Inhibitory activity of tryptanthrin on prostaglandin and leukotriene synthesis

The indolo[2,1- b]quinazoline alkaloid tryptanthrin has previously been identified as the cyclooxygenase-2 (COX-2) inhibitory principle in the extract ZE550 prepared from the medicinal plant Isatis tinctoria (Brassicaceae). We here investigated the potential inhibitory activity of tryptanthrin and ZE550 on COX-2, COX-1 in cellular and cell-free systems. A certain degree of selectivity towards COX-2 was observed when COX-1-dependent formation of thromboxane B(2) (TxB(2)) in HEL cells and COX-2-dependent formation of 6-ketoprostaglandin F(1alpha) (6-keto-PGF(1alpha)) in Mono Mac 6 and RAW 264.7 cells were compared. Preferential inhibition of COX-2 by two orders of magnitude was found in phorbol myristate acetate (PMA) activated bovine aortic coronary endothelial cells (BAECs). Assays with purified COX isoenzymes from sheep confirmed the high selectivity towards COX-2. The leukotriene B(4) (LTB(4)) release from calcium ionophore-stimulated human granulocytes (neutrophils) was used as a model to determine 5-lipoxygenase (5-LOX) activity. Tryptanthrin and the extract ZE550 inhibited LTB(4) release in a dose dependent manner and with a potency comparable to that of the clinically used 5-LOX inhibitor zileuton.     

Anti-inflammatory and antiallergic activity in vivo of lipophilic Isatis tinctoria extracts and tryptanthrin

The effects of a supercritical CO2 (SFE) extract, a dichloromethane (DCM) extract from Isatis tinctoria leaf and the alkaloidal constituent tryptanthrin were studied in acute and subchronic experimental models of inflammation. The SFE and DCM extracts showed anti-inflammatory activity in the carrageenan-induced acute mouse paw oedema (ED50 values of 78 mg/kg and 165 mg/kg P. O., respectively) and in the acute tetradecanoylphorbol acetate (TPA)-induced mouse ear oedema in oral (62% and 32% oedema reduction at 100 and 125 mg/kg, respectively) and topical application (37% and 33% reduction of oedema at 0.5 mg/ear). In contrast, tryptanthrin showed no significant anti-inflammatory effect. The DCM extract inhibited oedema formation and neutrophil infiltration in subchronic inflammation in mice induced by repeated application of TPA. The extract showed activity after oral and topical administration by reducing the various parameters of the inflammatory response. The DCM extract (1 mg/ear) inhibited the delayed-type hypersensitivity (DTH) reaction induced by application of dinitrofluorobenzene (DNFB) after topical application. The response during the induction phase (24 h) was decreased by 48%, and the inflammatory phase (48 to 96 h) was reduced by 53 to 56%. The extract had no effect in this model when administered orally. The DCM extract (200 mg/kg P. O.) inhibited the acetic acid-induced writhing by 49%.     

Isobutylamides and a new methylbutylamide from Piper sarmentosum

A homologous series of six 2 E,4 E-diene-isobutylamides and a new N-2'-methylbutyl-2 E,4 E-decadieneamide were isolated from the N-hexane extract of the aerial parts of PIPER SARMENTOSUM. While the crude extract was found to possess cyclooxygenase-1 (COX-1) and 5-lipoxygenase (5-LO) inhibitory activity (COX-1 IC (50) = 19 microg/ml; 5-LO IC (50) = 10 microg/ml), the isolated compounds showed only weak effects in both test systems.     

Petasites hybridus extracts in vitro inhibit COX-2 and PGE2 release by direct interaction with the enzyme and by preventing p42/44 MAP kinase activation in rat primary microglial cells

Rhizomes of butterbur, Petasites hybridus L. (Asteraceae), have been used since ancient times for the treatment of inflammatory diseases. In the present study, the effects of lipophilic extracts from rhizomes of Petasites hybridus on the formation and release of prostaglandin E2 were investigated. The extracts had different contents of petasin and isopetasin: A: 2.1 % and 0.4 %, B: 0.2 % and 0.1 %, C: 12.1 % and 6.1 % and D: 21.9 % and 9.4 %, respectively. Direct inhibition of cyclooxygenase (COX) -1 and -2 isoenzymes and inhibition of the expression of COX-2 and p42/44 MAP kinase in rat primary microglial cells were tested. All extracts were found to be only weak direct inhibitors of COX-1 (IC50> 400 microg/mL). However, most extracts revealed a strong inhibitory activity against the inducible isoform COX-2 ( A: IC50=30.4 microg/mL; B: IC50=60.6 microg/mL; C: IC50=22.6 microg/mL; D: IC50=20.0 microg/mL). This activity was not correlated to the content of petasin and isopetasin. Pure petasin and isopetasin neither inhibited COX-1 nor COX-2 (IC50 > 400 microM for both compounds and enzymes). Petasites extracts dose-dependently inhibited LPS-induced and thus COX-2-mediated PGE2 release in primary rat microglial cells (A: IC50= 2.4 microg/mL; C: IC50=5.8 microg/mL and D: IC50=4.6 microg/mL). Also this effect was independent from the petasin and isopetasin content. COX-2 synthesis in microglia was totally blocked with 5 microg/mL of C whereas COX-1 synthesis was not influenced. C and D did not affect the LPS-induced activation of p38 MAPK and IkappaBalpha, but they prevented the LPS-induced activation of p42/44 MAPK. Therefore, these Petasites hybridus extracts can be regarded as natural selective inhibitors of COX-2 and its expression, an effect which is independent from the petasin content.     

酸模叶蓼提取物对α-葡萄糖苷酶活性影响的研究

目的:研究酸模叶蓼提取物对α-葡萄糖苷酶活性的影响。方法:采用索氏提取法提取酸模叶蓼地上部分,以96微孔板法测定各提取物对α-葡萄糖苷酶的抑制作用,并采用双倒数作图法研究酸模叶蓼甲醇提取物的酶抑制动力学特性。结果:酸模叶蓼提取物具有较好的α-葡萄糖苷酶抑制作用。酸模叶蓼甲醇提取物的抑制效果最好(IC50=2.13μg·mL-1),其次为乙酸乙酯提取物(IC50=3.826μg·mL-1),石油醚提取物抑制活性最小(IC50=230.86μg·mL-1),但均远远大于阳性对照Acarbose(IC50=1103.01μg·mL-1)的抑制活性。抑制动力学实验表明酸模叶蓼甲醇提取物的抑制类型为非竞争性抑制。结论:酸模叶蓼各提取物对α-葡萄糖苷酶活性的抑制效果均很好,具有良好的潜在开发价值。     

Further phenols and polyacetylenes from the rhizomes of Atractylodes lancea and their anti-inflammatory activity

From the rhizomes of Atractylodes lancea, 2-[(2'E)-3',7'-dimethyl-2',6'-octadienyl]-4-methoxy-6-methylphenol (1) was isolated as a new natural product. The compound showed strong inhibitory effects on 5-lipoxygenase (5-LOX) and cyclooxygenase-1 (COX-1), but exhibited only weak antioxidative activities [IC50 = 0.1 microM (5-LOX), 2 microM (COX-1), 9 microM (PMN/FMLP), 28 microM (PMNIOZ)]. Moreover, five new acetylenes were isolated and elucidated as (3Z,5E,11E)-tridecatriene-7,9-diynyl-1-O-(E)-ferulate (2), erythro-(1,3Z,11E)-tridecatriene-7,9-diyne-5,6-diyl diacetate (3), (1Z)-atractylodin (4), (1Z)-atractylodinol (5), (1Z)-acetylatractylodinol (6) plus the known (4E,6E,12E)-tetradecatriene-8,10-diyne-1,3-diyl diacetate (7). Among the acetylenes, only 2 showed strong inhibition of 5-LOX and COX-1 activity (IC50 (5-LOX) = 3 microM, IC50 (COX-1) = 1 microM). In addition, the fatty acids linoleic acid, oleic acid and palmitic acid with previously established 5-LOX-/COX-1 inhibitory actions were identified as major constituents of the n-hexane extract and thus seem to contribute to the plant's in vitro activity.     

唐古特红景天的脯氨酰寡肽酶抑制活性成分研究

目的研究唐古特红景天的脯氨酰寡肽酶抑制作用及其活性成分。方法采用改进的Kato法测定唐古特红景天水提物和从中分离得到的10个化合物的脯氨酰寡肽酶抑制作用,并采用RP-HPLC法对水提物的活性成分进行分析和指认。结果水提物的脯氨酰寡肽酶抑制活性显著(质量浓度为100 mg.L-1,抑制率为91.7%),其中,apigenin 7-O-β-D-apiofuranosyl(1→2)-β-D-glucopyr-anoside(IC50=30.4μmol.L-1)和isolariciresinol 9-O-β-D-xylopyranoside(IC50=25.2μmol.L-1)显示出较强的活性。结论唐古特红景天水提物具有显著的脯氨酰寡肽酶抑制作用,从中发现了2个主要活性成分。     

A new anti-inflammatory glucoside from Ficus racemosa L

Bioassay-guided fractionation of the ethanol extract of Ficus racemosa resulted in the identification of a new compound (rel)-4,6-dihydroxy-5-[3-methyl-(E)-propenoic acid-3-yl]-7-beta-glucopyranosyl-[2alpha,3beta-dihydrobenzofuran]-(3,2: b)-[4alpha,5beta-dihydroxy-6alpha-hydroxymethyltetrahydropyran] (racemosic acid). Racemosic acid showed potent inhibitory activity against COX-1 and 5-LOX in vitro with IC50 values of 90 and 18 microM, respectively. Racemosic acid also demonstrated a strong antioxidant activity to scavenge ABTS free radical cations with an IC50 value of 19 microM. In addition, cytotoxic effects of the extracts of F. racemosa were investigated in vitro using the ATP-based luminescence assay and results showed no cytotoxicity on the cell lines skin fibroblasts (1BR3), human Caucasian hepatocyte carcinoma (Hep G2) and human Caucasian promyelocytic leukaemia (HL-60). Bergenin was also isolated from the same active fraction.     

Composition and biological activity of different extracts from Schisandra sphenanthera and Schisandra chinensis

Plants of the Schisandraceae family contain a variety of pharmacologically active lignans like schizandrin, deoxyschizandrin, deangeloylgomisin B, gomisin A, gomisin O, gamma-schizandrin and isogomisin O. Here we have compared the composition of different polar and non-polar extracts of Schisandra sphenanthera and Schisandra chinensis. We also have screened the extracts for antiproliferative and anti-inflammatory effects in different cell-based and cell-free assays. Extracts produced with the non-polar solvents CO(2), hexane and CO(2)/5% ethanol had a similar composition. In contrast, polar extraction with ethanol provided a considerably higher yield, but a lower content of volatiles and lignans in comparison to the non-polar extracts. The proliferation of the epidermal cell lines HaCaT and A431 was dose-dependently inhibited by both the Schisandra sphenanthera and Schisandra chinensis extracts, the non-polar extracts being superior to the polar ones. The non-polar Schisandra sphenanthera extract was the most active with a half-maximal inhibitory concentration of 20 microg/mL. In a cell-free enzyme inhibition assay with recombinant cyclooxygenase-2 (COX-2) the non-polar Schisandra sphenanthera extract dose-dependently inhibited COX-2 catalysed prostaglandin (PG) production (IC(50) = 0.2 microg/mL). It also reduced the ultraviolet-B (UVB)-induced PGE (2) production (IC(50) = 4 microg/mL) and COX-2 expression in HaCaT keratinocytes. We conclude that non-polar SChisandra extracts obtained by CO(2) extraction might be useful in the prevention and treatment of hyperproliferative and inflammatory skin diseases.     

Xanthine oxidase inhibitory activity of Vietnamese medicinal plants

Among 288 extracts, prepared from 96 medicinal plants used in Vietnamese traditional medicine to treat gout and related symptoms, 188 demonstrated xanthine oxidase (XO) inhibitory activity at 100 microg/ml, with 46 having greater than 50% inhibition. At 50 microg/ml, 168 of the extracts were active, with 21 possessing more than 50% inhibition. At 25 microg/ml, 146 extracts exhibited inhibitory activity, with 8 showing over 50% inhibition, while 126 extracts presented activity at 10 microg/ml, with 2 having greater than 50% inhibition. The MeOH extracts of Artemisia vulgaris, Caesalpinia sappan (collected at the Seven-Mountain area), Blumea balsamifera (collected in Lam Dong province), Chrysanthemum sinense and MeOH-H(2)O extract of Tetracera scandens (Khanh Hoa province) exhibited strong XO inhibitory activity with IC(50) values less than 20 microg/ml. The most active extract was the MeOH extract of the flower of C. sinense with an IC(50) value of 5.1 microg/ml. Activity-guided fractionation of the MeOH extract led to the isolation of caffeic acid (1), luteolin (2), eriodictyol (3), and 1,5-di-O-caffeoylquinic acid (4). All these compounds showed significant XO inhibitory activity in a concentration-dependent manner, and the activity of 2 was more potent (IC(50) 1.3 microM) than the clinically used drug, allopurinol (IC(50) 2.5 microM).     

Quantification of active principles and pigments in leaf extracts of Isatis tinctoria by HPLC/UV/MS

An HPLC method has been developed and validated for the quantification of the pharmacologically active principles tryptanthrin (1), 1,3-dihydro-3-[(4-hydroxy-3,5-dimethoxyphenyl)methylene]-2 H-indol-2-one (indolinone) (3), indirubin (4), alpha-linolenic acid (2), and indigo (5), an isomer of indirubin, in extracts from the traditional anti-inflammatory plant Isatis tinctoria (woad). The chromatographic separation was performed on a C-18 column with a linear gradient of acetonitrile in water containing 0.1% formic acid. The method combines UV and electrospray MS detection in the positive ion mode for the detection of the alkaloids, with a switch to the negative mode for the analysis of alpha-linolenic acid. The method was applied to the analysis of woad extracts obtained by supercritical fluid (SFE) CO2 extraction, and by pressurized liquid extraction (PLE) with dichloromethane and methanol, respectively. While the highest concentration of alpha-linolenic acid was found in the SFE extract (7.43%), the concentrations of tryptanthrin , indolinone, indirubin and indigo were the highest in the dichloromethane extract (0.30, 0.035, 2.48 and 0.84%, respectively). Compound 3 was not detected in the methanolic extract and only traces of compounds 1, 4 and 5 and low amount of alpha-linolenic acid (0.39%) were present in this extract.     

Iridoids with anti-inflammatory activity from Vitex peduncularis

A new iridoid, pedunculariside, together with the known iridoid agnuside were isolated from the butanol extract of Vitex peduncularis stem bark. Both pedunculariside and agnuside showed preferential inhibition of COX-2, with IC50 values of 0.15 +/- 0.21 mg/ml and 0.026 +/- 0.015 mg/ml respectively, while having only small inhibitory effects on COX-1. Both compounds did not exhibit cytotoxicity against vero cells.     

Synthesis and structure-activity relationship studies of 1,3-diarylprop-2-yn-1-ones: dual inhibitors of cyclooxygenases and lipoxygenases

A group of 1,3-diarylprop-2-yn-1-ones (13, 17, 23, 26 and 27) possessing a C-3 p-SO2Me COX-2 pharmacophore were designed, synthesized and evaluated as potential dual inhibitors of cyclooxygenase-1/2 (COX-1/2) and 5/15-lipoxygenases (5/15-LOX) that exhibit vivo antiinflammatory and analgesic activities. Among this class of compounds, 3-(4-methanesulfonylphenyl)-1-(4-fluorophenyl)prop-2-yn-1-one (13h) was identified as a potent and selective inhibitor of COX-2 (COX-2 IC50 = 0.1 microM; SI = 300), being 5-fold more potent than rofecoxib (COX-2 IC50 = 0.5 microM; SI > 200). In a rat carrageenan-induced paw edema assay 13h exhibited moderate antiinflammatory activity (26% inhibition of inflammation) at 3 h after administration of a 30 mg/kg oral dose. A related dual COX-1/2 and 5/15-LOX inhibitor 3-(4-methanesulfonylphenyl)-1-(4-cyanophenyl)prop-2-yn-1-one (13g, COX-1 IC50 = 31.5 microM; COX-2 IC50 = 1.0 microM; SI = 31.5; 5-LOX IC50 = 1.0 microM; 15-LOX IC50 = 3.2 microM) exhibited more potent antiinflammatory activity (ED50 = 90 mg/kg), being superior to the reference drug aspirin (ED50 = 129 mg/kg). Within this group of compounds 3-(4-methanesulfonylphenyl)-1-(4-isopropylphenyl)prop-2-yn-1-one (13e) emerged as having an optimal combination of in vitro COX-1/2 and 5/15-LOX inhibitory effects (COX-1 IC50 = 9.2 microM; COX-2 IC50 = 0.32 microM; SI = 28; 5-LOX IC50 = 0.32 microM; 15-LOX IC50 = 0.36 microM) in conjunction with a good antiinflammatory activity (ED50 = 35 mg/kg) compared to the reference drug celecoxib (ED50 = 10.8 mg/kg) when administered orally. A molecular modeling study where 13e was docked in the COX-2 binding site indicated the C-1 p-i-Pr group was positioned within a hydrophobic pocket (Phe205, Val344, Val349, Phe381 and Leu534), and that this positioning of the i-Pr group facilitated orientation of the C-3 p-SO2Me COX-2 pharmacophore such that it inserted into the COX-2 secondary pocket (His90, Arg513, Ile517 and Val523). A related docking study of 13e in the 15-LOX binding site indicates that the C-3 p-SO2Me COX-2 pharmacophore was positioned in a region closer to the catalytic iron site where it undergoes a hydrogen bonding interaction with His541 and His366, and that the C-1 p-i-Pr substituent is buried deep in a hydrophobic pocket (Ile414, Ile418, Met419 and Ile593) near the base of the 15-LOX binding site.     

Cyanobacterial nodularin is a potent inhibitor of type 1 and type 2A protein phosphatases.

The present study characterizes the inhibitory effects of nodularin, a recently isolated hepatotoxic compound from the cyanobacterium Nodularia spumigena, on type 1 (PP1), type 2A, (PP2A), type 2B (PP2B), and type 2C (PP2C) protein phosphatases. Both PP2A and PP1 were potently inhibited (IC50 = 0.026 and 1.8 nM, respectively) by nodularin, whereas PP2B was inhibited to a lesser extent (IC50 = 8.7 microM). Nodularin had no apparent effect on PP2C, alkaline phosphatase, acid phosphatase, insulin receptor tyrosine kinase, protein kinase A, phosphorylase kinase, or protein kinase C. In a whole-cell extract of T51B liver cells, nodularin inhibited PP1 and PP2A activity with a potency similar to that seen with their purified catalytic subunits. Thus, due to the high specificity of nodularin for PP2A and PP1, this hepatotoxin may prove to be useful as a probe for distinguishing the activity of these protein phosphatases in cell extracts.     

Platelet aggregation and anti-inflammatory effects of garden pea, Desi chickpea and Kabuli chickpea

Inflammation is the natural body defense mechanism for the removal of injurious agents, necrosed cells and tissues from the body. This study was aimed to evaluate the anti-inflammatory and platelet aggregation effects of three medicinal plants of Pakistan. Methanolic extract of garden pea inhibited arachidonic acid (AA)-induced platelet aggregation (IC50 = 35 microg/mL) and platelet activating factor (PAF)-induced platelet aggregation (IC50 = 38 microg/mL) in a dose dependent fashion. Methanolic extract of Desi chickpea inhibited arachidonic acid (AA) induced platelet aggregation (IC50 value = AA = 46 microg/mL) in dose dependent fashion while was found not active against PAF-induced platelet aggregation. Methanolic extract of Kabuli chickpea was found not active against both arachidonic acid (AA)-induced platelet aggregation and PAF-induced platelet aggregation. The best potential to inhibit in vitro COX-2 activity showed garden pea (Pisum sativum: the synthesis of PGE2 reduced by 92% in comparison with untreated control wells) followed by Desi chickpea (Cicer arietinum var; 87% inhibition) and Kabuli chickpea extracts (Cicer arietinum var: 65% inhibition). All extracts were tested at concentration 20 microg/mL. in COX-2 assay. The results indicate that if the same were happening in vito, Garden pea, Desi chickpea and Kabuli chickpea could be useful as natural antithrombotic anti-inflammatory materials.     

Synthesis and biological evaluation of 3-(1H-imidazol- and triazol-1-yl)-2,2-dimethyl-3-[4-(naphthalen-2-ylamino)phenyl]propyl derivatives as small molecule inhibitors of retinoic acid 4-hydroxylase (CYP26)

The synthesis and potent inhibitory activity of novel 3-(1H-imidazol- and triazol-1-yl)-2,2-dimethyl-3-(4-(naphthalen-2-ylamino)phenyl)propyl derivatives vs a MCF-7 CYP26A1 microsomal assay is described. This study focused on the effect of modifying the heme binding azole group and the flexible C3 chain on inhibitory activity and selectivity. The most promising inhibitor 2,2-dimethyl-3-[4-(naphthalen-2-ylamino)-phenyl]-3-[1,2,4]triazol-1-yl-propionic acid methyl ester (17) (IC(50) = 0.35 nM as compared with liarozole IC(50) = 540 nM and R116010 IC(50) = 10 nM) was evaluated for CYP selectivity and hepatic stability. Compounds with CYP26 inhibitory IC(50) values ≤50 nM enhanced the biological activity of exogenous ATRA, as evidenced by a 3.7-5.8-fold increase in CYP26A1 mRNA in SH-SY5Y neuroblastoma cells as compared with ATRA alone. All compounds demonstrated an activity comparable with or better than R116010, and the induction correlated well with CYP26 inhibition data. These studies highlight the promising activity profile of this novel CYP26 inhibitor and suggest it as an appropriate candidate for future development.     

Selective COX-2 inhibition by a Pterocarpus marsupium extract characterized by pterostilbene, and its activity in healthy human volunteers

In this study, an extract of Pterocarpus marsupium Roxb. containing pterostilbene has been evaluated for its PGE2-inhibitory activity in LPS-stimulated PBMC. In addition, the COX-1/2 selective inhibitory activity of P. marsupium (PM) extract was investigated. Biological activity, as well as safety of PM extract was evaluated in healthy human volunteers. PM extract, pterostilbene and resveratrol inhibited PGE2 production from LPS-stimulated human peripheral blood mononuclear cells (PBMC) with IC50 values of 3.2 +/- 1.3 microg/mL, 1.0 +/- 0.6 microM and 3.2 +/- 1.4 microM, respectively. When pterostilbene content of PM extract is calculated, PGE2 production inhibition of PM extract is comparable to PGE2 production inhibition of purified pterostilbene. Furthermore, in a COX-1 whole blood assay (WBA) PM extract was not effective while in a COX-2 WBA, PM extract decreased PGE2 production indicating COX-2 specific inhibition. In healthy human volunteers, the oral use of 450 mg PM extract did not decrease PGE2 production ex vivo in a WBA. Pterostilbene levels in serum were increased, but were 5-fold lower than the observed IC50 for PGE2 inhibition in LPS-stimulated PBMC. No changes from base-line of the safety parameters were observed and no extract-related adverse events occurred during the study. In conclusion, this is the first study to describe the selective COX-2 inhibitory activity of a Pterocarpus marsupium extract. Moreover, the PGE2 inhibitory activity of PM extract was related to its pterostilbene content. In humans, 450 mg PM extract resulted in elevated pterostilbene levels in serum, which were below the active concentration observed in vitro. In addition, short-term supplementation of 450 mg PM extract is considered to be a safe dose based on the long history of use, the absence of abnormal blood cell counts and blood chemistry values and the absence of extract-related adverse events. This strongly argues for a dose-finding study of PM extract in humans to corroborate the in vitro observed inhibitory activity on PGE2 production in order to resolve the potential use of PM extract in inflammatory disorders and/or inflammatory pain.     

Synthesis and antiplatelet activity of new imidazole-4-carboxylic acid derivatives

1-Arylalkyl-5-phenylsulfonamino-imidazole-4-carboxylic acid esters and their carboxamides with an additional secondary amino group were synthesized and identified as antiplatelet agents in a low micromolar range (Born-test, inducer collagen). To describe the mechanism of action more precisely the Born-test was carried out as well with ADP, adrenaline or PAF, respectively. In addition, two compounds were investigated for their COX-1 inhibitory activities. Provided the essential structural criteria are met i.e. amide group or ester, sulfonylamino rest, hydrophobic moieties, and a secondary amino function, slight structural modifications are able to shift the pattern of activity among the above platelet receptors. So, the ester 5c exhibits PAF antagonistic activity at IC(50) = 1 microM and COX-1 inhibition (IC(50) = 0.4 microM). The carboxamide 6c shows ADP antagonistic properties (IC(50) = 2 microM). Compound 6g is as well PAF antagonistic (IC(50) = 4 microM) and a COX-1 inhibitor (IC(50) = 1 microM). The derivative 6i shows a strong antiadrenergic (IC(50) = 0.15 microM) and PAF antagonistic (IC(50) = 0.66 microM) effect.     

Inhibition by licochalcone A, a novel flavonoid isolated from liquorice root, of IL-1beta-induced PGE2 production in human skin fibroblasts

Licochalcone A, a novel flavonoid isolated from the root of Glycyrrhiza inflata, has been reported to exhibit anti-inflammatory activity in animal models. In this study, we examined the effect of licochalcone A on the production of chemical mediators such as prostaglandin (PG)E2 and cytokines by interleukin (IL)-1beta in human skin fibroblasts. Licochalcone A (IC50 15.0 nM) inhibited PGE2 production, but not IL-6 and IL-8 production, in response to IL-1beta. NS-398 (IC50 1.6 nM), a COX-2 selective inhibitor, also suppressed the PGE2 production. Furthermore, licochalcone A and NS-398 suppressed PGF(2alpha) production by IL-1beta. However, licochalcone A (1 microM) had no effect on increased levels of cyclooxygenase (COX)-2 mRNA and protein in cells. Dexamethasone (100 nM) not only inhibited PGE2, PGF(2alpha), IL-6 and IL-8 production but also strongly suppressed the expression of COX-2 mRNA and protein. Licochalcone A had no effect on COX-1-dependent PGE2 production, whereas indometacin (100 nM), a dual inhibitor of COX-1 and COX-2, was very effective. These results suggest that licochalcone A induces an anti-inflammatory effect through the inhibition of COX-2-dependent PGE2 production. Furthermore, it appears that the inhibitory effect of licochalcone A on PGE2 production in response to IL-1beta is quite different from that of the steroid.     

1,3-Diaryl-4,5,6,7-tetrahydro-2H-isoindole derivatives: a new series of potent and selective COX-2 inhibitors in which a sulfonyl group is not a structural requisite

Novel tetrahydro-2H-isoindoles have been prepared and evaluated as inhibitors of the COX-2 isoenzyme. A 1,3-diaryl substitution on the central polycyclic ring system and absence of a sulfonyl moiety are the two structural features of this chemical series. A short and easy synthetic pathway produced several derivatives which were shown to be potent and selective COX-2 vs COX-1 inhibitors (IC(50) = 0. 6-100 nM for COX-2, 100->1000 nM for COX-1). Structural modifications established that a bicyclic ring appended to the pyrrole nucleus and 4,4'-difluoro substitution on the phenyl rings were optimal for high inhibitory potency. Activity was confirmed in the human whole blood assay and subsequently in the murine air-pouch model in which in vivo PGE2 inhibitory activity was evaluated with respect to gastric tolerance (ED(50) for inhibition of exudate PGE2 of 3 mg/kg and gastric PGE2 of 20 mg/kg). Gastric tolerance was further assessed after administration to mice of high doses (up to 400 mg/kg) of the inhibitors by measurement of gastric damage. This panel of studies allowed selection of a number of tetrahydro-2H-isoindoles which were compared in the adjuvant-induced arthritis model. Compounds 32 and 37 showed the most potent activity with ED(50) values for edema inhibition in the noninjected paw of 0. 35 and 0.15 mg/kg/day, respectively, after oral administration. In addition, this interesting antiinflammatory profile was accompanied by a protective effect against arthritis-induced osteopenia, the decrease being 50% with a dose of 0.25 mg/kg/day.