Deciphering the mechanism behind the varied binding activities of COXIBs through Molecular Dynamic Simulations,MM-PBSA binding energy calculations and per-residue energy decomposition studies

COX-2 is a well-known drug target in inflammatory disorders. COX-1/COX-2 selectivity of NSAIDs is crucial in assessing the gastrointestinal side effects associated with COX-1 inhibition. Celecoxib, rofecoxib, and valdecoxib are well-known specific COX-2 inhibiting drugs. Recently, polmacoxib, a COX-2/CA-II dual inhibitor has been approved by the Korean FDA. These COXIBs have similar structure with diverse activity range. Present study focuses on unraveling the mechanism behind the 10-fold difference in the activities of these sulfonamide-containing COXIBs. In order to obtain insights into their binding with COX-2 at molecular level, molecular dynamics simulations studies, and MM-PBSA approaches were employed. Further, per-residue decomposition of these energies led to the identification of crucial amino acids and interactions contributing to the differential binding of COXIBs. The results clearly indicated that Leu338, Ser339, Arg499, Ile503, Phe504, Val509, and Ser516 (Leu352, Ser353, Arg513, Ile517, Phe518, Val523, and Ser530 in PGHS-1 numbering) were imperative in determining the activity of these COXIBs. The binding energies and energy contribution of various residues were similar in all the three simulations. The results suggest that hydrogen bond interaction between the hydroxyl group of Ser516 and five-membered ring of diarylheterocycles augments the affinity in COXIBs. The SAR of the inhibitors studied and the per-residue energy decomposition values suggested the importance of Ser516. Additionally, the positive binding energy obtained with Arg106 explains the binding of COXIBs in hydrophobic channel deep in the COX-2 active site. The findings of the present work would aid in the development of potent COX-2 inhibitors.     

Design,Synthesis and Biological Evaluation of New N-Acyl Hydrazones with a Methyl Sulfonyl Moiety as Selective COX-2 Inhibitors

The mechanism of action of nonsteroidal anti-inflammatory drugs (NSAIDs) is inhibition of specific prostaglandin (PG) synthesis by inhibition of cyclooxygenase (COX) enzymes. The two COX isoenzymes show 60 % similarity. It is known that the nonspecific side effects of conventional NSAIDs are physiologically caused by inhibition of the COX-1 enzyme. Therefore, the use of COX-2 selective inhibitors is seen to be a more beneficial approach in reducing these negative effects. However, some of the existing COX-2 selective inhibitors show cardiovascular side effects. Therefore, studies on the development of new selective COX-2 inhibitors remain necessary. It is important to develop new COX-2 inhibitors in the field of medicinal chemistry. Accordingly, novel N-acyl hydrazone derivatives were synthesized as new COX-2 inhibitors in this study. The hydrazone structure, also known for its COX activity, is important in terms of many biological activities and was preferred as the main structure in the design of these compounds. A methyl sulfonyl pharmacophore was added to the structure in order to increase the affinity for the polar side pocket present in the COX-2 enzyme. It is known that methyl sulfonyl groups are suitable for polar side pockets. The synthesis of the compounds ( 3a – 3j ) was characterized by spectroscopic methods. Evaluation of in vitro COX-1/COX-2 enzyme inhibition was performed by fluorometric method. According to the enzyme inhibition results, the obtained compounds displayed the predicted selectivity for COX-2 enzyme inhibition. Compound 3j showed important COX-2 inhibition with a value of IC₅₀=0.143 uM. Interaction modes between the COX-2 enzyme and compound 3j were investigated by docking studies.     

Anti-cancer effects of celecoxib on nasopharyngeal carcinoma HNE-1 cells expressing COX-2 oncoprotein

Celecoxib is a selective cyclooxygenase-2 (COX-2) inhibitor with antitumor and antiangiogenic activities. To investigate the effects of celecoxib on nasopharyngeal carcinoma (NPC), HNE-1 cells were treated with celecoxib at various concentrations. MTT assay, migration assay and invasion assay were performed to observe the inhibitory activity of celecoxib on HNE-1 cells. Additionally, VEGF-A expression and radiation survival of NPC cell were also examined after treatment with celecoxib. Celecoxib treatment presented an anti-proliferation function in a time and dose-dependent manner on HNE-1 cells which highly express COX-2 protein. Celecoxib also displayed an obvious inhibitory activity on invasive capacity of NPC cells. Moreover, the celecoxib’s effects to suppress VEGF-A expression and enhance radiosensitivity were detected in HNE-1 cells. These findings implicate that application of celecoxib may be an effective strategy for NPC therapy.     

New phenolic cinnamic acid derivatives as selective COX-2 inhibitors. Design,synthesis, biological activity and structure-activity relationships

Selective inhibition of cyclooxygenase (COX)-2 enzyme is an important achievement when looking for potent anti-inflammatory agents, with fewer gastrointestinal side effects. In this work, a new series of cinnamic acid derivatives, namely hexylamides, have been designed, synthesized and evaluated in human blood for their inhibitory activity of COX-1 and COX-2 enzymes. From this, new structure-activity relationships were built, showing that phenolic hydroxyl groups are essential for both COX-1 and COX-2 inhibition. Furthermore, the presence of bulky hydrophobic di-tert-butyl groups in the phenyl ring strongly contributes for selective COX-2 inhibition. In addition, a correlation with the theoretical log P has been carried out, showing that lipophilicity is particularly important for COX-2 inhibition. Further, a plasma protein binding (PPB) prediction has been performed revealing that PPB seems to have no influence in the activity of the studied compounds. From the whole study, effective selective inhibitors of COX-2 were found, namely compound 9 (IC₅₀ = 3.0 ± 0.3 μM), 10 (IC₅₀ = 2.4 ± 0.6 μM) and 23 (IC₅₀ = 1.09 ± 0.09 μM). Those can be considered starting point hit compounds for further optimization as potential non-steroidal anti-inflammatory drugs.     

The amino acid sequence of human chorionic gonadotropin. The alpha subunit and beta subunit.

The amino acid sequences of both the alpha and beta subunits of human chorionic gonadotropin have been determined. The amino acid sequence of the alpha subunit is: Ala - Asp - Val - Gln - Asp - Cys - Pro - Glu - Cys-10 - Thr - Leu - Gln - Asp - Pro - Phe - Ser - Gln-20 - Pro - Gly - Ala - Pro - Ile - Leu - Gln - Cys - Met - Gly-30 - Cys - Cys - Phe - Ser - Arg - Ala - Tyr - Pro - Thr - Pro-40 - Leu - Arg - Ser - Lys - Lys - Thr - Met - Leu - Val - Gln-50 - Lys - Asn - Val - Thr - Ser - Glu - Ser - Thr - Cys - Cys-60 - Val - Ala - Lys - Ser - Thr - Asn - Arg - Val - Thr - Val-70 - Met - Gly - Gly - Phe - Lys - Val - Glu - Asn - His - Thr-80 - Ala - Cys - His - Cys - Ser - Thr - Cys - Tyr - Tyr - His-90 - Lys - Ser. Oligosaccharide side chains are attached at residues 52 and 78. In the preparations studied approximately 10 and 30% of the chains lack the initial 2 and 3 NH2-terminal residues, respectively. This sequence is almost identical with that of human luteinizing hormone (Sairam, M. R., Papkoff, H., and Li, C. H. (1972) Biochem. Biophys. Res. Commun. 48, 530-537). The amino acid sequence of the beta subunit is: Ser - Lys - Glu - Pro - Leu - Arg - Pro - Arg - Cys - Arg-10 - Pro - Ile - Asn - Ala - Thr - Leu - Ala - Val - Glu - Lys-20 - Glu - Gly - Cys - Pro - Val - Cys - Ile - Thr - Val - Asn-30 - Thr - Thr - Ile - Cys - Ala - Gly - Tyr - Cys - Pro - Thr-40 - Met - Thr - Arg - Val - Leu - Gln - Gly - Val - Leu - Pro-50 - Ala - Leu - Pro - Gin - Val - Val - Cys - Asn - Tyr - Arg-60 - Asp - Val - Arg - Phe - Glu - Ser - Ile - Arg - Leu - Pro-70 - Gly - Cys - Pro - Arg - Gly - Val - Asn - Pro - Val - Val-80 - Ser - Tyr - Ala - Val - Ala - Leu - Ser - Cys - Gln - Cys-90 - Ala - Leu - Cys - Arg - Arg - Ser - Thr - Thr - Asp - Cys-100 - Gly - Gly - Pro - Lys - Asp - His - Pro - Leu - Thr - Cys-110 - Asp - Asp - Pro - Arg - Phe - Gln - Asp - Ser - Ser - Ser - Ser - Lys - Ala - Pro - Pro - Pro - Ser - Leu - Pro - Ser-130 - Pro - Ser - Arg - Leu - Pro - Gly - Pro - Ser - Asp - Thr-140 - Pro - Ile - Leu - Pro - Gln. Oligosaccharide side chains are found at residues 13, 30, 121, 127, 132, and 138. The proteolytic enzyme, thrombin, which appears to cleave a limited number of arginyl bonds, proved helpful in the determination of the beta sequence.     

The primary structure of the β-subunit of protocatechuate 3,4-dioxygenase from Pseudomonas aeruginosa

The complete amino acid sequence of the β-subunit of protocatechuate 3,4-dioxygenase was determined. The β-subunit contained four methionine residues. Thus, five peptides were obtained after cleavage of the carboxymethylated β-subunit with cyanogen bromide, and were isolated on Sephadex G-75 column chromatography. The amino acid sequences of the cyanogen bromide peptides were established by characterization of the peptides obtained after digestion with trypsin, chymotrypsin, thermolysin, or Staphylococcus aureus protease. The major sequencing techniques used were automated and manual Edman degradations. The five cyanogen bromide peptides were aligned by means of the amino acid sequences of the peptides containing methionine purified from the tryptic hydrolysate of the carboxymethylated β-subunit. The amino acid sequence of all the 238 residues was as follows: ProAlaGlnAspAsnSerArgPheValIleArgAsp ArgAsnTrpHis ProLysAlaLeuThrPro-Asp — TyrLysThrSerIleAlaArg SerProArgGlnAla LeuValSerIleProGlnSer — IleSerGluThrThrGly ProAsnPheSerHisLeu GlyPheGlyAlaHisAsp-His — AspLeuLeuLeuAsnPheAsn AsnGlyGlyLeu ProIleGlyGluArgIle-Ile — ValAlaGlyArgValValAsp GlnTyrGlyLysPro ValProAsnThrLeuValGluMet — TrpGlnAlaAsnAla GlyGlyArgTyrArg HisLysAsnAspArgTyrLeuAlaPro — LeuAspProAsn PheGlyGlyValGly ArgCysLeuThrAspSerAspGlyTyrTyr — SerPheArg ThrIleLysProGlyPro TyrProTrpArgAsnGlyProAsnAsp — TrpArgProAla HisIleHisPheGlyIle SerGlyProSerIleAlaThr-Lys — LeuIleThrGlnLeuTyr PheGluGlyAspPro LeuIleProMetCysProIleVal — LysSerIleAlaAsn ProGluAlaValGlnGln LeuIleAlaLysLeuAspMetAsnAsn — AlaAsnProMet AsnCysLeuAlaTyr ArgPheAspIleValLeuArgGlyGlnArgLysThrHis PheGluAsnCys. The sequence published earlier in summary form (Iwaki et al., 1979, J. Biochem.86, 1159–1162) contained a few errors which are pointed out in this paper.     

Phenolcarboxylic acids from medicinal herbs exert anticancer effects through disruption of COX-2 activity

Integrated research of herbs and formulas characterized by functions of promoting blood circulation and removing blood stasis is one of the most active fields in traditional Chinese medicine. This paper strives to demonstrate the roles of a homologous series of phenolcarboxylic acids from these medicinal herbs in cancer treatment via targeting cyclooxygenase-2 (COX-2), a well-recognized mediator in tumorigenesis. We selected thirteen typical phenolcarboxylic acids (benzoic acid derivatives, cinnamic acid derivatives and their dehydration-condensation products), and found gallic acid, caffeic acid, danshensu, rosmarinic acid and salvianolic acid B showed 50% inhibitory effects on hCOX-2 activity and A549 cells proliferation. 2D-quantitative method was introduced to describe the potential structural features that contributed to certain bioactivities. We also found these compounds underwent responsible hydrogen bonding to Arg120 and Ser353 in COX-2 active site residues. We further extensively focused on danshensu [d-(+)-β-(3,4-dihydoxy-phenylalanine)] or DSS, which exerted COX-2 dependent anticancer manner. Both genetic and pharmacological inhibition of COX-2 could enhance the ability of DSS inhibiting A549 cells growth. Additionally, COX-2/PGE₂/ERK signaling axis was essential for the anticancer effect of DSS. Furthermore, combined treatment with DSS and celecoxib could produce stronger anticancer effects in experimental lung metastasis of A549 cells in vivo. All these findings indicated that phenolcarboxylic acids might possess anticancer effects through jointly targeting COX-2 activity in cancer cells and provided strong evidence in cancer prevention and therapy for the herbs characterized by blood-activating and stasis-resolving functions in clinic.     

Design and synthesis of acyclic triaryl (Z)-olefins: a novel class of cyclooxygenase-2 (COX-2) inhibitors

A group of acyclic 2-alkyl-1,1-diphenyl-2-(4-methylsulfonylphenyl)ethenes was designed for evaluation as selective cyclooxygenase-2 (COX-2) inhibitors. In vitro COX-1 and COX-2 isozyme inhibition structure-activity studies identified 1,1-diphenyl-2-(4-methylsulfonylphenyl)hex-1-ene as a highly potent (IC(50) = 0.014 microM), and an extremely selective [COX-2 selectivity index (SI) > 7142], COX-2 inhibitor that showed superior anti-inflammatory (AI) activity (ID(50) = 2.5 mg/kg) relative to celecoxib (ID(50) = 10.8 mg/kg). This initial study was extended to include the design of a structurally related group of acyclic triaryl (Z)-olefins possessing an acetoxy (OAc) substituent at the para-position of the C-1 phenyl ring that is cis to a C-2 4-methylsulfonylphenyl substituent. COX-1 and COX-2 inhibition studies showed that (Z)-1-(4-acetoxyphenyl)-1-phenyl-2-(4-methylsulfonylphenyl)but-1-ene [(Z)-13b] is a potent (COX-1 IC(50) = 2.4 microM; COX-2 IC(50) = 0.03 microM), and selective (COX-2 SI = 81), COX-2 inhibitor which is a potent AI agent (ID(50) = 4.1mg/kg) with equipotent analgesic activity to celecoxib. A molecular modeling (docking) study showed that the SO(2)Me substituent of (Z)-13b inserts deep inside the 2 degrees -pocket of the COX-2 active site, where one of the O-atoms of SO(2) group undergoes a H-bonding interaction with Phe(518). The p-OAc substituent on the C-1 phenyl ring is oriented in a hydrophobic pocket comprised of Met(522), Gly(526), Trp(387), Tyr(348), and Tyr(385), and the C-2 ethyl substituent is oriented towards the mouth of the COX-2 channel in the vicinity of amino acid residues Arg(120), Leu(531), and Val(349). Structure-activity data acquired indicate that a (Z)-olefin having cis C-1 4-acetoxyphenyl (phenyl) and C-2 4-methylsulfonylphenyl substituents, and a C-1 phenyl substituent in conjunction with either a C-2 hydrogen or short alkyl substituent provides a novel template to design acyclic olefinic COX-2 inhibitors that, like aspirin, have the potential to acetylate COX-2.     

COX-2 regulates the proliferation of glioma stem like cells

Cancer stem-like cells (CSCs) possessing features of neural precursor cells (NPC) influence initiation, recurrence and chemoresistance of glioblastoma multiforme (GBM). As inflammation is crucial for glioblastoma progression we investigated the effect of chronic IL-1β treatment on CSCs derived from glioblastoma cell line U87MG. Exposure to IL-1β for 10 days increased (i) accumulation of 8-OHdG - a key biomarker of oxidative DNA damage; (ii) DNA damage response (DDR) indicators γH2AX, ATM and DNA-PK; (iii) nuclear and cytoplasmic p53 and COX-2 levels and (iv) interaction between COX-2 and p53. Despite upregulating p53 expression IL-1β had no effect on cell cycle progression, apoptosis or self renewal capacity of CSCs. COX-2 inhibitor Celecoxib reduced self renewal capacity and increased apoptosis of both control and IL-1β treated CSCs. Therefore the ability of COX-2 to regulate proliferation of CSCs irrespective of exposure to IL-1β, warrants further investigation of COX-2 as a potential anti-glioma target.     

Indolyl esters and amides related to indomethacin are selective COX-2 inhibitors

Previous studies from our laboratory have revealed that esterification/amidation of the carboxylic acid moiety in the nonsteroidal anti-inflammatory drug, indomethacin, generates potent and selective COX-2 inhibitors. In the present study, a series of reverse ester/amide derivatives were synthesized and evaluated as selective COX-2 inhibitors. Most of the reverse esters/amides displayed time-dependent COX-2 inhibition with IC₅₀ values in the low nanomolar range. Replacement of the 4-chlorobenzoyl group on the indole nitrogen with a 4-bromobenzyl moiety resulted in compounds that retained selective COX-2 inhibitory potency. In addition to inhibiting COX-2 activity in vitro, the reverse esters/amides also inhibited COX-2 activity in the mouse macrophage-like cell line, RAW264.7. Overall, this strategy broadens the scope of our previous methodology of neutralizing the carboxylic acid group in NSAIDs as a means of generating COX-2-selective inhibitors and is potentially applicable to other NSAIDs.     

COX-2 and iNOS in opioid-induced delayed cardioprotection in the intact rat

Cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) have been previously implicated in the late phase of cardioprotection associated with opioid-induced and ischemic preconditioning (IPC) in conscious rabbits and COX-2 in isolated rat hearts pretreated with an exogenous delta opioid agonist. However, it is not know if both iNOS and COX-2 mediate the late phase of cardioprotection induced by opioids in the intact blood-perfused rat. Therefore, we investigated the role of COX-2 and iNOS in the delayed phase of protection mediated by delta opioid receptor activation. Rats were pretreated 24 hours prior to an occlusion/reperfusion protocol with the selective non-peptide delta opioid agonists, BW373U86 (BW) and SNC-121 (SNC). NS-398, a selective COX-2 inhibitor was administered after the 24-hour recovery period just prior to index ischemia. The selective iNOS inhibitors, S-methylthiourea (SMT) and aminoguanidine (AG), were administered in conjunction with opioid pretreatment or were also given 24 hours after opioid administration just prior to index ischemia. COX-2 inhibition by NS-398 given 24 hours after opioid administration attenuated the protective effects of both BW and SNC (46 +/- 6 vs. 13 +/- 3 and 51 +/- 5 vs. 29 +/- 2, p < 0.001, respectively). Similarly, inhibition of iNOS following 24 hours of treatment with opioids also attenuated the protective effects of BW and SNC. However, the delayed protective effects of the opioids were not attenuated by pretreatment with the iNOS inhibitors 24 hours prior to the infarct protocol. These results suggest that both COX-2 and iNOS are mediators of delayed protection induced by non-peptide delta opioid agonists. It appears that the trigger effect is not dependent on the activity of iNOS or COX-2 but the late phase of cardioprotection is dependent on the upregulation of these enzymes.     

铁筷子提取物对肿瘤细胞增殖及COX-2 mRNA表达的抑制作用

研究不同铁筷子提取物对肿瘤细胞增殖及 COX-2 mRNA 表达的抑制作用。以铁筷子醇总提取物(TKZ1)、正丁醇萃取部位(TKZ2)、乙酸乙酯萃取部位(TKZ3)分别作用于 DU145、PC3、HeLa、HT-29、HepG2等肿瘤细胞,应用噻唑蓝实验(MTT 法)计算其对细胞增殖的抑制作用,应用荧光定量 PCR 技术检测TKZ1、TKZ2、TKZ3处理后的各肿瘤细胞中 COX-2 mRNA 的表达情况。结果表明：TKZ1、TKZ2、TKZ3均能显著抑制多种肿瘤细胞的增殖,与阴性对照组比较,其可以在 mRNA 水平上抑制 COX-2的表达,且呈明显的量效关系。说明铁筷子提取物对体外肿瘤细胞的增殖具有显著的抑制作用,其抗瘤机制可能与抑制肿瘤细胞中 COX-2 mRNA 的表达有关。     

Novel pyrazoline derivatives as bi-inhibitor of COX-2 and B-Raf in treating cervical carcinoma

Twenty four pyrazoline derivatives modified from Celecoxib were designed and synthesized as bi-inhibitor of COX-2 and B-Raf. They were evaluated for their COX-1/COX-2/B-Raf inhibitory and anti-proliferation activities. Compound A3 displayed the most potent activity against COX-2 and HeLa cell line (IC₅₀ = 0.008 μM; GI₅₀ = 19.86 μM) and showed superb COX-1/COX-2 selectivity (>500), being more potent and selective than positive control Celecoxib or 5-fluorouracil. Compounds A5 and B5 were introduced best B-Raf inhibitory activities (IC₅₀ = 0.15 μM and 0.12 μM, respectively). Compound A4 retained superb bioactivity against COX-2 and HeLa cell line (IC₅₀ = 0.015 μM; GI₅₀ = 23.82 μM) and displayed moderate B-Raf inhibitory activity (IC₅₀ = 3.84 μM). Docking simulation was conducted to give binding patterns. QSAR models were built using bioactivity data and optimized conformations to provide a future modification of COX-2/B-Raf inhibitors.     

The association of polymorphisms in DNA base excision repair genes <Emphasis Type="Italic">XRCC1</Emphasis>, <Emphasis Type="Italic">OGG1</Emphasis> and <Emphasis Type="Italic">MUTYH</Emphasis> with the risk of childhood acute lymphoblastic leukemia

The aim of this study was to evaluate the association of polymorphisms in genes encoding three key proteins of DNA base excision repair (BER): the OGG1 Ser326Cys, the MUTYH Tyr165Cys and the XRCC1 Arg399Gln with the risk of childhood acute lymphoblastic leukemia (ALL). Our study included 97 children patients with ALL (mean age 5.4 ± 2.5) and 131 healthy children (mean age 6.2 ± 2.8) used as controls. Genetic polymorphisms in BER pathway genes were examined using PCR and restriction fragment length polymorphism (RFLP). We have demonstrated that the OGG1 Cys/Cys genotype increases the risk of ALL (OR 5.36) whereas the Ser/Ser genotype variant strongly reduces the risk of this cancer among Polish children (OR 0.45). Although we did not observe the differences in single nucleotide polymorphisms (SNPs) in MUTYH and XRCC1 genes between control group and children with ALL, we have shown that the combined genotypes of examined genes can modulate the risk of childhood ALL in Polish population. We found that the combined genotype Arg/Gln–Cys/Cys of XRCC1/OGG1 (OR 3.83) as well as the Cys/Cys–Tyr/Tyr of OGG1/MUTYH (OR 6.75) increases the risk of ALL. In contrast, the combined genotype Arg/Arg–Ser/Ser of XRCC1/OGG1 (OR 0.40) as well as the Ser/Ser–Tyr/Tyr of OGG1/MUTYH (OR 0.43) played a protective role against this malignant disease. In conclusion, we suggest that polymorphisms of BER genes may be used as an important predictive factor for acute lymphoblastic leukemia in children.     

The basis of prostaglandin synthesis in coral: molecular cloning and expression of a cyclooxygenase from the Arctic soft coral Gersemia fruticosa

In vertebrates, the synthesis of prostaglandin hormones is catalyzed by cyclooxygenase (COX)-1, a constitutively expressed enzyme with physiological functions, and COX-2, induced in inflammation and cancer. Prostaglandins have been detected in high concentrations in certain corals, and previous evidence suggested their biosynthesis through a lipoxygenase-allene oxide pathway. Here we describe the discovery of an ancestor of cyclooxygenases that is responsible for prostaglandin biosynthesis in coral. Using a homology-based polymerase chain reaction cloning strategy, the cDNA encoding a polypeptide with approximately 50% amino acid identity to both mammalian COX-1 and COX-2 was cloned and sequenced from the Arctic soft coral Gersemia fruticosa. Nearly all the amino acids essential for substrate binding and catalysis as determined in the mammalian enzymes are represented in coral COX: the arachidonate-binding Arg(120) and Tyr(355) are present, as are the heme-coordinating His(207) and His(388); the catalytic Tyr(385); and the target of aspirin attack, Ser(530). A key amino acid that determines the sensitivity to selective COX-2 inhibitors (Ile(523) in COX-1 and Val(523) in COX-2) is present in coral COX as isoleucine. The conserved Glu(524), implicated in the binding of certain COX inhibitors, is represented as alanine. Expression of the G. fruticosa cDNA afforded a functional cyclooxygenase that converted exogenous arachidonic acid to prostaglandins. The biosynthesis was inhibited by indomethacin, whereas the selective COX-2 inhibitor nimesulide was ineffective. We conclude that the cyclooxygenase occurs widely in the animal kingdom and that vertebrate COX-1 and COX-2 are evolutionary derivatives of the invertebrate precursor.     

3-(2-Methoxytetrahydrofuran-2-yl)pyrazoles: a novel class of potent, selective cyclooxygenase-2 (COX-2) inhibitors

A series of 3-(2-methoxytetrahydrofuran-2-yl)pyrazoles (4–10) was synthesized. The compounds were evaluated for their ability to inhibit cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2) activity in human whole blood (HWB). The compound, 5-(4-methanesulfonylphenyl)-3-(2-methoxytetrahydrofuran-2-yl)-1-p-tolyl-1H-pyrazole 5 showed potent and selective COX-2 inhibition (IC₅₀ for COX-1: >100 μM and COX-2: 1.2 μM).     

选择性co x 一2 抑制剂在胶质瘤放疗中的研究进展

环氧合酶（cyclooxygenase,COX）又名前列腺素内过氧化物合成酶,是前列腺素类似物合成的限速酶。COX-2是其诱导型酶。胶质瘤中COX-2的高表达被认为与肿瘤的侵袭性、预后相关。COX-2在胶质瘤的发生发展过程中发挥重要作用。选择性COX-2抑制剂通过直接和间接的作用机制而成为放射增敏剂。它们通过直接作用肿瘤细胞增强放射反应性,同时间接通过前列腺素影响肿瘤的血管形成抑制肿瘤生长。在体内和体外的研究表明选择性COX-2抑制剂可以增强胶质瘤对放射的反应性．降低恶性胶质瘤患者术后放射的必需照射剂量。而且在提高肿瘤放射敏感性的同时不增加对正常组织的放射损伤,甚至对正常组织有放射保护作用。因此,放疗联合选择性COX-2抑制剂可能成为胶质瘤治疗的新的有效途径。     

Comparative gastrointestinal toxicity of selective cyclooxygenase (COX-2) inhibitors

Cyclooxygenase (COX-2) inhibitors were developed with the hope that they will cause fewer gastrointestinal adverse effects. Ability of selective as well as nonselective COX inhibitors to alter ischemia-reperfusion induced damage of gastric mucosa and hapten-induced colitis in rats has been compared. Celecoxib (10, 20 and 40 mg/kg(-l)) was significantly more potent at aggravating ischemia-reperfusion injury as compared to nimesulide. Similarly, celecoxib was found to maximally potentiate TNBS-induced colitis, followed by nimesulide and indomethacin. Celecoxib at its highest dose produced maximum deep histological injury. This paradoxic ulcer and colitis aggravating effect of selective COX-2 inhibitors may be explained by suppression of protective prostaglandins generated as a consequence of COX-2 induction in inflammatory states.     

Characterization of the electrophile binding site and substrate binding mode of the 26-kDa glutathione S-transferase from Schistosoma japonicum

The 26-kDa glutathione S-transferase from Schistosoma japonicum (Sj26GST), a helminth worm that causes schistosomiasis, catalyzes the conjugation of glutathione with toxic secondary products of membrane lipid peroxidation. Crystal structures of Sj26GST in complex with glutathione sulfonate (Sj26GSTSLF), S-hexyl glutathione (Sj26GSTHEX), and S-2-iodobenzyl glutathione (Sj26GSTIBZ) allow characterization of the electrophile binding site (H site) of Sj26GST. The S-hexyl and S-2-iodobenzyl moieties of these product analogs bind in a pocket defined by side-chains from the beta1-alpha1 loop (Tyr7, Trp8, Ile10, Gly12, Leu13), helix alpha4 (Arg103, Tyr104, Ser107, Tyr111), and the C-terminal coil (Gln204, Gly205, Trp206, Gln207). Changes in the Ser107 and Gln204 dihedral angles make the H site more hydrophobic in the Sj26GSTHEX complex relative to the ligand-free structure. These structures, together with docking studies, indicate a possible binding mode of Sj26GST to its physiologic substrates 4-hydroxynon-2-enal (4HNE), trans-non-2-enal (NE), and ethacrynic acid (EA). In this binding mode, hydrogen bonds of Tyr111 and Gln207 to the carbonyl oxygen atoms of 4HNE, NE, and EA could orient the substrates and enhance their electrophilicity to promote conjugation with glutathione.     

Synthesis and biological evaluation of substituted 2-sulfonyl-phenyl-3-phenyl-indoles: a new series of selective COX-2 inhibitors

A new series of substituted 2-sulfonyphenyl-3-phenyl-indole derivatives were synthesized and evaluated for their ability to inhibit COX-2 and COX-1enzymes. Most of the compounds synthesized were found to be highly potent and selective inhibitors of COX-2. This work led to the discovery of 2-aminosulfonylphenyl-3-phenyl-indole 5a which possesses higher activity and selectivity for COX-2 than Celecoxib both in vitro and in vivo.