Experimental investigation and molecular simulations of quinone related compounds as COX/LOX inhibitors.

Quinone-containing compounds have risen as promising anti-inflammatory targets; however, very little research has been directed to investigate their potentials. Accordingly, the current study aimed to design and synthesize group of quinones bearing different substituents to investigate the effect of these functionalities on the anti-inflammatory activities of this important scaffold. The choice of these substituents was carefully done, varying from a directly attached heterocyclic ring to different aromatic moieties linked through a nitrogen spacer. Both in vitro and in vivo anti-inflammatory activities of the synthesized compounds were assessed relative to the positive standards: celecoxib and indomethacin. The in vitro enzymatic and transcription inhibitory actions of all the synthesized compounds were tested against cyclooxygenase-2 (COX-2), cyclooxygenase-1 (COX-1), and 5-lipoxygenase (LOX) and the in vivo gene expression of Interleukin-1, interleukin 10, and Tumor Necrosis Factor-α (TNF-α) were determined. The IC50 against COX-1 and COX-2 enzymes obtained by the immunoassay test revealed promising activities of sixteen compounds with selectivity indices higher than 100-fold COX-2 selectivity. Out of those, four compounds revealed selectivity indices comparable to celecoxib as a reference drug. Furthermore, all the tested compounds inhibited LOX with an IC50 in the range of 1.59-3.11 µM superior to that of the reference drug used; zileuton (IC50 = 3.50 µM). Consequently, these results highlight the promising LOX inhibitory activity of the tested compounds. The obtained in vivo paw edema results showed high inhibitory percentage for the compounds 9a, 9b, and 11a with the significant lower TNF-α relative mRNA expression for compounds 5a, 5d, 9a, 9b, 12d, and 12e. Finally, in silico docking of the most active compounds (5b, 5d, 9a, 9b) against COX2 enzymes presented an acceptable justification of the obtained in vitro inhibitory activities. As a conclusion, Compounds 5b, 5d, 9a, 9b, and 11b showed promising results and thus deserves further investigation.

Structure-guided approach on the role of substitution on amide-linked bipyrazoles and its effect on their anti-inflammatory activity.

A structure-guided modelling approach using COX-2 as a template was used to investigate the effect of replacing the chloro atom located at the chlorophenyl ring of amide-linked bipyrazole moieties, aiming at attaining better anti-inflammatory effect with a good safety profile. Bromo, fluoro, nitro, and methyl groups were revealed to be ideal candidates. Consequently, new bipyrazole derivatives were synthesised. The in vitro inhibitory COX-1/COX-2 activity of the synthesised compounds exhibited promising selectivity. The fluoro and methyl derivatives were the most active candidates. The in vivo formalin-induced paw edoema model confirmed the anti-inflammatory activity of the synthesised compounds. All the tested derivatives had a good ulcerogenic safety profile except for the methyl substituted compound. In silico molecular dynamics simulations of the fluoro and methyl poses complexed with COX-2 for 50 ns indicated stable binding to COX-2. Generally, our approach delivers a fruitful matrix for the development of further amide-linked bipyrazole anti-inflammatory candidates.

Quorum sensing inhibitory activity of sub-inhibitory concentrations of ß-lactams.

INTRODUCTION: The virulence factors of Pseudomonas aeruginosa are under the control of quorum sensing (QS) signals. Hence, interference with QS prevents its pathogenesis. OBJECTIVE: The aim of the present research is to assess the influence of some ß-lactam antibiotics on cell communication and the release of different virulence factors. METHODS: The minimal inhibitory concentrations of ceftazidime, cefepime and imipenem were evaluated by microbroth dilution method. The effect of sub-inhibitory concentration of the tested antibiotics on QS signals was investigated using reporter strain assay. In addition, different virulence factors (elastase, protease, pyocyanin and hemolysin) were estimated in the presence of their sub-inhibitory concentrations. RESULTS: Low concentrations of ceftazidime, cefepime and imipenem caused significant elimination of the QS signals 3OH-C12-HSL and C4-HSL up to 1/20 MIC. Furthermore, low concentrations of the tested antimicrobials suppressed virulence factors elastase and hemolysin. Moreover, 1/20 of their MICs reduced elastase, protease, pyocyanin and hemolysin. CONCLUSION: Utilization of ß-lactam antibiotics at low concentrations could be an effective approach for prevention and treatment of P. aeruginosa infection.

Nephroprotective role of dipyridamole in diabetic nephropathy: Effect on inflammation and apoptosis.

AIMS: Inflammation plays significant roles in developing diabetic nephropathy (DN). Adenosine, natural purine nucleoside, acts as potent endogenous anti-inflammatory agent. Extracellular adenosine usually disappears quickly due to rapid uptake into adjacent cells. In this regard; we investigated putative reno-protective effects of dipyridamole, nucleoside transport inhibitor, by exploring its anti-inflammatory mechanisms in-vivo and in-vitro. MAIN METHODS: Daily 6mg/kg/day dipyridamole was given to six-weeks streptozotocin-induced diabetic rats over two-week period in presence/absence of 10mg/kg/day CGS15943, potent non selective adenosine receptors antagonist. Histological changes were assessed in kidney sections. Gene and protein expression of interleukin (IL)-1ß, IL-10, IL-18, tumor necrosis factor (TNF)-α and intercellular adhesion molecule (ICAM)-1 was measured. Activation of apoptotic pathway was demonstrated by measuring the activity of caspase-3/8/9 and activation of c-Jun NH2-terminal kinases (JNK)-mitogen-activated-protein kinase (MAPK). In addition, all markers were measured in human mesangial cells cultured in high glucose. KEY FINDINGS: Diabetes induced marked changes in the glomerular and tubular structure including focal glomerulosclerosis with marked shrinkage of some glomerular tufts. Diabetes resulted in enhanced production of IL-1ß, IL-18, TNF-α and ICAM-1 associated with reduced IL-10 protein level, leading to activation of caspases-3/8/9 and pJNK/JNK in-vivo and in-vitro. Dipyridamole treatment restored diabetes-induced reduction in adenosine levels and resulted in mild glomerular effects and vacuolation of tubular epithelium. Dipyridamole reduced the adhesion molecule, ICAM-1, and restored the normal balance between pro- and anti-inflammatory cytokines in-vivo and in-vitro. SIGNIFICANCE: Dipyridamole prevented the progression of DN by elevating endogenous levels of protecting adenosine, leading to reduction in inflammation and intrinsic apoptosis.

Hepatoprotective and anti-tumor effects of targeting MMP-9 in hepatocellular carcinoma and its relation to vascular invasion markers.

The current study aims to evaluate the hepatoprotective and antitumor efficacy of doxycycline, as an matrix metalloproteases-9 (MMP-9) inhibitor, in an in vivo model of hepatocellular carcinoma (HCC). HCC was induced experimentally by thiocetamide (200 mg/kg) in rats that were treated with doxycycline (5 mg/kg for 16 weeks). Tumor severity was evaluated by measuring α-fetoprotein (AFP) levels, histopathologically by investigating liver sections stained with hematoxylin/eosin and assessing the survival rate. Liver homogenates were used for the measurements of MMP-9, fascin and hepatic heparan sulfate proteoglycan (HSPG) levels. Oxidative stress markers [malonaldehyde (MDA) and glutathione] as well as fibroblast growth factor-2 (FGF-2) gene expression were also among the assessed indicators. HCC in human and animal samples showed significant elevation in the levels of MMP-9 (231.7, 90 %), fascin (33.17, 140 %), as well as FGF-2 gene expression (342 % in animal samples; all respectively), associated with a significant decrease in hepatic HSPG level. Treatment of rats with doxycycline increased the animal survival rate (90 %) and decreased serum AFP level. Moreover, doxycycline ameliorated fibrosis and the induced massive hepatic tissue breakdown. It also restored the integrity of hepatic HSPGs and showed a magnificent inhibitory effect of tumor invasion cascade by significantly reducing the activities of MMP-9 (42 %) and fascin (50 %), as well as reducing the gene expression of FGF-2 (85.7 %). Furthermore, the antioxidant impact of doxycycline was evidenced by the significant elevation in glutathione level and depressing MDA level. To this end, doxycycline, proved promising hepatoprotective and antitumor activity and opens, thereby, a new horizon against vascular migration ability of the tumor cells.

Aspirin is an efficient inhibitor of quorum sensing, virulence and toxins in Pseudomonas aeruginosa.

Quorum sensing (QS) plays a vital role in regulation of virulence factors and toxins in Pseudomonas aeruginosa, which can cause serious human infections. Therefore, the QS system in P. aeruginosa may be an important target for pharmacological intervention. Activity of aspirin on the QS system was assessed using a reporter strain assay and confirmed using RT-PCR to test expression of virulence factors and toxins. In addition, molecular modeling techniques including docking, flexible alignment and surface mapping were also applied to further understand aspirin's potential QS inhibition activity. Aspirin (6 mg/ml) showed significant reduction (p < 0.01) of quorum sensing signals in P. aeruginosa, including expression of elastase, total proteases, and pyocyanin (p < 0.01) without affecting bacterial viability. Aspirin also significantly reduced organism motility and biofilm production (p < 0.01) and decreased expression of lasI, lasR, rhlI, rhlR, pqsA and pqsR genes by 38, 72, 69, 72, 74 and 43% respectively. Moreover, the expression of Pseudomonas toxins exoS and exoY was reduced by 47 and 55% respectively. The molecular modeling analysis suggests the QS inhibitory action of aspirin occurs through interaction of aspirin's aryl group and Tyr-88 of the LasR receptor, by strong π-π stacking interactions, which associated with a conformational change of the receptor-aspirin complex. The inhibitory effect of aspirin on virulence factors was specific to P. aeruginosa as aspirin at sub-MIC did not affect the biofilm or motility of Escherichia coli. To summarize, the collective data demonstrate that low concentrations of aspirin inhibit quorum sensing of P. aeruginosa.

Suramin inhibits hepatic tissue damage in hepatocellular carcinoma through deactivation of heparanase enzyme.

Hepatocellular carcinoma (HCC) is resistant to conventional chemotherapy, and is rarely amenable to radiotherapy. Heparanase, enzyme attacks heparan sulfate proteoglycans (HSPGs), is preferentially expressed in human tumors and its overexpression in low-metastatic tumor confers a highly invasive phenotype in experimental animals. Meanwhile, high doses of suramin dramatically increase tissue glycosaminoglycans due, in part, to inhibition of heparanase enzymes. Therefore, the following study was conducted to evaluate the chemopreventive and hepatoprotective effects of suramin in in-vivo model of HCC. Therefore, HCC was induced in SD rats by thioacetamide (200mg/kg) in presence/absence of suramin (20mg/kg). Liver impairment was assessed by measuring serum α-fetoprotein and investigating liver sections stained with Hematoxylin/Eosin. Hepatic HSPGs and heparanse were measured by ELISA. Glucosamine and glucuronic acid were measured by chemical methods. Gene expression of fibroblast growth factor (FGF)-2 and caspase-3 was measured. Apoptotic pathway was evaluated by measuring the activity of caspase-3/8/9. Suramin increased the animal survival and decreased serum α-fetoprotein. In addition, suramin ameliorated fibrosis and massive hepatic tissue breakdown. Suramin restored hepatic HSPGs and reduced the activity of hepatic heparanase leading to decreased hepatic levels of glucosamine and glucuronic acid. Moreover, suramin reduced the gene expression of FGF-2 and caspase-3. Finally, suramin blocked the elevated activity of caspase-3/8/9. In conclusion, surmain showed antitumor activity as well as hepatoprotective effects. Besides its antioxidant activity, other mechanisms are involved including restoration of HSPGs and inhibition of heparanase and FGF-2. Suramin inhibits intrinsic and extrinsic apoptotic pathway. Targeting HSPGs expression is potential therapeutic target for HCC.

Reno-protective effect of NECA in diabetic nephropathy: implication of IL-18 and ICAM-1.

Diabetic nephropathy (DN) remains the most common cause of end-stage renal disease. Although, adenosine acts as a local modulator with a cytoprotective function, extracellular adenosine usually disappears quickly due to a rapid uptake into adjacent cells. Therefore, we investigated the effect of 5'-(N-ethylcarboxamido)-adenosine (NECA), a stable, nonselective adenosine receptor agonist, on diabetes-induced increases in inflammatory cytokines and adhesion molecules. The enhancement of adenosine receptor action by NECA was examined in the renal tissues of rats with streptozotocin-induced diabetes. Daily i.p. injections of NECA at 0.3 mg/kg/day were given to rats, over a two-week period, six weeks after the induction of diabetes. Morphological changes were assessed in kidney sections. Oxidative stress was examined by measuring tissue malondialdehyde. Gene expression of interleukin (IL)-18, tumor necrosis factor (TNF)-α and intercellular adhesion molecule (ICAM)-1 was measured by real-time PCR. Activation of cellular, proapoptotic pathways was demonstrated by measuring the activation of c-Jun NH(2)-terminal kinases (JNK)-mitogen-activated-protein kinase (MAPK). We found that diabetes-induced malondialdehyde formation activated the production of IL-18, TNF-α and ICAM-1, which, in turn, activated pro-apoptotic pathways in diabetic rats. Treatment with NECA protected diabetic rats by exerting hypoglycemic and antioxidant effects as well as reducing gene expression of proinflammatory cytokines. These effects were associated with deactivation of JNK-MAPK. In addition, diabetic rats treated with NECA showed mild glomerular effects and vacuolation of tubular epithelium. We can conclude that activation of adenosine receptors is a potential therapeutic target in DN. NECA acts via multiple mechanisms including: reducing diabetes-induced oxidative stress, inhibiting gene expression of IL-18, TNF-α and ICAM-1, and blocking activation of the JNK-MAPK pathway.

Real-time nucleic acid sequence-based amplification assay for detection of hepatitis A virus.

A nucleic acid sequence-based amplification (NASBA) assay in combination with a molecular beacon was developed for the real-time detection and quantification of hepatitis A virus (HAV). A 202-bp, highly conserved 5' noncoding region of HAV was targeted. The sensitivity of the real-time NASBA assay was tested with 10-fold dilutions of viral RNA, and a detection limit of 1 PFU was obtained. The specificity of the assay was demonstrated by testing with other environmental pathogens and indicator microorganisms, with only HAV positively identified. When combined with immunomagnetic separation, the NASBA assay successfully detected as few as 10 PFU from seeded lake water samples. Due to its isothermal nature, its speed, and its similar sensitivity compared to the real-time RT-PCR assay, this newly reported real-time NASBA method will have broad applications for the rapid detection of HAV in contaminated food or water.

Combined immunomagnetic separation-molecular beacon-reverse transcription-PCR assay for detection of hepatitis A virus from environmental samples.

In this study, a molecular-beacon-based real-time reverse transcription (RT)-PCR assay was developed to detect the presence of hepatitis A virus (HAV) in environmental samples. A 125-bp, highly conserved 5' noncoding region of HAV was targeted. The sensitivity of the real-time RT-PCR assay was tested with 10-fold dilutions of viral RNA, and a detection limit of 1 PFU was obtained. The specificity of the assay was demonstrated by testing with other environmental pathogens and indicator microorganisms, and only HAV was positively identified. When combined with immunomagnetic separation, the real-time RT-PCR assay successfully detected as few as 20 PFU in seeded groundwater samples. Because of its simplicity and specificity, this assay has broad applications for the rapid detection of HAV in contaminated foods or water.