Recent progress in the synthesis of diclofenac based NSAIDs analogs/derivatives

Non-steroidal anti-inflammatory drugs (NSAIDs) are known for inhibition of cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2). Diclofenac and its analogs, having phenylacetic acid moiety, are important NSAIDs. In this review article, various methodologies developed after 90?s for the synthesis of various analogs/derivatives of diclofenac sodium have been discussed and summarized.     

Docking studies on NSAID/COX-2 isozyme complexes using Contact Statistics analysis

Summary The selective inhibition of COX-2 isozymes should lead to a new generation of NSAIDs with significantly reduced side effects; e.g. celecoxib (Celebrex^®) and rofecoxib (Vioxx^®). To obtain inhibitors with higher selectivity it has become essential to gain additional insight into the details of the interactions between COX isozymes and NSAIDs. Although X-ray structures of COX-2 complexed with a small number of ligands are available, experimental data are missing for two well-known selective COX-2 inhibitors (rofecoxib and nimesulide) and docking results reported are controversial. We use a combination of a traditional docking procedure with a new computational tool (Contact Statistics analysis) that identifies the best orientation among a number of solutions to shed some light on this topic.     

Development of energetic pharmacophore for the designing of 1,2,3,4-tetrahydropyrimidine derivatives as selective cyclooxygenase-2 inhibitors

We present here the Energetic pharmacophore model representing complementary features of the 1,2,3,4-tetrahydropyrimidine for selective cyclooxygenase-2 (COX-2) inhibition. For the development of pharmacophore hypothesis, a total of 43 previously reported compounds were docked on active site of COX-2 enzyme. The generated pharmacophore features were ranked using energetic terms of Glide XP docking for 1,2,3,4-tetrahydropyrimidine scaffold to optimize its structure requirement for COX-2 inhibition. The thirty new 4,5,6-triphenyl-1,2,3,4-tetrahydropyrimidine derivatives were synthesized and assessed for selective COX-2 inhibitory activity. Two compounds 4B1 and 4B11 were found to be potent and selective COX-2 inhibitors. The molecular docking studies revealed that the newly synthesized compounds can be docked into COX-2 binding site and also provide the molecular basis for their activity.     

Inhibitory effects of acetylmelodorinol, chrysin and polycarpol from Mitrella kentii on prostaglandin E₂ and Thromboxane B₂ production and platelet activating factor receptor binding

Acetylmelodorinol, chrysin and polycarpol, together with benzoic acid, benzoquinone and stigmasterol were isolated from the leaves of Mitrella kentii (Bl.) Miq. The compounds were evaluated for their ability to inhibit prostaglandin E? (PGE?) and thromboxane B? (TXB?) production in human whole blood using a radioimmunoassay technique. Their inhibitory effect on platelet activating factor (PAF) receptor binding to rabbit platelet was determined using 3H-PAF as a ligand. Among the compounds tested, chrysin showed a strong dose-dependent inhibitory activity on PGE(2) production (IC?? value of 25.5 μM), which might be due to direct inhibition of cyclooxygenase-2 (COX-2) enzymatic activity. Polycarpol, acetylmelodorinol and stigmasterol exhibited significant and concentration-dependent inhibitory effects on TXB? production with IC?? values of 15.6, 19.1 and 19.4 μM, respectively, suggesting that they strongly inhibited COX-1 activity. Polycarpol and acetylmelodorinol showed strong dose-dependent inhibitory effects on PAF receptor binding with IC?? values of 24.3 and 24.5 μM, respectively.     

二芳基取代-1,2,4-三唑类化合物的合成及其抗炎活性研究

以选择性环氧化酶-2(COX-2)抑制剂Celecoxib为先导,根据其构效关系和分子模拟研究结果,应用生物电子等排原理等药物设计方法,设计合成了19个结构全新的二芳基取代-1,2,4-三唑类衍生物,其结构经IR,¹HNMR,MS和元素分析确证.初步的药理试验结果表明,部分目标化合物具有一定的抗炎活性.     

Drug Design,Synthesis and Biological Evaluation of Heterocyclic Molecules as Anti-Inflammatory Agents

Non-steroidal anti-inflammatory drugs (NSAIDs) are generally utilized for numerous inflammatory ailments. The long-term utilization of NSAIDs prompts adverse reactions such as gastrointestinal ulceration, renal dysfunction and hepatotoxicity; however, selective COX-2 inhibitors prevent these adverse events. Various scientific approaches have been employed to identify safer COX-2 inhibitors, as in any case, a large portion of particular COX-2 inhibitors have been retracted from the market because of severe cardiovascular events. This study aimed to develop and synthesize a novel series of indomethacin analogues with potential anti-inflammatory properties and fewer side effects, wherein carboxylic acid moiety was substituted using DCC/DMAP coupling. This study incorporates the docking of various indomethacin analogues to detect the binding interactions with COX-2 protein (PDB ID: 3NT1). MD simulation was performed to measure the stability and flexibility of ligand–protein interactions at the atomic level, for which the top-scoring ligand–protein complex was selected. These compounds were evaluated in vitro for COX enzymes inhibition. Likewise, selected compounds were screened in vivo for anti-inflammatory potential using the carrageenan-induced rat paw oedema method and their ulcerogenic potential. The acute toxicity of compounds was also predicted using in silico tools. Most of the compounds exhibited the potent inhibition of both COX enzymes; however, 3e and 3c showed the most potent COX-2 inhibition having IC50 0.34 µM and 1.39 µM, respectively. These compounds also demonstrated potent anti-inflammatory potential without ulcerogenic liability. The biological evaluation revealed that the compound substituted with 4-nitrophenyl was most active.     

Synthesis of novel curcumin analogues and their evaluation as selective cyclooxygenase-1 (COX-1) inhibitors

Curcumin, a major yellow pigment and active component of turmeric, has been shown to possess anti-inflammatory and anti-cancer activities. Recent studies have indicated that cyclooxygenase-1 (COX-1) plays an important role in inflammation and carcinogenesis. In order to find more selective COX-1 inhibitors a series of novel curcumin derivatives was synthesized and evaluated for their ability to inhibit this enzyme using in vitro inhibition assays for COX-1 and COX-2 by measuring PGE(2) production. All curcumin analogues showed a higher rate of COX-1 inhibition. The most potent curcumin compounds were (1E,6E)-1,7-di-(2,3,4-trimethoxyphenyl)-1,6-heptadien-3,5-dione (4) (COX-1: IC(50) = 0.06 microM, COX-2: IC(50) > 100 microM, selectivity index>1666) and (1E,6E)-methyl 4-[7-(4-methoxycarbonyl)phenyl]-3,5-dioxo-1,6-heptadienyl]benzoate (6) (COX-1: IC(50) = 0.05 microM, COX-2: IC(50) > 100 microM, selectivity index > 2000). Curcumin analogues therefore represent a novel class of highly selective COX-1 inhibitors and promising candidates for in vivo studies.     

Synthesis and biological evaluation of novel sulfonanilide compounds as antiproliferative agents for breast cancer

Combinatorial chemistry approaches facilitate drug discovery processes and result in structural modifications of lead compounds that enhance pharmacological activity, improve pharmacokinetic properties, or reduce unwanted side effects. Epidemiological and animal model studies have suggested that nonsteroidal anti-inflammatory drugs (NSAIDs) can act as chemopreventive agents. The cyclooxygenase-2 (COX-2) inhibitor nimesulide shows anticancer effects in several cancer cell lines via COX-2-dependent and -independent mechanisms. The molecular structure of nimesulide was used as a starting scaffold to design novel sulfonanilide analogs and examine the structural features that contribute to this anticancer effect. A systematic combinatorial chemical approach was used to generate diversely substituted sulfonanilide derivatives that were tested for their effects on the proliferation of human breast cancer cells. Structure-function analysis indicated that the inhibition of cell growth by compounds derived from the novel sulfonanilides required a bulky terminal phenyl ring, a methanesulfonamide, and a hydrophobic carboxamide moiety.     

Free energy perturbation approach to the critical assessment of selective cyclooxygenase-2 inhibitors

The discovery of selective cyclooxygenase-2 (COX-2) inhibitors represents a major achievement of the efforts over the past few decades to develop therapeutic treatments for inflammation. To gain insights into designing new COX-2-selective inhibitors, we address the energetic and structural basis for the selective inhibition of COX isozymes by means of a combined computational protocol involving docking experiment, force field design for the heme prothetic group, and free energy perturbation (FEP) simulation. We consider both COX-2- and COX-1-selective inhibitors taking the V523I mutant of COX-2 to be a relevant structural model for COX-1 as confirmed by a variety of experimental and theoretical evidences. For all COX-2-selective inhibitors under consideration, we find that free energies of binding become less favorable as the receptor changes from COX-2 to COX-1, due to the weakening and/or loss of hydrogen bond and hydrophobic interactions that stabilize the inhibitors in the COX-2 active site. On the other hand, COX-1-selective oxicam inhibitors gain extra stabilization energy with the change of residue 523 from valine to isoleucine because of the formations of new hydrogen bonds in the enzyme-inhibitor complexes. The utility of the combined computational approach, as a valuable tool for in silico screening of COX-2-selective inhibitors, is further exemplified by identifying the physicochemical origins of the enantiospecific selective inhibition of COX-2 by -substituted indomethacin ethanolamide inhibitors.     

Activity-Guided Characterization of COX-2 Inhibitory Compounds in Waltheria indica L. Extracts

Inflammation is the body’s response to infection or tissue injury in order to restore and maintain homeostasis. Prostaglandin E2 (PGE-2) derived from arachidonic acid (AA), via up-regulation of cyclooxygenase-2 (COX-2), is a key mediator of inflammation and can also be induced by several other factors including stress, chromosomal aberration, or environmental factors. Targeting prostaglandin production by inhibiting COX-2 is hence relevant for the successful resolution of inflammation. Waltheria indica L. is a traditional medicinal plant whose extracts have demonstrated COX-2 inhibitory properties. However, the compounds responsible for the activity remained unknown. For the preparation of extracts with effective anti-inflammatory properties, characterization of these substances is vital. In this work, we aimed to address this issue by characterizing the substances responsible for the COX-2 inhibitory activity in the extracts and generating prediction models to quantify the COX-2 inhibitory activity without biological testing. For this purpose, an extract was separated into fractions by means of centrifugal partition chromatography (CPC). The inhibitory potential of the fractions and extracts against the COX-2 enzyme was determined using a fluorometric COX-2 inhibition assay. The characterizations of compounds in the fractions with the highest COX-2 inhibitory activity were conducted by high resolution mass spectrometry (HPLC-MS/MS). It was found that these fractions contain alpha-linolenic acid, linoleic acid and oleic acid, identified and reported for the first time in Waltheria indica leaf extracts. After analyzing their contents in different Waltheria indica extracts, it could be demonstrated that these fatty acids are responsible for up to 41% of the COX-2 inhibition observed with Waltheria indica extract. Additional quantification of secondary metabolites in the extract fractions revealed that substances from the group of steroidal saponins and triterpenoid saponins also contribute to the COX-2 inhibitory activity. Based on the content of compounds contributing to COX-2 inhibition, two mathematical models were successfully developed, both of which had a root mean square error (RMSE) = 1.6% COX-2 inhibitory activity, demonstrating a high correspondence between predicted versus observed values. The results of the predictive models further suggested that the compounds contribute to COX-2 inhibition in the order linoleic acid > alpha linolenic acid > steroidal saponins > triterpenoid saponins. The characterization of substances contributing to COX-2 inhibition in this study enables a more targeted development of extraction processes to obtain Waltheria indica extracts with superior anti-inflammatory properties.     

Sequential injection system for phospholipase A2 activity evaluation: Studies on liposomes using an environment-sensitive fluorescent probe

This work reports the development of an automatic methodology based on the use of 1-anilinonaphthalene-8-sulfonate (ANS) as an interfacial fluorescent probe for detecting the hydrophobic environment shift around the probe, caused by the hydrolytic action of PLA₂ on the liposomes. The implementation of this reaction in a sequential injection analysis (SIA) system along with the use of the mixing chambers permitted the evaluation of PLA₂ activity and assessment of the inhibitory effect of the non-steroidal anti-inflammatory drugs (NSAIDs) on PLA₂ activity.Several studies were performed with the aim of establishing the appropriate flow system configuration: the liposome substrate; PLA₂ and ANS optimum concentrations and incubation times before and after the enzyme addition. Based on these studies, the optimum reaction conditions were selected. It was shown that PLA₂ is effectively inhibited by the NSAIDs tested (meloxicam, tolmetin and ibuprofen) and by the α-lipoic acid, used as a positive control.Results obtained from the flow system are in agreement with those provided by the comparison batch procedures. The proposed methodology is in fact more efficient and rapid than the comparison batch experiments, enabling the exact timing of fluidic manipulations and precise control of the reaction conditions.     

COX抑制剂——氟比洛芬衍生物的作用方式及选择性研究

用DOCK4.0程序搜索氟比洛芬衍生物与环氧合酶结合的构象。用Cscore综合评 分体系确定最佳构象，复合物经分子力学优化后，发现衍生物在COX-1中的取向和 位置与X射线衍射测犁晶体复合物中氟比洛芬作用方式相同；衍生物在COX-2中也有 与氟比洛芬类似的结合方式。衍生物对COX-2/COX-1 的选择掏性与衍生物作用于两 种酶的结合自由能之差有较好的相关性。相关系数     

A new cyclooxygenase (COX) inhibitory pterocarpan from Indigofera aspalathoides: structure elucidation and determination of binding orientations in the active sites of the enzyme by molecular docking

A new compound indigocarpan (1) and the known compound mucronulatol (2) were isolated from chloroform extracts of Indigofera aspalathoides. Their structures were established by spectroscopic methods, including single-crystal X-ray analysis (in the case of 1). The isolates were evaluated for cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2) inhibitory activities and antioxidant properties. The new compound 1 showed significant COX-1 inhibition (IC₅₀ 30.5 μM) and its in vivo anti-inflammatory activity was found to be comparable to that of ibuprofen. Molecular docking studies revealed the binding orientations of 1 in the active sites of COX-1 and COX-2.     

Structure-based QSAR study on differential inhibition of human prostaglandin endoperoxide H synthase-2 (COX-2) by nonsteroidal anti-inflammatory drugs

The prostaglandin-endoperoxide H synthase-1 (PGHS-1) and prostaglandin-endoperoxide H synthase-2 (PGHS-2) are the targets of nonsteroidal anti-inflammatory drugs (NSAIDs).It appears that the high degree of selectivity for inhibition of PGHS-2 shown by certain compounds is the result of two mechanisms (time-dependent, time-independent inhibition), by which they interact with each isoform. Molecular models of the complexes formed by indomethacin, sulindac, fenamates, 2-phenylpropionic acids and selective cyclooxygenase-2 (COX-2) inhibitors with the cyclooxygenase active site of human PGHS-2 have been built, paying particular attention to water molecules that participate in the hydrogen-bonding network at the polar active site entrance. The stability of the complexes has been assessed by molecular dynamics simulations and interaction energy decomposition analysis, and their biological significance has been discussed in light of available X-ray crystallographic and kinetic results. The selective PGHS-2 inhibitors exploit the extra space of a side-pocket in the active site of PGHS-2 that is not found in PGHS-1. The results suggest that active site hydration together with residues Tyr³⁵⁵, Glu⁵²⁴, Arg¹²⁰ and Arg⁵¹³ are crucial to understand the time-dependent inhibition mechanism. A marked relationship between the isoform selectivity and tightly interactions with residues into the side pocket bordered by Val⁵²³ is also found.     

Infrared (810 nm) low-level laser therapy in rat achilles tendinitis: a consistent alternative to drugs

Nonsteroidal anti-inflammatory drugs (NSAIDs) are widely used and can reduce musculoskeletal pain in spite of the cost of adverse reactions like gastrointestinal ulcers or cardiovascular events. The current study investigates if a safer treatment such as low-level laser therapy (LLLT) could reduce tendinitis inflammation, and whether a possible pathway could be through inhibition of either of the two-cyclooxygenase (COX) isoforms in inflammation. Wistar rats (six animals per group) were injected with saline (control) or collagenase in their Achilles tendons. Then, we treated them with three different doses of IR LLLT (810 nm; 100 mW; 10 s, 30 s and 60 s; 3.57 W cm(-2); 1 J, 3 J, 6 J) at the sites of the injections, or intramuscular diclofenac, a nonselective COX inhibitor/NSAID. We found that LLLT dose of 3 J significantly reduced inflammation through less COX-2-derived gene expression and PGE(2) production, and less edema formation compared to nonirradiated controls. Diclofenac controls exhibited significantly lower PGE(2) cytokine levels at 6 h than collagenase control, but COX isoform 1-derived gene expression and cytokine PGE(2) levels were not affected by treatments. As LLLT seems to act on inflammation through a selective inhibition of the COX-2 isoform in collagenase-induced tendinitis, LLLT may have potential to become a new and safer nondrug alternative to coxibs.     

Synthesis,anti-inflammatory activities and docking studies of amide derivatives of meclofenamic acid

NSAIDs constitute a heterogeneous class of pharmacological agents widely prescribed for the treatment of inflammation, pain and edema, as well as osteoarthritis, rheumatoid arthritis and musculoskeletal disorders. This class of drugs has proved efficacious on account of their analgesic, anti-pyretic and anti-inflammatory activities, but gastrointestinal toxicity exists as the biggest problem associated with their chronic use. Many attempts have been made to structurally modify conventional NSAIDs as selective COX-2 inhibitors based on the old and still prevalent common belief that selective inhibition of COX-2 would provide safer NSAIDs. The present work thus focused on the synthesis of amide derivatives of one of the conventional non-selective NSAID, meclofenamic acid utilizing the one pot procedure involving a selective agent, bis (2-oxo-3-oxazolidinyl) phosphonic chloride. The synthesized compounds were tested for their in vivo inflammatory activity using carrageenan rat paw edema assay, and were subsequently docked on COX-2 PDB code 4COX to have better insights into their mechanism of action. The amide derivative with N-4-methoxybenzyl moiety (TSN4) proved to have anti-inflammatory potential (72.8%) better than meclofenamic acid (56.75%). This compound also docked with the highest dock score among the synthesized compounds and was found to have both hydrogen bonding with Arg120 and Tyr355 and hydrophobic interactions with Val349, Leu352, Ser353, Tyr385, Trp387, Met522, Val523, Ala527 and Ser530. N-4-methoxybenzyl amide derivative (TSN4) followed by benzyl amide derivative (TSN1) of meclofenamic acid were identified as potential anti-inflammatory compounds in both in vivo and in silico studies.     

Phytochemical and Biological Activity Studies on Nasturtium officinale (Watercress) Microshoot Cultures Grown in RITA® Temporary Immersion Systems

The main compounds in both extracts were gluconasturtiin, 4-methoxyglucobrassicin and rutoside, the amounts of which were, respectively, determined as 182.93, 58.86 and 23.24 mg/100 g dry weight (DW) in biomass extracts and 640.94, 23.47 and 7.20 mg/100 g DW in plant herb extracts. The antioxidant potential of all the studied extracts evaluated using CUPRAC (CUPric Reducing Antioxidant Activity), FRAP (Ferric Reducing Ability of Plasma), and DPPH (1,1-diphenyl-2-picrylhydrazyl) assays was comparable. The anti-inflammatory activity of the extracts was tested based on the inhibition of 15-lipoxygenase, cyclooxygenase-1, cyclooxygenase-2 (COX-2), and phospholipase A₂. The results demonstrate significantly higher inhibition of COX-2 for in vitro cultured biomass compared with the herb extracts (75.4 and 41.1%, respectively). Moreover, all the studied extracts showed almost similar antibacterial and antifungal potential. Based on these findings, and due to the fact that the growth of in vitro microshoots is independent of environmental conditions and unaffected by environmental pollution, we propose that biomass that can be rapidly grown in RITA^® bioreactors can serve as an alternative source of bioactive compounds with valuable biological properties.