Cyclooxygenase (COX) and 5-lipoxygenase (5-LOX) selectivity of COX inhibitors

Green-synthesized silver nanoparticles from Zingiber officinale extract: antioxidant potential, biocompatibility, anti-LOX properties, and in silico analysis

INTRODUCTION

Zingiber officinale extract has emerged as a compelling candidate for green synthesis of nanoparticles, offering diverse applications across medicine, cosmetics, and nutrition. This study delves into the investigation of in vitro toxicity and explores the biomedical utility of green-synthesized silver nanoparticles derived from ginger extract (GE-AgNPs).

METHODS

We employed established protocols to evaluate in vitro aspects such as antioxidant capacity, anti-inflammatory potential, and biocompatibility of GE-AgNPs. Additionally, molecular docking was employed to assess their anti-lipoxygenase (anti-LOX) activity.

RESULTS

Our findings highlight that the extraction of ginger extract at a pH of 6, utilizing a cosolvent blend of ethanol and ethyl acetate in a 1:1 ratio, yields heightened antioxidant capacity attributed to its rich phenolic and flavonoid content. In the context of silver nanoparticle synthesis, pH 6 extraction yields the highest quantity of nanoparticles, characterized by an average size of 32.64 ± 1.65 nm. Of particular significance, GE-AgNPs (at pH 6) demonstrated remarkable efficacy in scavenging free radicals, as evidenced by an IC50 value of 6.83 ± 0.47 µg/mL. The results from the anti-LOX experiment indicate that GE-AgNPs, at a concentration of 10 µg/mL, can inhibit LOX activity by 25%, outperforming ginger extract which inhibits LOX by 17-18%. Notably, clionasterol exhibited higher binding energy and enhanced stability (-8.9 kcal/mol) compared to nordihydroguaiaretic acid. Furthermore, a cell viability study confirmed the safety of GE-AgNPs at a concentration of 17.52 ± 7.00 µg/mL against the L929 cell line.

CONCLUSION

These comprehensive findings underscore the significant biomedical advantages of GE-AgNPs and emphasize their potential incorporation into cosmetic products at a maximum concentration of 10 µg/mL.

N,N-Disubstituted 4-Sulfamoylbenzoic Acid Derivatives as Inhibitors of Cytosolic Phospholipase A2α: Synthesis, Aqueous Solubility, and Activity in a Vesicle and a Whole Blood Assay

BACKGROUND

Cytosolic phospholipase A2α (cPLA2α) is the key enzyme that initiates the arachidonic acid cascade through which pro-inflammatory lipid mediators can be formed. Therefore, cPLA2α is considered an interesting target for the development of anti-inflammatory drugs. Although several effective inhibitors of the enzyme have been developed, none of them has yet reached clinical application.

OBJECTIVE

Recently, we have prepared new 4-sulfamoylbenzoic acid derivatives based on a cPLA2α inhibitor found in a ligand-based virtual screening. The most effective of these compounds were now subjected to further variations in which the substitution pattern on the sulfamoyl nitrogen atom was changed..

METHODS

The new compounds were tested in vitro in a vesicle assay for cPLA2α inhibition as well as for their water solubility, metabolic stability, and selectivity towards related enzymes. In addition, they were evaluated ex vivo in a whole blood assay in which metabolites of the arachidonic acid cascade formed after activation of cPLA2α were quantified using a combined online dilution/ online solid phase extraction HPLC-MS method.

RESULTS

Inhibitors with submicromolar inhibitory in vitro potency were found with favourable water solubility and selectivity. However, their efficacy did not match that of the highly effective, known, structurally related cPLA2α inhibitor giripladib, which was also tested as a reference. One advantage of some of the new compounds compared to giripladib was their significantly improved water solubility. When analyzing the substances in the ex vivo whole blood assay, it was found that the obtained inhibition data correlated better with the in vivo results when the phorbol ester 12-Otetradecanoylphorbol- 13-acetate was used for activation of the enzyme in the blood cells instead of the calcium ionophore A23187.

CONCLUSION

New compounds with good activity towards cPLA2α and reasonable physicochemical properties were identified. Overall, the results obtained could be helpful in the development of clinically applicable inhibitors of this enzyme.

Identification of NSAIDs as lipoxygenase inhibitors through highly sensitive chemiluminescence method, expression analysis in mononuclear cells and computational studies

Here we report the inhibitory effects of nine non-steroidal anti-inflammatory drugs (NSAIDs) on soybean 15-lipoxygenase (15-LOX) enzyme (EC 1.13.11.12) by three different methods; UV-absorbance, colorimetric and chemiluminescence methods. Only two drugs, Ibuprofen and Ketoprofen, exhibited enzyme inhibition by UV-absorbance method but none of the drug showed inhibition through colorimetric method. Chemiluminescence method was found highly sensitive for the identification of 15-LOX inhibitors and it was more sensitive and several fold faster than the other methods. All tested drugs showed 15-LOX-inhibition with IC₅₀ values ranging from 3.52 ± 0.08 to 62.6 ± 2.15 µM by chemiluminescence method. Naproxen was the most active inhibitor (IC₅₀ 3.52 ± 0.08 µM) followed by Aspirin (IC₅₀ 4.62 ± 0.11 µM) and Acetaminophen (IC₅₀ 6.52 ± 0.14 µM). Ketoprofen, Diclofenac and Mefenamic acid showed moderate inhibitory profiles (IC₅₀ 24.8 ± 0.24 to 39.62 ± 0.27 µM). Piroxicam and Tenoxicam were the least active inhibitors with IC₅₀ values of 62.6 ± 2.15 µM and 49.5 ± 1.13 µM, respectively. These findings are supported by expression analysis, molecular docking studies and density functional theory calculations. The expression analysis and flow cytometry apoptosis analysis were carried out using mononuclear cells (MNCs) which express both human 15-LOX and 5-LOX. Selected NSAIDs did not affect the cytotoxic activity of MNCs at IC₅₀ concentrations and the cell death showed dose dependent effect. However, MNCs apoptosis increased only at the higher concentrations, demonstrating that these drugs may not induce loss of immunity in septic and other inflammatory conditions at the acceptable inhibitory concentrations. The data collectively suggests that NSAIDs not only inhibit COX enzymes as reported in the literature but soybean 15-LOX and MNCs LOXs are also inhibited at differential values. A comparison of the metabolomics studies of arachidonic acid pathway after inhibition of either COX or LOX enzymes may reconfirm these findings.

Treatment with either COX-2 inhibitor or 5-LOX inhibitor causes no compensation between COX-2 pathway and 5-LOX pathway in chronic aluminum overload-induced liver injury in rats

This study was designed to observe the compensation between cyclooxygenase-2 pathway and 5-lipoxygenase pathway in chronic aluminum overload-induced liver injury rats. A rat hepatic injury model of chronic aluminum injury was established by the intragastric administration of aluminum gluconate (Al3 + 200 mg/kg per day, 5 days a week for 20 weeks). The COX-2 inhibitor [meloxicam (1 mg/kg)] and 5-LOX inhibitor [caffeic acid (30 mg/kg)] were intragastrically administered 1 h after aluminum administration. The histopathology was detected by hematoxylin-eosin staining. A series of biochemical indicators were measured with biochemistry assay or ELISAs. The expressions of COX-2 and 5-LOX were measured by immunohistochemistry. Our experimental results showed that aluminum overload caused a significant damage to the liver and also significantly increased the expressions of COX-2, 5-LOX and the levels of inflammation and oxidative stress. The administration of meloxicam and caffeic acid significantly protected livers against histopathological injury, significantly decreased plasma ALT, AST, and ALP levels, significantly decreased TNF-α, IL-6, IL-1β levels, and oxidative stress. However, the administration of caffeic acid did not significantly increase the expression of COX-2 compared with the model group. On the other hand, the administration of meloxicam also did not significantly increase the expression of 5-LOX compared with the model group. Our results indicate that there is no compensation between COX-2 pathway and 5-LOX pathway by inhibiting either COX-2 or 5-LOX in chronic aluminum overload-induced liver injury rat.

Docosapentaenoic acid (DPA, 22:5n-3) ameliorates inflammation in an ulcerative colitis model

DPA showed an anti-inflammatory profile by competing with AA to decrease the synthesis of pro-inflammatory eicosanoids (LTB₄ and PGE₂).

Novel Allosteric Activators for Ferroptosis Regulator Glutathione Peroxidase 4

Glutathione peroxidase 4 (GPX4) is essential for cell membrane repair, inflammation suppression, and ferroptosis inhibition. GPX4 upregulation provides unique drug discovery opportunities for inflammation and ferroptosis-related diseases. However, rational design of protein activators is challenging. Until now, no compound has been reported to activate the enzyme activity of GPX4. Here, we identified a potential allosteric site in GPX4 and successfully found eight GPX4 activators using a novel computational strategy and experimental studies. Compound 1 from the virtual screen increased GPX4 activity, suppressed ferroptosis, reduced pro-inflammatory lipid mediator production, and inhibited NF-κB pathway activation. Further chemical synthesis and structure-activity relationship studies revealed seven more activators. The strongest compound, 1d4, increased GPX4 activity to 150% at 20 μM in the cell-free assay and 61 μM in cell extracts. Therefore, we demonstrated that GPX4 can be directly activated using chemical compounds to suppress ferroptosis and inflammation. Meanwhile, the discovery of GPX4 activators verified the possibility of rational design of allosteric activators.

Modulating effect of inositol hexaphosphate on arachidonic acid-dependent pathways in colon cancer cells

Cyclooxygenase (COX) and lipoxygenase (LOX) are key enzymes of arachidonic acid metabolism. Their products, prostaglandins and leukotrienes, are involved in the pathogenesis of inflammatory bowel diseases and colorectal cancer. The aim of the study was to examine the influence of inositol hexaphosphate (IP6), a naturally occurring phytochemical, on the expression of genes encoding COX and LOX isoforms and synthesis of their products (PGE₂ and LTB₄) in colon cancer cell line Caco-2 stimulated with pro-inflammatory agents (IL-1β/TNFα). Real-time RT-qPCR was used to validate mRNAs level of examined genes. The concentrations of COX-2 and 5-LOX proteins as well as PGE2 and LTB4 were determined by the ELISA method. Based on these studies it may be concluded that IP6 may limit inflammatory events in the colonic epithelium and prevent colon carcinomas by modulating the expression of genes encoding COX and LOX isoforms at both mRNA and protein levels as well as by affecting the synthesis and secretion of prostaglandins and leukotrienes.

Nonsteroidal Anti-Inflammatory Therapy: A Journey Toward Safety

The efficacy of nonsteroidal anti-inflammatory drugs (NSAIDs) against inflammation, pain, and fever has been supporting their worldwide use in the treatment of painful conditions and chronic inflammatory diseases until today. However, the long-term therapy with NSAIDs was soon associated with high incidences of adverse events in the gastrointestinal tract. Therefore, the search for novel drugs with improved safety has begun with COX-2 selective inhibitors (coxibs) being straightaway developed and commercialized. Nevertheless, the excitement has fast turned to disappointment when diverse coxibs were withdrawn from the market due to cardiovascular toxicity. Such events have once again triggered the emergence of different strategies to overcome NSAIDs toxicity. Here, an integrative review is provided to address the breakthroughs of two main approaches: (i) the association of NSAIDs with protective mediators and (ii) the design of novel compounds to target downstream and/or multiple enzymes of the arachidonic acid cascade. To date, just one phosphatidylcholine-associated NSAID has already been approved for commercialization. Nevertheless, the preclinical and clinical data obtained so far indicate that both strategies may improve the safety of nonsteroidal anti-inflammatory therapy.

CUSP9* treatment protocol for recurrent glioblastoma: aprepitant, artesunate, auranofin, captopril, celecoxib, disulfiram, itraconazole, ritonavir, sertraline augmenting continuous low dose temozolomide

CUSP9 treatment protocol for recurrent glioblastoma was published one year ago. We now present a slight modification, designated CUSP9*. CUSP9* drugs--aprepitant, artesunate, auranofin, captopril, celecoxib, disulfiram, itraconazole, sertraline, ritonavir, are all widely approved by regulatory authorities, marketed for non-cancer indications. Each drug inhibits one or more important growth-enhancing pathways used by glioblastoma. By blocking survival paths, the aim is to render temozolomide, the current standard cytotoxic drug used in primary glioblastoma treatment, more effective. Although esthetically unpleasing to use so many drugs at once, the closely similar drugs of the original CUSP9 used together have been well-tolerated when given on a compassionate-use basis in the cases that have come to our attention so far. We expect similarly good tolerability for CUSP9*. The combined action of this suite of drugs blocks signaling at, or the activity of, AKT phosphorylation, aldehyde dehydrogenase, angiotensin converting enzyme, carbonic anhydrase -2,- 9, -12, cyclooxygenase-1 and -2, cathepsin B, Hedgehog, interleukin-6, 5-lipoxygenase, matrix metalloproteinase -2 and -9, mammalian target of rapamycin, neurokinin-1, p-gp efflux pump, thioredoxin reductase, tissue factor, 20 kDa translationally controlled tumor protein, and vascular endothelial growth factor. We believe that given the current prognosis after a glioblastoma has recurred, a trial of CUSP9* is warranted.

Scuba diving induces nitric oxide synthesis and the expression of inflammatory and regulatory genes of the immune response in neutrophils

OBJECTIVE

Scuba diving, characterized by hyperoxia and hyperbaria, could increase reactive oxygen species production which acts as signaling molecules to induce adaptation against oxidative stress. The aim was to study the effects of scuba diving immersion on neutrophil inflammatory response, the induction of oxidative damage, and the NO synthesis.

DESIGN

Nine male divers performed a dive at 50 m depth for a total time of 35 min. Blood samples were obtained at rest before the dive, after the dive, and 3 h after the diving session.

MEASUREMENTS

Markers of oxidative and nitrosative damage, nitrite, and the gene expression of genes related with the synthesis of nitric oxide and lipid mediators, cytokine synthesis, and inflammation were determined in neutrophils.

RESULTS

The mRNA levels of genes related with the inflammatory and immune response of neutrophils, except TNF-α, myeloperoxidase, and toll-like receptor (TLR) 2, significantly increased after the recovery period respect to predive and postdive levels. NF-κB, IL-6, and TLR4 gene expression reported significant differences immediately after diving respect to the predive values. Protein nitrotyrosine levels significantly rose after diving and remained high during recovery, whereas no significant differences were reported in malondialdehyde. Neutrophil nitrite levels as indicative of inducible nitric oxide synthase (iNOS) activity progressively increased after diving and recovery. The iNOS protein levels maintained the basal values in all situations.

CONCLUSION

Scuba diving which combines hyperoxia, hyperbaria, and acute exercise induces nitrosative damage with increased nitrotyrosine levels and an inflammatory response in neutrophils.

Inhibition of cyclooxygenase-2 prevents adverse effects induced by phosphodiesterase type 4 inhibitors in rats

BACKGROUND AND PURPOSE

Phosphodiesterase type 4 (PDE4) inhibitors such as roflumilast are currently being developed as anti-inflammatory treatments for chronic airway disorders. However, high doses of PDE4 inhibitors have also been linked to several side effects in different animal species, including pro-inflammatory effects in the rat. Here, we analysed PDE4-related toxicological findings in a rat model and how these side effects might be therapeutically prevented.

EXPERIMENTAL APPROACH

Wistar rats were treated orally once daily with 10 mg·kg⁻¹ roflumilast for 4 days. Macroscopic changes were monitored throughout the study and further parameters were analysed at the end of the experiment on day 5. In addition, the effects of concomitant treatment with cyclooxygenase (COX) inhibitors were assessed.

KEY RESULTS

Supratherapeutical treatment with roflumilast induced marked body and spleen weight loss, diarrhea, increased secretory activity of the harderian glands, leukocytosis, increased serum cytokine-induced neutrophil chemoattractant-1 (CINC-1) levels, and histopathological changes in thymus, spleen, mesentery and mesenteric lymph nodes. All these toxicological findings could be prevented by the non-steroidal anti-inflammatory drug (NSAID) and non-selective COX inhibitor, diclofenac, given orally. Similar protective effects could be achieved by the COX-2 selective inhibitor lumiracoxib, whereas the COX-1 selective inhibitor SC-560 was generally not effective.

CONCLUSIONS AND IMPLICATIONS

Treatment with an NSAID inhibiting COX-2 prevents the major effects found after subchronic overdosing with the PDE4-specific inhibitor roflumilast. If this effect translates into humans, such combined treatment may increase the therapeutic window of PDE4 inhibitors, currently under clinical development.

Free radical scavenging activities and inhibition of inflammatory enzymes of phenolics isolated from Tripodanthus acutifolius

ETHNOPHARMACOLOGICAL RELEVANCE

Leaf extracts from Tripodanthus acutifolius (Ruiz and Pavón) Van Tieghem have long been used in Argentinean traditional medicine as anti-inflammatory, however, there is no scientific evidence which supports this use in the literature.

AIM OF THE STUDY

The present study was conducted to evaluate the ability of five phenolic compounds purified from infusion prepared from Tripodanthus acutifolius leaves to inhibit key enzymes in inflammatory processes. As anti-inflammatory compounds frequently possess free radical scavenging activities, purified substances were comparatively evaluated to asses their free radical scavenging properties. Genotoxic effects were also evaluated.

MATERIALS AND METHODS

Compounds were evaluated on their ability to inhibit hyaluronidase and cyclooxygenase-2 (COX-2) activities to assess their anti-inflammatory capacities. Free radical scavenging activity was assessed by: 1,1-diphenyl-2-picryl-hydrazyl radical (DPPH), superoxide anion assay and the inhibition on lipid peroxidation. Genotoxicity was evaluated by Bacillus subtilis rec assay.

RESULTS

Fractionation of Tripodanthus acutifolius infusion yielded a novel phenylbutanoid derivative (tripodantoside) and four known flavonoid glycosides (rutin, nicotiflorin, hyperoside and isoquercitrin). Flavonoids produced higher inhibition on hyluronidase activity (IC(50) approximately 1.7 mM) than tripodantoside (IC(50)=27.90 mM). A similar COX-2 inhibition activity was exerted by tripodantoside and monoglycosilated flavonoids (IC(50) approximately 50 microM). Compounds were strong radical scavengers, with effective concentration 50 (EC(50)) values for DPPH in the range of 2.7-6.3 microg/mL, and for superoxide anion in the range of 3.9-8.7 microg/mL. All compounds scavenged peroxyl radicals in the lipid peroxidation assay. The substances showed no genotoxic effects.

CONCLUSIONS

The anti-inflammatory effects, free radical scavenging activities and lack of genotoxicity of purified compounds may support the folk use of infusion from Tripodanthus acutifolius leaves as anti-inflammatory.

The topology of drug-target interaction networks: implicit dependence on drug properties and target families

The availability of interaction data between small molecule drugs and protein targets has increased substantially in recent years. Using seven different databases, we were able to assemble a total of 4767 unique interactions between 802 drugs and 480 targets, which means that on average every drug is currently acknowledged to interact with 6 targets. The application of network theory to the analysis of these data reveals an unexpectedly complex picture of drug-target interactions. The results confirm that the topology of drug-target networks depends implicitly on data completeness, drug properties, and target families. The implications for drug discovery are discussed.