Amino acid derivatives of 2-Mercaptobenzimidazoles suppress cytokines at the site of inflammation and block gastric H+/K+ ATPase.

Routinely used anti-inflammatory drugs are associated with off-target effects such as cyclooxygenase (COX)-1 inhibition and gastric ulcers. The aim of this study is to examine the anti-inflammatory potential and gastroprotective effects of synthetic amino acid derivatives of 2-mercaptobenzimidazole (MBAA1, MBAA2, MBAA3, MBAA4 and MBAA5). The results showed that compound MBAA5 possess a potential anti-inflammatory action by inhibition of 15-LOX and COX-2. MBAA5 also attenuated the pro-inflammatory cytokines and mediators (TNF-α, IL-1ß and COX-2) in rat hind paw in carrageenan-induced inflammatory model of rat. 2-mercaptobenzimidazole derivative, MBAA5 also inhibited gastric H+/K+ ATPase and demonstrated a better selectivity index for COX-2 (SI 27.17) in comparison to celecoxib (SI 41.43). Molecular docking studies predicted the binding interactions of the synthesized compounds with retrieved target proteins of H+/K+ ATPase, COX-1, COX-2, and 15-LOX. The results of in silico and molecular docking analysis of amino acid derivatives of 2-mercaptobenzimidazoles further explained their pharmacological activities. Moreover, these compounds presented better antimicrobial activity against three clinical isolates of Helicobacter pylori. Together, our findings suggested that these synthetic 2-mercaptobenzimidazole derivatives are safer therapeutic candidates for inflammation.

Puerarin Inhibits Endothelium-Dependent Contractions in Mouse Carotid Arteries.

BACKGROUND Many bioactive ingredients of medicinal plants are known to produce vaso-protective benefits. Puerarin is one of the major isoflavone glucosides found in the root of kudzu vine and it exerts an anti-inflammatory effect and many other pharmacological actions. However, the mechanism underlying the vascular effect of puerarin is incompletely understood. Therefore, the present study aims to examine how puerarin reduces endothelium-dependent contractions (EDCs) in mouse arteries. MATERIAL AND METHODS EDCs were evoked by acetylcholine (ACh) in isolated mouse carotid arteries with intact endothelium pretreated with Nω-NO2-L-Arg-OMe (L-NAME). The arteries were pretreated with puerarin and other pharmacological inhibitors before the addition of cumulative concentrations of ACh. The concentration of several prostaglandins (PGs) was measured by high performance liquid chromatography-coupled spectrometry (HPLC-MS). RESULTS EDCs induced by ACh only presented in endothelium-intact arteries pretreated by L-NAME and EDCs were prevented by the treatment with cyclooxygenase (COX) inhibitor indomethacin (3 µmol/L) or thromboxane prostanoid receptor (TP receptor) antagonist S18886 (30 nmol/L). Acute 40-minute treatment with puerarin reduced EDCs in a concentration-dependent manner without affecting U46619-induced contraction. However, treatment with puerarin did not inhibit ACh-induced production of prostaglandins (PGs) in endothelium-intact arteries. CONCLUSIONS The present results show that puerarin is able to suppress EDCs in mouse carotid arteries, independent of inhibition of TP receptor or COX2-derived PGs.

Naproxen attenuates osteoarthritis progression through inhibiting the expression of prostaglandinl-endoperoxide synthase 1.

OBJECTIVE: This study aims to test the effect of naproxen treatment and the biological target of naproxen for treating osteoarthritis (OA). METHODS: Differentially expressed genes (DEGs) in OA synovial tissues and normal counterparts were analyzed by messenger RNA microarray analysis. R package (weighted gene coexpression network analysis) was used to divide DEGs into several modules and determine the hub genes in each module. The expression level of prostaglandin-endoperoxide synthase 1 ( PTGS1) in OA synovial cells and tissues was verified by a quantitative real-time polymerase chain reaction and western blot. Transwell assay evaluated the numbers of cell migration and invasion. Furthermore, Safranin O and fast green staining and hematoxylin and eosin staining were performed on joints from anterior cruciate ligament transection mice. RESULTS: Microarray analysis determined PTGS1 was the hub gene in the black module, which was overexpressed in OA synovial cells and tissues compared with normal synovial cells. OA synovial cells transfected with sh-PTGS1 showed downregulation of PTGS1. After treatment with naproxen, the expression of PTGS1 sharply decreased in the OA group. The migration and invasion of OA synovial cells increased, whereas the cell apoptosis rate decreased when PTGS1 was overexpressed. However, the cell migration and invasion decreased, whereas cells apoptosis increased when it was treated with naproxen. Naproxen could also influence the expression level of six OA-related genes: LUBRICIN, matrix metalloproteinase 13 (MMP-13), cyclooxygenase-2 (COX-2), ACAN, COL2A1, and COL1A1. CONCLUSION: We validated that naproxen could suppress the expression of PTGS1 in synovial cells. Moreover, naproxen could inhibit the migration/invasion ability of OA synoviocytes and promote the apoptosis rate OA synoviocytes.

Optimization of Methionyl tRNA-Synthetase Inhibitors for Treatment of Cryptosporidium Infection.

Cryptosporidiosis is one of the leading causes of moderate to severe diarrhea in children in low-resource settings. The therapeutic options for cryptosporidiosis are limited to one drug, nitazoxanide, which unfortunately has poor activity in the most needy populations of malnourished children and HIV-infected persons. We describe here the discovery and early optimization of a class of imidazopyridine-containing compounds with potential for treating Cryptosporidium infections. The compounds target the Cryptosporidium methionyl-tRNA synthetase (MetRS), an enzyme that is essential for protein synthesis. The most potent compounds inhibited the enzyme with Ki values in the low picomolar range. Cryptosporidium cells in culture were potently inhibited with 50% effective concentrations as low as 7 nM and >1,000-fold selectivity over mammalian cells. A parasite persistence assay indicates that the compounds act by a parasiticidal mechanism. Several compounds were demonstrated to control infection in two murine models of cryptosporidiosis without evidence of toxicity. Pharmacological and physicochemical characteristics of compounds were investigated to determine properties that were associated with higher efficacy. The results indicate that MetRS inhibitors are excellent candidates for development for anticryptosporidiosis therapy.

Synthesis, molecular docking, and pharmacological evaluation of N-(2-(3,5-dimethoxyphenyl)benzoxazole-5-yl)benzamide derivatives as selective COX-2 inhibitors and anti-inflammatory agents.

A series of N-(2-(3,5-dimethoxyphenyl)benzoxazole-5-yl)benzamide derivatives (3am) was synthesized and evaluated for their in vitro inhibitory activity against COX-1 and COX-2. The compounds with considerable in vitro activity (IC50 < 1 µM) were evaluated in vivo for their anti-inflammatory potential by the carrageenan-induced rat paw edema method. Out of 13 newly synthesized compounds, 3a, 3b, 3d, 3g, 3j, and 3k were found to be the most potent COX-2 inhibitors in the in vitro enzymatic assay, with IC50 values in the range of 0.06-0.71 µM. The in vivo anti-inflammatory activity of these six compounds (3a, 3b, 3d, 3g, 3j, and 3k) was assessed by the carrageenan-induced rat paw edema method. Compounds 3d (84.09%), 3g (79.54%), and 3a (70.45%) demonstrated significant anti-inflammatory activity compared to the standard drug ibuprofen (65.90%) and were also found to be safer than ibuprofen, by ulcerogenic studies. A docking study was done using the crystal structure of human COX-2, to understand the binding mechanism of these inhibitors to the active site of COX-2.

Anti-inflammatory activity of anti-hyperlipidemic drug, fenofibrate, and its phase-I metabolite fenofibric acid: in silico, in vitro, and in vivo studies.

Fenofibrate, an anti-hyperlipidemic drug and its phase-I biotransformed metabolite fenofibric acid, was studied for COX-1 (PDB ID: 3N8Y) and COX-2 (PDB ID: 1PXX) inhibition potentials in silico and in vitro for their effects on human recombinant COX-2 enzyme isolated from a Baculovirus expression system in sf21 cells (EC 1.14.99.1) using a conventional spectrophotometric assay. Furthermore, the compounds were also screened for their anti-inflammatory potentials in vivo using carrageenan-induced paw oedema method in Wistar rats. The test compounds fenofibric acid, fenofibrate, and the standard drug diclofenac exhibited binding energies of - 9.0, - 7.2, and - 8.0 kcal mol-1, respectively, against COX-2 and - 7.2, - 7.0, and - 6.5 kcal mol-1, respectively, against COX-1. In in vitro studies, both the test compounds inhibited COX-2 enzyme activity. Fenofibric acid showed an IC50 value of 48 nM followed by fenofibrate (82 nM), while diclofenac showed an IC50 value of 58 nM. Furthermore, under in vivo conditions in carrageenan-induced paw oedema rodent model, fenofibric acid exhibited relatively potent anti-inflammatory activity compared with fenofibrate. Hence, we conclude that fenofibric acid and fenofibrate are not only anti-hyperlipidemic but also shows potent anti-inflammatory activity, which may have an additional impact in the treatment of diabetic complications, viz., hyperlipidemia and inflammation leading to atherosclerosis.

Aspirin inhibits the production of proangiogenic 15(S)-HETE by platelet cyclooxygenase-1.

Regular consumption of low-dose aspirin reduces the occurrence of colorectal, esophageal, stomach, and gastrointestinal cancers. The underlying mechanism is unknown but may be linked to inhibition of angiogenesis. Because the effective doses of aspirin are consistent with the inhibition of cyclooxygenase-1 in platelets, we used liquid chromatography with tandem mass spectrometry analyses and immunoassays of human platelet releasates coupled with angiogenesis assays to search for the mediators of these effects. Blood or platelet-rich plasma from healthy volunteers stimulated with platelet activators produced a broad range of eicosanoids. Notably, preincubation of platelets with aspirin, but not with a P2Y12 receptor antagonist, caused a marked reduction in the production of 11-hydroxyeicosatetraenoic acid (HETE) and 15(S)-HETE, in addition to prostanoids such as thromboxane A2 Releasates from activated platelets caused cell migration and tube formation in cultured human endothelial cells and stimulated the sprouting of rat aortic rings in culture. These proangiogenic effects were absent when platelets were treated with aspirin but returned by coincubation with exogenous 15(S)-HETE. These results reveal 15(S)-HETE as a major platelet cyclooxygenase-1 product with strong proangiogenic effects. Thus, 15(S)-HETE represents a potential target for the development of novel antiangiogenic therapeutics, and blockade of its production may provide a mechanism for the anticancer effects of aspirin.-Rauzi, F., Kirkby, N. S., Edin, M. L., Whiteford, J. Zeldin, D. C., Mitchell, J. A., Warner, T. D. Aspirin inhibits the production of proangiogenic 15(S)-HETE by platelet cyclooxygenase-1.

Tailoring naringenin conjugates with amplified and triple antiplatelet activity profile: Rational design, synthesis, human plasma stability and in vitro evaluation.

BACKGROUND: The current standard-of-care antiplatelet therapy in cardiovascular disease patients is consisted of cyclooxygenase-1 (COX-1) inhibitor aspirin, along with a platelet receptor P2Y12 antagonist. Recently, the triple antiplatelet therapy with aspirin, a P2Y12 receptor antagonist and a protease activated receptor-1 (PAR-1) antagonist, has been suggested for the secondary prevention of atherothrombotic events, however presented an increased risk of bleeding. Therefore, the quest for novel antiplatelet agents simultaneously targeting the three pathways with improved efficacy/safety profile is of immense importance. Flavonoids as pre-validated ligands for numerous targets could serve as scaffolds targeting the three platelet activation pathways. METHODS: Computational methods, Ultra High Performance Liquid Chromatography-Tandem Mass Spectrometry (UHPLC-MS/MS) plasma stability and in vitro platelet aggregation experiments were used to establish the antiplatelet activity of the flavonoid naringenin and its conjugates. RESULTS: In silico studies indicated that naringenin could bear a potent triple antiplatelet activity by inhibiting different platelet aggregation mechanisms. However, we found that in human platelets naringenin has diminished activity. We rationally designed and synthesized different naringenin conjugates aiming to amplify the antiplatelet activity of the parent compound. UHPLC-MS/MS revealed a slow degradation rate for a docosahexaenoic acid (DHA) - naringenin conjugate in human plasma. The antiplatelet profile of the new analogues was evaluated against in vitro platelet aggregation induced by several platelet agonists. CONCLUSIONS: The DHA - naringenin hybrid presented triple antiplatelet activity simultaneously targeting PAR-1, P2Y12 and COX-1 platelet activation pathways. GENERAL SIGNIFICANCE: Natural products could offer a rich source for novel bioactives as a powerful alternative to the current combinatorial use of three different antiplatelet drugs.

Synthesis and Biological Evaluation of New Diarylpyrazole and Triarylimidazoline Derivatives as Selective COX-2 Inhibitors.

New series of diarylpyrazoles 8a-f and triarylimidazoline-5-ones 11a-g were synthesized and evaluated for their in vitro cyclooxygenase-1 (COX-1) and COX-2 inhibitory activity and in vivo anti-inflammatory activity. The synthesized compounds showed good selectivity for COX-2; compounds 8a, 8d, 8f, 11a, and 11c exhibited the highest COX-2 selectivity indexes (SI = 4.77-5.43) compared to the reference drug celecoxib (SI = 7.8). All compounds showed good in vivo anti-inflammatory activity, especially compounds 8a, 8f, 11c, and 11d, which also showed some similarities to the time interval pattern of celecoxib at all different time intervals (1, 3, and 6 h).

Tonic Local Brain Blood Flow Control by Astrocytes Independent of Phasic Neurovascular Coupling.

According to the current model of neurovascular coupling, blood flow is controlled regionally through phasic changes in the activity of neurons and astrocytes that signal to alter arteriole diameter. Absent in this model, however, is how brain blood flow is tonically regulated independent of regional changes in activity. This is important because a large fraction of brain blood flow is required to maintain basal metabolic needs. Using two-photon fluorescence imaging combined with patch-clamp in acute rat brain slices of sensory-motor cortex, we demonstrate that reducing resting Ca(2+) in astrocytes with intracellular BAPTA causes vasoconstriction in adjacent arterioles. BAPTA-induced vasoconstriction was eliminated by a general COX blocker and the effect is mimicked by a COX-1, but not COX-2, antagonist, suggesting that astrocytes provide tonic, steady-state vasodilation by releasing prostaglandin messengers. Tonic vasodilation was insensitive to TTX, as well as a variety of synaptic and extrasynaptic receptor antagonists, indicating that the phenomenon operates largely independent of neural activity. Using in vivo two-photon fluorescence imaging of the barrel cortex in fully awake mice, we reveal that acute COX-1 inhibition reduces resting arteriole diameter but fails to affect vasodilation in response to vibrissae stimulation. Our findings demonstrate that astrocytes provide tonic regulation of arterioles using resting intracellular Ca(2+) in a manner that is independent of phasic, neuronal-evoked vasodilation. Significance statement: The brain requires both phasic and tonic regulation of its blood supply to service energy needs over various temporal windows. While many mechanisms have been described for phasic blood flow regulation, how the brain accomplishes tonic control is largely unknown. Here we describe a way in which astrocytes contribute to the management of basal brain blood flow by providing steady-state vasodilation to arterioles via resting astrocyte Ca(2+) and the continuous release of prostaglandin messengers. This phenomenon may be important for understanding the declines in basal brain blood flow that occur in aging and dementia, as well as for the interpretation of fMRI data.

Beneficial effects of vitamin C treatment on pregnant rats exposed to formaldehyde: Reversal of immunosuppression in the offspring.

Inhalation of formaldehyde (FA) during the pregnancy induces oxidative stress in the uterus, and here we hypothesized that this mechanism may be responsible for the impaired immune response detected in the offspring. In order to investigate the protective effects of Vitamin C on the oxidative stress induced by FA in the uterine microenvironment, pregnant Wistar rats were treated with vitamin C (150mg/kg, gavage) or vehicle (distilled water, gavage) 1h before FA exposure (0.92mg/m(3), 1h/day, 5days/week), for 21days, and the 30days old offspring were submitted to LPS injection (Salmonella abortus equi, 5mg/kg, i.p.). The enhanced gene expression of iNOS, COX-1 and COX-2 and decreased gene expression of SOD-2 in the uterus of FA exposed mothers was rescued by Vit C treatment. Moreover, vitamin C rescued the impaired immune response elicited by LPS in the offspring from FA exposed mothers, by increasing the number of blood and bone marrow leukocytes, and augmenting gene expression of IL-6 and reducing mRNA levels of IL-10 and IFN in the lungs. Vitamin C treatment did not rescue the impaired TLR4-NF-kB pathway in the lung of the offspring, suggesting that FA-induced uterine oxidative stress affects other inflammatory pathways activated by LPS in the offspring. Together, data obtained here confirm our hypothesis that FA-induced oxidative stress in the uterine microenvironment modifies the programming mechanisms of the immune defenses of offspring, leading to an impaired host defense.

Synthesis, anti-inflammatory, analgesic, COX-1/2 inhibition activities and molecular docking study of pyrazoline derivatives.

Design, synthesis and pharmacological activities of a group of 1,3,5-trisubstituted pyrazolines were reported. The chemical structures of the synthesized compounds have been assigned on the basis of IR, MS, (1)H NMR, and (13)C NMR spectral analyses. The synthesized 1,3,5-trisubstituted pyrazoline derivatives were evaluated in vivo for anti-inflammatory, analgesic activities and in vitro for COX-1/2 inhibition assay. Among the tested compounds, derivatives 4h, 6e, 7a, 7e, and 9 showed more potent anti-inflammatory and analgesic activities than the reference drug celecoxib. On the basis of their higher activities in the in vivo studies compared with celecoxib, the five compounds 4h, 6e, 7a, 7e and 9 were selected to test their inhibitory activities against ovine COX-1/2 using an in vitro cyclooxygenase inhibition assay. Docking study of compounds 7a, 7e and 9 into the COX-2 binding site revealed a similar binding mode to SC-558, a selective COX-2 inhibitor.

Topical Anti-Inflammatory and Analgesic Effects of Multiple Applications of S(+)-Flurbiprofen Plaster (SFPP) in a Rat Adjuvant-Induced Arthritis Model.

Preclinical Research The aim of this study was to evaluate the efficacy of multiple applications of S(+)-flurbiprofen plaster (SFPP), a novel Nonsteroidal anti-inflammatory drug (NSAID) patch, for the alleviation of inflammatory pain and edema in rat adjuvant-induced arthritis (AIA) model as compared to other NSAID patches. The AIA model was induced by the injection of Mycobacterium butyricum and rats were treated with a patch (1.0 cm × 0.88 cm) containing each NSAID (SFP, ketoprofen, loxoprofen, diclofenac, felbinac, flurbiprofen, or indomethacin) applied to the paw for 6 h per day for 5 days. The pain threshold was evaluated using a flexion test of the ankle joint, and the inflamed paw edema was evaluated using a plethysmometer. cyclooxygenase (COX)-1 and COX-2 inhibition was evaluated using human recombinant proteins. Multiple applications of SFPP exerted a significant analgesic effect from the first day of application as compared to the other NSAID patches. In terms of paw edema, SFPP decreased edema from the second day after application, Multiple applications of SFPP were superior to those of other NSAID patches, in terms of the analgesic effect with multiple applications. These results suggest that SFPP may be a beneficial patch for providing analgesic and anti-inflammatory effects clinically. Drug Dev Res 77 : 206-211, 2016. © 2016 The Authors Drug Development Research Published by Wiley Periodicals, Inc.

Sulindac reversal of 15-PGDH-mediated resistance to colon tumor chemoprevention with NSAIDs.

Non-steroidal anti-inflammatory drugs prevent colorectal cancer by inhibiting cyclooxygenase (COX) enzymes that synthesize tumor-promoting prostaglandins. 15-hydroxyprostaglandin dehydrogenase (15-PGDH) is a tumor suppressor that degrades tumor-promoting prostaglandins. Murine knockout of 15-PGDH increases susceptibility to azoxymethane-induced colon tumors. It also renders these mice resistant to celecoxib, a selective inhibitor of inducible COX-2 during colon neoplasia. Similarly, humans with low colonic 15-PGDH are also resistant to colon adenoma prevention with celecoxib. Here, we used aspirin and sulindac, which inhibit both COX-1 and COX-2, in order to determine if these broader COX inhibitors can prevent colon tumors in 15-PGDH knockout (KO) mice. Unlike celecoxib, sulindac proved highly effective in colon tumor prevention of 15-PGDH KO mice. Significantly, however, aspirin demonstrated no effect on colon tumor incidence in either 15-PGDH wild-type or KO mice, despite a comparable reduction in colonic mucosal Prostaglandin E2 (PGE2) levels by both sulindac and aspirin. Notably, colon tumor prevention activity by sulindac was accompanied by a marked induction of lymphoid aggregates and proximal colonic inflammatory mass lesions, a side effect seen to a lesser degree with celecoxib, but not with aspirin. These findings suggest that sulindac may be the most effective agent for colon cancer prevention in humans with low 15-PGDH, but its use may also be associated with inflammatory lesions in the colon.

Combined Therapy with Rheum tanguticum Polysaccharide and Low-dose 5-ASA Ameliorates TNBS-Induced Colitis in Rats by Suppression of NF-κB.

The most common conventional therapy for inflammatory bowel disease in clinical practice involves the use of nonsteroidal anti-inflammatory drugs, such as 5-amino salicylic acid. However, a high dose of 5-amino salicylic acid may bring about severe side effects. Chinese people have used Rheum tanguticum as a folk remedy for gastrointestinal disease for two thousand years. Our group has isolated R. tanguticum polysaccharide 1 from R. tanguticum and verified that it can attenuate 2,4,6-trinitrobenzene sulfonic acid-induced colitis in murines/rats. The present study aims to evaluate whether the addition of R. tanguticum polysaccharide 1 can improve efficacy and limit subsequent side effects of conventional treatment (5-amino salicylic acid) in rats with 2,4,6-trinitrobenzene sulfonic acid-induced colitis. Sixty Sprague-Dawley male rats were randomized into five groups and treated with (1) saline (saline, 0.2 mL/day × 5, p. o.), (2) 2,4,6-trinitrobenzene sulfonic acid alone (saline, 0.2 mL/day × 5, p. o.), (3) 2,4,6-trinitrobenzene sulfonic acid + 5-amino salicylic acid (5-amino salicylic acid, 75 mg/kg/day × 5, p.o), (4) 2,4,6-trinitrobenzene sulfonic acid + R. tanguticum polysaccharide 1 (R. tanguticum polysaccharide 1, 200 mg/kg/day × 5, p. o.), and (5) 2,4,6-trinitrobenzene sulfonic acid + 5-amino salicylic acid + R. tanguticum polysaccharide 1 (5-amino salicylic acid, 25 mg/kg/day × 5, p.o; R. tanguticum polysaccharide 1, 200 mg/kg/day × 5, p. o.). All the rats were sacrificed on the 6th day after treatment using an overdose of anesthesia. A histological assessment was performed using semiquantitative scores; nuclear factor-kappa B and tumor necrosis factor-α were measured with Western blot, cyclooxygenase 1 and cyclooxygenase 2 protein expressions were investigated by RT-polymerase chain reaction, and prostoglandin E2 and inducible nitric oxide synthase productions were investigated by ELISA. The extent and severity of histological signs were attenuated significantly in the 2,4,6-trinitrobenzene sulfonic acid + 5-amino salicylic acid + R. tanguticum polysaccharide 1 group. Treatment with R. tanguticum polysaccharide 1 plus 5-amino salicylic acid markedly decreased nuclear factor-kappa Bp65 and tumor necrosis factor-α protein expressions. R. tanguticum polysaccharide 1 and 5-amino salicylic acid had no effect on cyclooxygenase 1 protein expression, but inhibited the overexpression of the cyclooxygenase 2 protein. After treatment with 5-amino salicylic acid and R. tanguticum polysaccharide 1, the prostoglandin E2 level increased significantly and the inducible nitric oxide synthase level decreased considerably in the 2,4,6-trinitrobenzene sulfonic acid + 5-amino salicylic acid + R. tanguticum polysaccharide 1 group compared with the 2,4,6-trinitrobenzene sulfonic acid alone group. These results demonstrate that combined therapy with R. tanguticum polysaccharide 1 and low-dose 5-amino salicylic acid had more favorable effects on 2,4,6-trinitrobenzene sulfonic acid-induced colitis in rats, and its effects may be associated with inhibiting nuclear factor-kappa Bp65 protein expression and tumor necrosis factor-α production, resulting in a decrease of cyclooxygenase 2 and inducible nitric oxide synthase protein expressions.

Synthesis and antiplatelet activity of antithrombotic thiourea compounds: biological and structure-activity relationship studies.

The incidence of hematological disorders has increased steadily in Western countries despite the advances in drug development. The high expression of the multi-resistance protein 4 in patients with transitory aspirin resistance, points to the importance of finding new molecules, including those that are not affected by these proteins. In this work, we describe the synthesis and biological evaluation of a series of N,N'-disubstituted thioureas derivatives using in vitro and in silico approaches. New designed compounds inhibit the arachidonic acid pathway in human platelets. The most active thioureas (compounds 3d, 3i, 3m and 3p) displayed IC50 values ranging from 29 to 84 µM with direct influence over in vitro PGE2 and TXA2 formation. In silico evaluation of these compounds suggests that direct blockage of the tyrosyl-radical at the COX-1 active site is achieved by strong hydrophobic contacts as well as electrostatic interactions. A low toxicity profile of this series was observed through hemolytic, genotoxic and mutagenic assays. The most active thioureas were able to reduce both PGE2 and TXB2 production in human platelets, suggesting a direct inhibition of COX-1. These results reinforce their promising profile as lead antiplatelet agents for further in vivo experimental investigations.

Drug resistance and pseudoresistance: an unintended consequence of enteric coating aspirin.

BACKGROUND: Low dose aspirin reduces the secondary incidence of myocardial infarction and stroke. Drug resistance to aspirin might result in treatment failure. Despite this concern, no clear definition of aspirin resistance has emerged, and estimates of its incidence have varied remarkably. We aimed to determine the commonality of a mechanistically consistent, stable, and specific phenotype of true pharmacological resistance to aspirin-such as might be explained by genetic causes. METHODS AND RESULTS: Healthy volunteers (n=400) were screened for their response to a single oral dose of 325-mg immediate release or enteric coated aspirin. Response parameters reflected the activity of the molecular target of aspirin, cyclooxygenase-1. Individuals who appeared aspirin resistant on 1 occasion underwent repeat testing, and if still resistant were exposed to low-dose enteric coated aspirin (81 mg) and clopidogrel (75 mg) for 1 week each. Variable absorption caused a high frequency of apparent resistance to a single dose of 325-mg enteric coated aspirin (up to 49%) but not to immediate release aspirin (0%). All individuals responded to aspirin on repeated exposure, extension of the postdosing interval, or addition of aspirin to their platelets ex vivo. CONCLUSIONS: Pharmacological resistance to aspirin is rare; this study failed to identify a single case of true drug resistance. Pseudoresistance, reflecting delayed and reduced drug absorption, complicates enteric coated but not immediate release aspirin administration. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT00948987.

Non-steroidal anti-inflammatory drug use in chronic pain conditions with special emphasis on the elderly and patients with relevant comorbidities: management and mitigation of risks and adverse effects.

PURPOSE: Non-steroidal anti-inflammatory drugs (NSAIDs) are among the most frequently used drugs, and this widespread use is complicated by safety issues. METHOD: A Literature review was conducted. RESULTS: NSAIDs are a leading cause of drug-related morbidity, especially in the elderly and patients with comorbidities. Most adverse effects are related to generalized inhibition of the major targets of NSAIDs: cyclooxygenases I and II. These enzymes are not only involved in pain and inflammation pathogenesis but are also required in the gastrointestinal (GI) tract for mucosal protection and gut motility, and in the kidneys for functional integrity. Thus, the mechanisms of NSAID toxicity are well understood, but the consequences are largely uncontrolled in clinical practice. GI ulcers, including bleeding ulcers, may occur in several percent of all chronic unprotected, high-dose NSAID users. Renal side effects may precipitate renal failure, resulting in acute dialysis and chronic retention. This includes sodium retention, resulting in arterial hypertension, heart failure, and atherosclerotic events. Cardiovascular risk may be tripled by chronic high-dose NSAID use in long-term clinical trials though "real-life studies" indicate lower risk ratios. Off-target side effects include allergic reactions, drug-induced liver injury, and central nervous system effects. CONCLUSIONS: Management of pain and inflammation must consider those risks and find alternative drugs or approaches to limit the negative impact of NSAIDs on mortality and morbidity. Alternative drugs, low-dose/short-term use, but especially non-pharmacologic approaches, such as physiotherapy, exercise, neurophysiologic measures, and local therapies, need to be further utilized. The appalling equation "less pain-more deaths/morbidity" ultimately necessitates treatment optimization in the individual patient.

Tetra- and pentacyclic triterpene acids from the ancient anti-inflammatory remedy frankincense as inhibitors of microsomal prostaglandin E(2) synthase-1.

The microsomal prostaglandin E2 synthase (mPGES)-1 is the terminal enzyme in the biosynthesis of prostaglandin (PG)E2 from cyclooxygenase (COX)-derived PGH2. We previously found that mPGES-1 is inhibited by boswellic acids (IC50 = 3-30 µM), which are bioactive triterpene acids present in the anti-inflammatory remedy frankincense. Here we show that besides boswellic acids, additional known triterpene acids (i.e., tircuallic, lupeolic, and roburic acids) isolated from frankincense suppress mPGES-1 with increased potencies. In particular, 3α-acetoxy-8,24-dienetirucallic acid (6) and 3α-acetoxy-7,24-dienetirucallic acid (10) inhibited mPGES-1 activity in a cell-free assay with IC50 = 0.4 µM, each. Structure-activity relationship studies and docking simulations revealed concrete structure-related interactions with mPGES-1 and its cosubstrate glutathione. COX-1 and -2 were hardly affected by the triterpene acids (IC50 > 10 µM). Given the crucial role of mPGES-1 in inflammation and the abundance of highly active triterpene acids in frankincence extracts, our findings provide further evidence of the anti-inflammatory potential of frankincense preparations and reveal novel, potent bioactivities of tirucallic acids, roburic acids, and lupeolic acids.

Low-dose aspirin in primary prevention: cardioprotection, chemoprevention, both, or neither?

Low-dose aspirin has been shown to be effective in preventing about one-fifth of atherothrombotic vascular complications (non-fatal myocardial infarction, non-fatal stroke, or vascular death) in a meta-analysis of 16 secondary prevention trials in patients with previous myocardial infarction, stroke, or transient cerebral ischaemia. This corresponds to an absolute reduction of about 10-20 per 1000 patients in the yearly incidence of non-fatal events, and to a smaller, but still definite, reduction in vascular death. Against this benefit, the absolute increase in major extracranial bleeding complications [mostly, gastrointestinal (GI)] is 20- to 50-fold smaller, depending on age and sex. Hence, for secondary prevention, the benefits of antiplatelet therapy substantially exceed the risks. For primary prevention, the balance between vascular events avoided and major bleeds caused by aspirin is substantially uncertain because the risks without aspirin, and hence the absolute benefits of antiplatelet prophylaxis, are at least an order of magnitude lower than in secondary prevention. The aim of this article is to review the updated evidence for the efficacy and safety of low-dose aspirin in primary prevention and to discuss additional health benefits resulting from prolonged antiplatelet therapy in apparently healthy people at low average risk of vascular events.