTC4) and COX-1/2 (TXB2, PGE2) in vitro and ex vivo in order to further elucidate the mechanism of action of ML3000. METHODS AND RESULTS: Using a human whole blood assay the effect of ML3000 on the shunt of arachidonic acid to the lipoxygenase pathway when COX is blocked was studied. ML3000 (0.3, 1, 3, 10, 30 microg/ml) and indomethacin (0.3, 1, 3, 10, 30 microg/ml) concentration-dependently inhibited the synthesis of PGE2 (IC50 = 3.9 and 4.5 microM). In contrast to ML3000, indomethacin produced an increase of LTC4 of up to 155.5% of control. 5-lipoxygenase inhibition was further tested in a basophilic leukemia cell assay using RBL-1 cells. ML3000 (1-10 microM) inhibited the synthesis of LTB4 in a concentration related manner (IC50: 3.6 microM). In carrageenan induced rat paw edema, ML3000 and indomethacin completely blocked the formation of PGE2 in the inflamed tissue. The LTB4 production in the inflamed paw was reduced to basal levels by ML3000 (10 +/- 1.4 pg/paw saline control and 7.5 +/- 1.3-5.9 +/- 3.2 pg/paw ML3000), whereas LTB4 levels remained markedly elevated as compared to saline control by indomethacin (30.7 pg/paw). 5-LOX inhibition in the inflamed rat colon was investigated by measuring LTB4 synthesis. MK-886 and ML3000 at 10 mg/kg p.o. reduced LTB4 production to 29.8 +/- 4.9 and 30.1 +/- 2.8 pg/mg tissue as compared to control (54.2 +/- 7.4 mg/kg tissue). LTB4 levels in the rat stomach were comparable to control (2.5 +/- 0.4 pg/mg protein) after oral administration of ML3000 (10, 30, 100 mg/kg), whereas oral treatment with indomethacin (0.3, 1, 3 mg/kg) or diclofenac (1, 3 mg/kg) increased LTB4 up to 9.2 +/- 2.3 or 8.9 +/- 1.6 pg/mg protein. This effect was significant at 1 mg/kg diclofenac and 0.3 mg/kg indomethacin. CONCLUSIONS: These results provide further evidence, that ML3000 inhibits 5-LOX as well as COX-1 and COX-2 in vitro and in animal experiments. The favourable gastrointestinal (GI) tolerability of the compound is believed to be linked to the mechanism of combined 5-LOX and COX-1/2 inhibition of ML3000.

Acetates↗
PubMed2002

An in-vitro screening assay for the detection of inhibitors of proinflammatory cytokine synthesis: a useful tool for the development of new antiarthritic and disease modifying drugs.

OBJECTIVE: This work targets the development of a new tool to help develop new anticytokine drugs that prevent or reduce the progression of arthritic diseases. The specific aim of our study was to establish a fast and reliable in vitro screening assay of cytokine synthesis inhibitors (TNFalpha, IL-1beta) which shows better correlation with enzyme assays than previously reported in vitro assays. The test system should be able to detect p38-MAP kinase inhibitors. MATERIAL AND METHODS: Human peripheral blood mononuclear cells (PBMCs) were isolated by Ficoll density gradient centrifugation from human EDTA-potassium whole blood. Cells were adjusted at 1 x 10(6) cells/ml. PBMCs were stimulated with lipopolysaccharide (LPS; E. coli serotype 026:B6: 1 microg/ml) in the presence of test compound (10(-5)-10(-8)M) for 4h at 37 degrees C in a 5% CO(2)-incubator. Induced TNFalpha and IL-1beta protein were measured by ELISA. RESULTS: The following are representative examples of inhibitors which effect cytokine synthesis. Corticoid Dexamethasone inhibits IL-1beta and TNFalpha synthesis at IC(50) of 38 nM and 25 nM, respectively. ERK1/ERK2 inhibitor U0126 effects cytokine synthesis at IC(50) of 0.34 microM for IL-1beta production and 0.26 microM for TNFalpha synthesis.p38-MAP kinase inhibitor SB 203580 inhibits IL-1beta- and TNF-alpha-synthesis (IC(50)sof 0.052 microM and 0.46 microM) in the same degree as p38-MAP kinase activity (IC(50): 0.34 microM). Same results could be shown for SB 210313, which had same efficacy on IL-1beta and TNFalpha biosynthesis (IC(50)'s: 1.88 microM and 1.01 microM) and on p38-MAP kinase (IC(50): 6.85 microM). Also for SB 202190 this correlation in inhibition of IL-1beta and TNFalpha synthesis (IC(50)'s: 0.055 microM and 1.01 microM) and p38-MAP kinase inhibition (IC(50): 0.088 microM) could be shown. CONCLUSION: This study shows the screening assay using PBMCs stimulated with LPS for IL-1beta and TNFalpha synthesis is a reliable test system for the quantification of the effectiveness of new drugs modulating IL-1beta and TNFalpha synthesis which is mainly mediated by p38-MAP Kinase. These assay allows fast detection of IL-1beta and TNFalpha synthesis inhibitors with different modes of action, including p38-MAP kinase inhibitors. The results obtained with our in-vitro screening assay show good correlation with results from enzyme assays.

Blotting, Western↗
PubMed2001

Synthesis and cyclooxygenase inhibitory properties of novel (+) 2-(6-methoxy-2-naphthyl)propanoic acid (naproxene) derivatives.

Halomethylation of naproxene (1) occurs regioselectively in position 5 and subsequently--in situ or on treatment with silver nitrate--leads to naproxene-"dimers" with two naproxene units, 5,5'-connected through a ethenylene (3) and a methylene (4) bridge, respectively. Two of the new naproxene derivatives were screened for their cyclooxygenase inhibitory properties relative to naproxene. Both 5-chloromethyl naproxene (2) and 2-(5-((carboxyethyl)-2-methyloxynaphthyl)-6-methoxy-2-naphthyl)propanoic acid (4) were inactive in the concentration range of 0.1-10 mumole against both COX-1 and COX-2, indicating that bulky substituents in position 5 in naproxene are unfavourable for both COX-1 and COX-2 inhibition.

Cyclooxygenase 1↗
PubMed2001

In vivo dual inhibition of cyclooxygenase and lipoxygenase by ML-3000 reduces the progression of experimental osteoarthritis: suppression of collagenase 1 and interleukin-1beta synthesis.

OBJECTIVE: To study the therapeutic effectiveness of ML-3000, a new antiinflammatory drug that has balanced dual inhibitory activity against 5-lipoxygenase and cyclooxygenase, on the development of lesions in the experimental osteoarthritis (OA) dog model, and to determine the action of ML-3000 on the synthesis of collagenase 1 in cartilage and interleukin-1beta (IL-1beta) in synovial membrane. METHODS: The anterior cruciate ligament of the right stifle joint of 21 mongrel dogs was sectioned with a stab wound. Dogs were divided into 3 groups: group 1 (n = 7) received placebo; groups 2 (n = 7) and 3 (n = 7) were treated with therapeutic dosages of oral ML-3000 at 2.5 mg/kg/day and 5 mg/kg/day, respectively. The dogs began receiving medication the day after surgery and were killed 8 weeks later. The size and grade of cartilage erosions on both the condyles and plateaus were evaluated, and the severity of the cartilage lesions and synovial inflammation was examined histologically. Levels of collagenase 1 in cartilage and IL-1beta in the synovial membrane were measured by immunohistochemistry. In addition, levels of prostaglandin E2 (PGE2) in the synovial fluid and leukotriene B4 (LTB4) in cultured synovial membrane explants were determined using specific enzyme immunoassays. RESULTS: Serum levels of ML-3000 in treated dogs were within the therapeutic range. ML-3000 significantly decreased the size and grade of the cartilage lesions in tibials and plateaus, compared with placebo. At the histologic level, the severity of cartilage lesions was also decreased in the ML-3000-treated dogs versus the placebo-treated dogs in both the condyles and the plateaus. All 3 OA groups exhibited a notable and similar level of synovial inflammation. ML-3000 significantly decreased the level of PGE2 in synovial fluid and LTB4 production by synovium. It also markedly reduced the levels of collagenase 1 in cartilage and IL-1beta in synovial membrane. CONCLUSION: ML-3000 significantly reduced the development of lesions in experimental dog OA. The drug acts by reducing the synthesis of the inflammation mediators PGE2 and LTB4 and catabolic factors such as collagenase 1 and IL-1beta, which are known to play an important role in the pathophysiology of OA lesions. The effect of the drug on catabolic factors could possibly be related to its inhibitory action on LTB4 synthesis.

Acetates↗
PubMed2001

Anti-inflammatory drugs: new multitarget compounds to face an old problem. The dual inhibition concept.

In this short review we have tried to focus on some new relevant aspects of the pharmacological control of inflammation. The clinical availability of new drugs able to produce a selective inhibition of type 2 cyclooxygenase (COX-2), the enzyme thought to be mainly responsible for generating arachidonic-acid-derived inflammatory mediators, has been the origin of much hope. However, expectations of having an effective and completely safe non-steroidal anti-inflammatory drug (NSAID) have been only partially fulfilled. Emerging information has challenged some aspects of the original hypothesis indicating COX-2 as devoid of 'housekeeping' physiological functions. Moreover, the recently available clinical studies have indicated only a relatively small improvement in the tolerability of the newer 'selective' COX-2 inhibitors over the classical COX-1/COX-2 mixed type NSAIDs. The new appreciation of the role of other arachidonic acid derivatives, the leukotrienes (LTS), in producing and maintaining inflammation has generated considerable interest in drugs able to block LTS receptors or to produce a selective inhibition of 5-lipoxygenase (5-LO), the initial key enzyme of the leukotriene pathway. These drugs are now included among the effective therapies of asthma but appear, in the few clinical studies performed, to be an insufficient single therapeutic approach in other inflammatory diseases. Drugs able to block equally well both COX and 5-LO metabolic pathways (dual inhibitors) have been developed and experimentally evaluated in the last few years, but none are available on the market yet. The pharmacological rationale at the basis of their development is strong, and animal studies are indicative of a wide range of anti-inflammatory activity. What appears most impressive from the available studies on dual inhibitors is their almost complete lack of gastric toxicity, the most troublesome side effect of NSAIDs. The mechanism of the gastric-sparing properties of these drugs is not yet completely understood; however, it appears that leukotrienes significantly contribute to gastric epithelial injury particularly when these compounds represent the major arachidonic acid derivatives present in the gastric mucosa after inhibiton of prostanoid production.

Animals↗
PubMed2001

Dual inhibition of 5-lipoxygenase and cyclooxygenases 1 and 2 by ML3000 reduces joint destruction in adjuvant arthritis.

OBJECTIVE: To search for potential new therapies to inhibit the progression of joint destruction in patients with rheumatoid arthritis. METHODS: We evaluated the dual acting antiinflammatory drug ML3000 (2,2-dimethyl-6-(4-chlorophenyl)-7-phenyl-2,3-dihydro- H-pyrrolizine-5-yl) acetic acid, a dual inhibitor of 5-lipoxygenase (5-LOX) as well as both cyclooxygenases (COX-1 and COX-2) in the rat model of adjuvant arthritis. On Day 0, female Lewis rats (5 per group) were injected intradermally with complete Freund's adjuvant at base of the tail. Treatment began on Day 2; the rats received ML3000 (20 or 80 mg/kg/day) twice daily 7 h apart for 28 days and were then sacrificed. To reduce pain, the positive control group and 2 treatment groups received paracetamol (3 mg/ml water). Joint histology was scored for synovial cell proliferation, fibroproliferative pannus, and cartilage and bone erosions, as well as diffuse leukocyte infiltrates. RESULTS: Daily doses of 20 or 80 mg/kg ML3000 significantly reduced the arthritis associated deficiency of body growth, the edema/erythema score, and splenomegaly. In the ankle joint, ML3000 significantly reduced the overall histological score, synovial cell proliferation, and bone/cartilage erosions, and inhibited the appearance of fibroproliferative pannus. The addition of paracetamol in the drinking water had no influence. No side effects were noted. CONCLUSION: ML3000 is an antiarthritic drug with a high gastrointestinal tolerability, which can reduce synovial cell proliferation and joint erosion and is capable of markedly suppressing prostaglandin synthesis.

Acetates↗
PubMed2000

Structural approaches to explain the selectivity of COX-2 inhibitors: is there a common pharmacophore?

The identification and characterisation of the isoenzyme cyclooxygenase 2 (COX-2) stimulated investigations to develop efficient non-steroidal anti-inflammatory drugs with reduced side effects compared to standard NSAIDs. This review will focus on the structural features needed to achieve COX-2 selectivity. Five structural classes can be identified together with a class bearing little or no resemblance to one another in their molecular structure. The most interesting point is the very distinct structure/activity relationship. On the one hand only minor modifications to a particular compound induce a drastic change in its COX selectivity and on the other hand the structural prerequisites in terms of molecular shape, lipophilicity, electron density, flexibility, polarity and H-bonding dynamics allow a wide range of diversity.

Animals↗
PubMed1999

Development of an in-vitro test system for the evaluation of cyclooxygenase-2 inhibitors.

OBJECTIVE AND DESIGN: The aim of our study was to establish an in-vitro test system, capable of fast and efficient screening of Cyclooxygenase-2 (COX-2) inhibitors. MATERIALS: Mononuclear cells were isolated out of human whole blood, in a one-step centrifugation procedure. TREATMENT AND METHODS: The time- and concentration-dependent induction of COX-2 expression in the blood monocytes (1 x 10(6) cells/ml) was evaluated by a kinetic profile. The optimal test conditions were fixed at an LPS concentration of 10 micrograms/ml and a 5 hour incubation time. The test compounds (10(-5) to 10(-8) mol/l) were set at t = 0 into the assay and were co-incubated for the whole period of COX-2 expression (5 hr). RESULTS: The following are representative examples of inhibitors with different distinct selectivity for COX-1/2. Indomethacin as a COX-1 selective compound inhibited PGHS-1 (IC50: 0.002 microM) 200 times stronger than PGHS-2 (IC50: 0.43 microM). Diclofenac had an almost equipotent efficacy on PGHS-1 (IC50: 0.05 microM) and PGHS-2 (IC50: 0.03 microM). NS-398 inhibited highly selective COX-2 (IC50 PGHS-1: 10.75 microM vs IC50 PGHS-2: 0.16 microM). CONCLUSIONS: The model reached the set targets with regard to the differentiation of COX-2 selective compounds, the reproducibility of results and practicability of the assay. In contrast to previous propounded theories, we could demonstrate, that mononuclear cells are not unusually sensitive to NSAIDs and apparently possess no further COX isoforms.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1998

Anti-inflammatory activity of myricetin-3-O-beta-D-glucuronide and related compounds.

OBJECTIVE AND DESIGN: The anti-inflammatory effect of myricetinglucuronide (MGL) was investigated and structurally-related compounds were compared to examine the structure/activity-relationship in carrageenan-induced rat paw edema. MATERIALS AND SUBJECTS: In vitro studies were performed using rat basophilic leukemia (RBL-1) cells, human polymorphonuclear leukocytes (PMNL), COX-1 from ram seminal vesicle, COX-2 from sheep placenta and human venous blood. For the in vivo tests male Wistar rats were used, for the ex vivo test perfused rabbit ears. TREATMENT: 1-300 microg/kg MGL or myricetinmethylglucuronate and 0.1-5 mg/kg other related compounds administered p.o. (carrageenan edema). 5, 50 and 150 microg/kg MGL p.o. for 14 days (Freund's adjuvant arthritis), 5 and 50 microg/kg p.o. for 6 days (ulceration). METHODS: Anti-inflammatory effects were measured in carrageenan edema and in adjuvant arthritis. Incidence of gastric lesions was tested in an ulcerogenicity model in vivo. Influence on COX was determined in the perfused rabbit ear, in PMNL and in a test assay using COX-1 and COX-2. 5-LOX activity was studied using PMNL and RBL-1. The influence on platelet aggregation was evaluated measuring light transmission. RESULTS: MGL exerted a marked and dose-dependent anti-inflammatory effect in acute (carrageenan edema, ED50 15 microg/kg, indomethacin ED50 10 mg/kg) and chronic (adjuvant arthritis, inhibition at 150 microg/kg 18.1 % left paw, 20.6% right paw, indomethacin 3 mg/kg 18.0% and 19.4%)) models of inflammation. In the perfused rabbit ear 1 microg MGL inhibited the release of PGI2, PGD2 and PGE2 to the same extent as 1 microg indomethacin. The inhibition of COX-1 in the intact cell system was IC50 = 0.5 microM, that of indomethacin 0.0038 microM. In the isolated enzyme preparations of COX-1 and COX-2 the IC50 was 10 microM and 8 microM, that of indomethacin 9.2 mM and 2.4 microM. In the RBL-1 and PMNL test assay the inhibition of 5-LOX was 0.1 microM and 2.2 microM. An orally administered dose of 50 microg/kg/day induced no gastric ulcers in rats treated for 6 days. The investigations on carrageenan edema showed a close relationship between the structure of MGL and the anti-inflammatory effect. CONCLUSIONS: MGL is a COX-1, COX-2 and 5-LOX inhibitor. In view of the moderate in vitro activity and the very potent in vivo activity an additive mechanism must be involved. Small changes in the molecular structure lead to the loss or reduction of the anti-inflammatory activity.

Animals↗