Crystal Structure of Aspirin-Acetylated Human Cyclooxygenase-2: Insight into the Formation of Products with Reversed Stereochemistry

Virtual Screening and Molecular Docking to Study the Mechanism of Chinese Medicines in the Treatment of Coronavirus Infection

BACKGROUND Heat-clearing and detoxifying herbs (HDHs) play an important role in the prevention and treatment of coronavirus infection. However, their mechanism of action needs further study. This study aimed to explore the anti-coronavirus basis and mechanism of HDHs. MATERIAL AND METHODS Database mining was performed on 7 HDHs. Core ingredients and targets were screened according to ADME rules combined with Neighborhood, Co-occurrence, Co-expression, and other algorithms. GO enrichment and KEGG pathway analyses were performed using the R language. Finally, high-throughput molecular docking was used for verification. RESULTS HDHs mainly acts on NOS3, EGFR, IL-6, MAPK8, PTGS2, MAPK14, NFKB1, and CASP3 through quercetin, luteolin, wogonin, indirubin alkaloids, ß-sitosterol, and isolariciresinol. These targets are mainly involved in the regulation of biological processes such as inflammation, activation of MAPK activity, and positive regulation of NF-kappaB transcription factor activity. Pathway analysis further revealed that the pathways regulated by these targets mainly include: signaling pathways related to viral and bacterial infections such as tuberculosis, influenza A, Ras signaling pathways; inflammation-related pathways such as the TLR, TNF, MAPK, and HIF-1 signaling pathways; and immune-related pathways such as NOD receptor signaling pathways. These pathways play a synergistic role in inhibiting lung inflammation and regulating immunity and antiviral activity. CONCLUSIONS HDHs play a role in the treatment of coronavirus infection by regulating the body's immunity, fighting inflammation, and antiviral activities, suggesting a molecular basis and new strategies for the treatment of COVID-19 and a foundation for the screening of new antiviral drugs.

An outlook on suicide enzyme inhibition and drug design

There have been recent renewed interests in the importance of suicide enzyme inhibition. The principal objective of this review is to investigate all types of suicide inhibitions for natural enzymes, artificial biocatalysts as well as therapeutic potential of enzyme suicide inhibition. It is discussed the suicide inhibition beneficial in drug design and treatments and non-beneficial achievements for some industrial enzymes such as HRP peroxidase enzyme. The design of biomimetic artificial enzymes explained to prevent inhibition by protecting the active site via environmental conditions. Suicide enzyme inhibition development can be the key mechanism against sever diseases such as SARS. In this report, suicide enzyme inactivation classes are classified based on target enzyme groups via their substrates.

Characterization, molecular modeling and pharmacology of some 2́-hydroxychalcone derivatives as SARS-CoV-2 inhibitor

This work presented the microwave assisted synthesis of six new 2́-hydroxychalcones and their characterization based on FTIR, UV-Vis, ¹H NMR, and mass spectral analysis. Quantum chemical studies confirmed the structures of prepared chalcones. Antioxidant, in vitro antimicrobial and in silico antiviral studies have been performed to evaluate their biological performance. Results of molecular docking of prepared 2́-hydroxychalcones against SARS-CoV-2 (7BQY) main protease disclosed their inhibition which is comparable to standard, remdesivir and better than hydroxychloroquine (HCQ). ADMET prediction revealed them to be non-carcinogenic and relatively safe.

Full-length transcriptomic analysis reveals osmoregulatory mechanisms in Coilia nasus eyes reared under hypotonic and hyperosmotic stress

In recent years, sea-level rise, caused by global warming, will trigger salinity changes. This will threaten the survival of aquatic animals. Till now, the osmoregulatory mechanism of Coilia nasus eyes has not been yet explored. Oxford Nanopore Technologies (ONT) sequencing was performed in C. nasus eyes during hypotonic and hyperosmotic stress for the first time. 22.5G clean reads and 26,884 full-length non-redundant sequences were generated via ONT sequencing. AS events, APA, TF, and LncRNA were identified. During hypotonic stress, 46 up-regulated DEGs and 28 down-regulated DEGs were identified. During hypertonic stress, 190 up-regulated DEGs and 182 down-regulated DEGs were identified. These DEGs were associated with immune, metabolism, and transport responses. The expression of these DEGs indicated that apoptosis and inflammation were triggered during hypotonic and hyperosmotic stress. To resist hypotonic stress, polyamines metabolism and transport of Na⁺ and Cl^- from inter-cellular to extra-cellular were activated. During hyperosmotic stress, amino acids metabolism and transport of myo-inositol and Na⁺ from extra-cellular to inter-cellular were activated, while Cl^- transport was inhibited. Moreover, different transcript isoforms generated from the same gene performed different expression patterns during hypotonic and hypertonic stress. These findings will be beneficial to understand osmoregulatory mechanism of C. nasus eyes, and can also improve our insights on the adaptation of aquatic animals to environmental changes.

Investigating the Mechanism of Scutellariae barbata Herba in the Treatment of Colorectal Cancer by Network Pharmacology and Molecular Docking

Background

Colorectal cancer (CRC) is one of the most common gastrointestinal tumors, which accounts for approximately 10% of all diagnosed cancers and cancer deaths worldwide per year. Scutellariae barbatae Herba (SBH) is one of the most frequently used traditional Chinese medicine (TCM) in the treatment of CRC. Although many experiments have been carried out to explain the mechanisms of SBH, the mechanisms of SBH have not been illuminated fully. Thus, we constructed a network pharmacology and molecular docking to investigate the mechanisms of SBH.

Methods

We adopted active constituent prescreening, target predicting, protein-protein interaction (PPI) analysis, Gene Ontology (GO) analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, differentially expressed gene analysis, and molecular docking to establish a system pharmacology database of SBH against CRC.

Results

A total of 64 active constituents of SBH were obtained and 377 targets were predicted, and the result indicated that quercetin, luteolin, wogonin, and apigenin were the main active constituents of SBH. Glucocorticoid receptor (NR3C1), pPhosphatidylinositol 4,5-bisphosphate 3-kinase catalytic subunit alpha isoform (PIK3CA), cellular tumor antigen p53 (TP53), transcription factor AP-1 (JUN), mitogen-activated protein kinase 1 (MAPK1), Myc protooncogene protein (MYC), cyclin-dependent kinase 1 (CDK1), and broad substrate specificity ATP-binding cassette transporter ABCG2 (ABCG2) were the major targets of SBH in the treatment of CRC. GO analysis illustrated that the core biological process regulated by SBH was the regulation of the cell cycle. Thirty pathways were presented and 8 pathways related to CRC were involved. Molecular docking presented the binding details of 3 key targets with 6 active constituents.

Conclusions

The mechanisms of SBH against CRC depend on the synergistic effect of multiple active constituents, multiple targets, and multiple pathways.

Natural COX-2 Inhibitors as Promising Anti-inflammatory Agents: An Update

COX-2, a key enzyme that catalyzed the rate-limiting steps in the conversion of arachidonic acid to prostaglandins, played a pivotal role in the inflammatory process. Different from other family members, COX-2 was barely detectable in normal physiological conditions and highly inducible during the acute inflammatory response of human bodies to injuries or infections. Therefore, the therapeutic utilization of selective COX-2 inhibitors has already been considered as an effective approach for the treatment of inflammation with diminished side effects. Currently, both traditional and newer NSAIDs are the commonly prescribed medications that treat inflammatory diseases by targeting COX-2. However, due to the cardiovascular side-effects of the NSAIDs, finding reasonable alternatives for these frequently prescribed medicines are a hot spot in medicinal chemistry research. Naturallyoccurring compounds have been reported to inhibit COX-2, thereby possessing beneficial effects against inflammation and certain cell injury. The review mainly concentrated on recently identified natural products and derivatives as COX-2 inhibitors, the characteristics of their structural core scaffolds, their anti-inflammatory effects, molecular mechanisms for enzymatic inhibition, and related structure-activity relationships. According to the structural features, the natural COX-2 inhibitors were mainly divided into the following categories: natural phenols, flavonoids, stilbenes, terpenoids, quinones, and alkaloids. Apart from the anti-inflammatory activities, a few dietary COX-2 inhibitors from nature origin also exhibited chemopreventive effects by targeting COX-2-mediated carcinogenesis. The utilization of these natural remedies in future cancer prevention was also discussed. In all, the survey on the characterized COX-2 inhibitors from natural sources paves the way for the further development of more potent and selective COX-2 inhibitors in the future.

New nitric oxide-releasing indomethacin derivatives with 1,3-thiazolidine-4-one scaffold: Design, synthesis, in silico and in vitro studies

In this study we present design and synthesis of nineteen new nitric oxide-releasing indomethacin derivatives with 1,3-thiazolidine-4-one scaffold (NO-IND-TZDs) (6a-s), as a new safer and efficient multi-targets strategy for inflammatory diseases. The chemical structure of all synthesized derivatives (intermediaries and finals) was proved by NMR and mass spectroscopic analysis. In order to study the selectivity of NO-IND-TZDs for COX isoenzymes (COX-1 and COX-2) a molecular docking study was performed using AutoDock 4.2.6 software. Based on docking results, COX-2 inhibitors were designed and 6o appears as the most selective derivative which showed an improved selective index compared with indomethacin (IND) and diclofenac (DCF), used as reference drugs. The biological evaluation of 6a-s, using in vitro assays has included the anti-inflammatory and antioxidant effects as well as the nitric oxide (NO) release. Referring to the anti-inflammatory effects, the most active compound was 6i, which was more active than IND and aspirin (ASP) in term of denaturation effect, on bovine serum albumin (BSA), as indirect assay to predict the anti-inflammatory effect. An appreciable anti-inflammatory effect, in reference with IND and ASP, was also showed by 6k, 6c, 6q, 6o, 6j, 6d. The antioxidant assay revealed the compound 6n as the most active, being 100 times more active than IND. The compound 6n showed also the most increase capacity to release NO, which means is safer in terms of gastro-intestinal side effects. The ADME-Tox study revealed also that the NO-IND-TZDs are generally proper for oral administration, having optimal physico-chemical and ADME properties. We can conclude that the compounds 6i and 6n are promising agents and could be included in further investigations to study in more detail their pharmaco-toxicological profile.

Bioinformatics analysis of a TF-miRNA-lncRNA regulatory network in major depressive disorder

Major depressive disorder (MDD) is a highly prevalent disease and one of the main causes of disability worldwide. Although many studies have partially revealed the occurrence and development process of MDD, the pathogeny and molecular mechanisms are not fully understood. Weighted gene coexpression network analysis (WGCNA) was used to explore the co-expression modules and hub genes in MDD. A protein-protein interaction (PPI) network of the most significant module and a TF-miRNA-lncRNA regulatory network of MDD were constructed using bioinformatics analysis tools. A KEGG pathway and gene ontology (GO) functional enrichment analysis of the genes in the significant module was performed using DAVID. Five hub genes in the PPI network and 10 genes in the TF-miRNA-lncRNA regulatory network with high degree values were identified, which may provide new insights for the investigation of key pathways, diagnostic bio-markers, and therapeutic targets of MDD. This study brings a novel perspective and provides valuable information to explore the molecular mechanism of MDD.

Blockade of AMPK-Mediated cAMP-PKA-CREB/ATF1 Signaling Synergizes with Aspirin to Inhibit Hepatocellular Carcinoma

Simple Summary

Epidemiological and experimental studies have demonstrated that aspirin (acetylsalicylic acid) may prevent the incidence of some types of human cancer, including colorectal cancer and hepatocellular carcinoma (HCC). In addition, preclinical studies indicate that aspirin in combination with other treatments may achieve a more significant anti-cancer effect for established tumors. This study aims to improve the anti-cancer effect of aspirin by targeting signaling pathways related to aspirin and its targets. We find that aspirin may induce cAMP–PKA–CREB/ATF1 signaling in HCC via AMPK and its downstream target carbamoyl-phosphate synthase 1 (CPS1). Blockade of PKA–CREB/ATF1 signaling by the natural agent berbamine could sensitize HCC to aspirin. This research indicates that the combination of two inexpensive drugs, aspirin and berbamine, holds promise in preventing and treating HCC.

Abstract

Aspirin can prevent or inhibit inflammation-related cancers, such as colorectal cancer and hepatocellular carcinoma (HCC). However, the effectiveness of chemotherapy may be compromised by activating oncogenic pathways in cancer cells. Elucidation of such chemoresistance mechanisms is crucial to developing novel strategies to maximize the anti-cancer effects of aspirin. Here, we report that aspirin markedly induces CREB/ATF1 phosphorylation in HCC cells, which compromises aspirin’s anti-HCC effect. Inhibition of AMP-activated protein kinase (AMPK) abrogates the induction of CREB/ATF1 phosphorylation by aspirin. Mechanistically, activation of AMPK by aspirin results in decreased expression of the urea cycle enzyme carbamoyl-phosphate synthase 1 (CPS1) in HCC cells and xenografts. Treatment with aspirin or CPS1 knockdown stimulates soluble adenylyl cyclase expression, thereby increasing cyclic AMP (cAMP) synthesis and stimulating PKA–CREB/ATF1 signaling. Importantly, abrogation of aspirin-induced CREB/ATF1 phosphorylation could sensitize HCC to aspirin. The bis-benzylisoquinoline alkaloid berbamine suppresses the expression of cancerous inhibitor of protein phosphatase 2A (CIP2A), leading to protein phosphatase 2A-mediated downregulation of CREB/ATF1 phosphorylation. The combination of berbamine and aspirin significantly inhibits HCC in vitro and in vivo. These data demonstrate that the regulation of cAMP-PKA-CREB/ATF1 signaling represents a noncanonical function of CPS1. Targeting the PKA–CREB/ATF1 axis may be a strategy to improve the therapeutic effects of aspirin on HCC.

Herb-target virtual screening and network pharmacology for prediction of molecular mechanism of Danggui Beimu Kushen Wan for prostate cancer

Prostate cancer (PCa) is a cancer that occurs in the prostate with high morbidity and mortality. Danggui Beimu Kushen Wan (DBKW) is a classic formula for patients with difficult urination including PCa. This study aimed to investigate the molecular mechanisms of DBKW for PCa. We obtained DBKW compounds from our previous reviews. We identified potential targets for PCa from literature search, currently approved drugs and Open Targets database and filtered them by protein-protein interaction network analysis. We selected 26 targets to predict three cancer-related pathways. A total of 621 compounds were screened via molecular docking using PyRx and AutoDock Vina against 21 targets for PCa, producing 13041 docking results. The binding patterns and positions showed that a relatively small number of tight-binding compounds from DBKW were predicted to interact strongly and selectively with three targets. The top five high-binding-affinity compounds were selected to generate a network, indicating that compounds from all three herbs had high binding affinity against the 21 targets and may have potential biological activities with the targets. DBKW contains multi-targeting agents that could act on more than one pathway of PCa simultaneously. Further studies could focus on validating the computational results via experimental studies.

Aspirin in the Prevention of Cardiovascular Disease and Cancer

More than a century after its synthesis, daily aspirin, given at a low dose, is a milestone treatment for the secondary prevention of cardiovascular disease (CVD). Its role in primary prevention of CVD is still debated. Older randomized controlled trials showed that aspirin reduced the low incidence of myocardial infarction but correspondingly increased the low incidence of serious gastrointestinal bleeds without altering mortality. More recent trials see the benefit attenuated, perhaps obscured by other cardioprotective practices, while the bleeding risk remains, especially in older patients. Indirect evidence, both preclinical and clinical, suggests that aspirin may protect against sporadic colorectal cancer and perhaps other cancers. However, further studies are still necessary to warrant the consumption of aspirin for primary prevention of CVD and cancer by apparently healthy individuals.

Preparation, COX-2 Inhibition and Anticancer Activity of Sclerotiorin Derivatives

The latest research has indicated that anti-tumor agents with COX-2 inhibitory activity may benefit their anti-tumor efficiency. A series of sclerotiorin derivatives have been synthesized and screened for their cytotoxic activity against human lung cancer cells A549, breast cancer cells MDA-MB-435 using the MTT method. Among them, compounds 3, 7, 12, 13, 15, 17 showed good cytotoxic activity with IC₅₀ values of 6.39, 9.20, 9.76, 7.75, 9.08, and 8.18 μM, respectively. In addition, all compounds were tested in vitro the COX-2 inhibitory activity. The results disclosed compounds 7, 13, 25 and sclerotiorin showed moderate to good COX-2 inhibition with the inhibitory ratios of 58.7%, 51.1%, 66.1% and 56.1%, respectively. Notably, compound 3 displayed a comparable inhibition ratio (70.6%) to the positive control indomethacin (78.9%). Furthermore, molecular docking was used to rationalize the potential of the sclerotiorin derivatives as COX2 inhibitory agents by predicting their binding energy, binding modes and optimal orientation at the active site of the COX-2. Additionally, the structure-activity relationships (SARS) have been addressed.

Identification of Antitumor Active Constituents in Polygonatum sibiricum Flower by UPLC-Q-TOF-MSE and Network Pharmacology

We aimed to investigate the material basis and mechanisms underlying the antitumor activity of Polygonatum sibiricum flower by ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS^E). A compound-protein interaction network for cancer was constructed to identify potential drug targets, and then the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis was conducted to elucidate the pathways involved in the antitumor activity of P. sibiricum flower. Subsequently, molecular docking was performed to determine whether the identified proteins are a target of the compounds of P. sibiricum flower. Sixty-four compounds were identified in P. sibiricum flower. Among these, 35 active constituents and 72 corresponding targets were found to be closely associated with the antitumor activity of P. sibiricum flower. By constructing and analyzing the compound-target-pathway network, five key compounds and 10 key targets were obtained. The five key compounds were wogonin, rhamnetin, dauriporphine, chrysosplenetin B, and 5-hydroxyl-7,8-panicolin. The 10 key targets were PIK3CG, AKT1, PTGS1, PTGS2, MAPK14, CCND1, TP53, GSK3B, NOS2, and SCN5A. In addition, 34 antitumor-related pathways were identified using the KEGG pathway analysis. To further verify the results of network pharmacology screening, molecular docking was performed with the five key compounds and the top three targets based on degree ranking, namely, PIK3CG, AKT1, and PTGS2; the results of molecular docking were consistent with those of network pharmacology. P. sibiricum flower can exert its antitumor activity via multicomponent, multitarget, and multichannel mechanisms of action. In this study, we identified the antitumor active constituents of P. sibiricum flower and their potential mechanisms of action.

Targeting Lipid Peroxidation for Cancer Treatment

Cancer is one of the highest prevalent diseases in humans. The chances of surviving cancer and its prognosis are very dependent on the affected tissue, body location, and stage at which the disease is diagnosed. Researchers and pharmaceutical companies worldwide are pursuing many attempts to look for compounds to treat this malignancy. Most of the current strategies to fight cancer implicate the use of compounds acting on DNA damage checkpoints, non-receptor tyrosine kinases activities, regulators of the hedgehog signaling pathways, and metabolic adaptations placed in cancer. In the last decade, the finding of a lipid peroxidation increase linked to 15-lipoxygenases isoform 1 (15-LOX-1) activity stimulation has been found in specific successful treatments against cancer. This discovery contrasts with the production of other lipid oxidation signatures generated by stimulation of other lipoxygenases such as 5-LOX and 12-LOX, and cyclooxygenase (COX-2) activities, which have been suggested as cancer biomarkers and which inhibitors present anti-tumoral and antiproliferative activities. These findings support the previously proposed role of lipid hydroperoxides and their metabolites as cancer cell mediators. Depletion or promotion of lipid peroxidation is generally related to a specific production source associated with a cancer stage or tissue in which cancer originates. This review highlights the potential therapeutical use of chemical derivatives to stimulate or block specific cellular routes to generate lipid hydroperoxides to treat this disease.

"Azole" as privileged heterocycle for targeting the inducible cyclooxygenase enzyme

An over-expression of COX-2 isoenzyme belonging to the Cyclooxygenase Enzyme Family triggers the overproduction of pro-inflammatory prostaglandins that instigate the development of chronic inflammation and related disorders. Hence, the rationally designed drugs for mitigating over-activity of COX-2 isoenzyme play a regulatory role toward the alleviation of the progression of these disorders. However, a selective COX-2 inhibition chemotherapy prompts several side effects that necessitate the identification of novel molecular scaffolds for deliberating state-of-the-art drug designing strategies. The heterocyclic "azole" scaffold, being polar and hydrophilic, possesses remarkable physicochemical advantages for designing physiologically active molecules capable of interacting with a wide range of biological components, including enzymes, peptides, and metabolites. The substituted derivatives of azole nuclei enable a comprehensive SAR analysis for the appraisal of bioactive profile of the deliberated molecules for obtaining the rationally designed compounds with prominent activities. The comprehensive SAR analysis readily prompted the identification of Y-shaped molecules and the eminence of bulkier group for COX-2 selective inhibition. This review presents an epigrammatic collation of the pharmacophore-profile of the chemotherapeutics based on azole motif for a selective targeting of the COX-2 isoenzyme.

Computational analysis of eugenol inhibitory activity in lipoxygenase and cyclooxygenase pathways

Chronic inflammation is triggered by numerous diseases such as osteoarthritis, Crohn's disease and cancer. The control of the pro-inflammatory process can prevent, mitigate and/or inhibit the evolution of these diseases. Therefore, anti-inflammatory drugs have been studied as possible compounds to act in these diseases. This paper proposes a computational analysis of eugenol in relation to aspirin and diclofenac and analyzing the ADMET profile and interactions with COX-2 and 5-LOX enzymes, important enzymes in the signaling pathway of pro-inflammatory processes. Through the analysis of ADMET in silico, it was found that the pharmacokinetic results of eugenol are similar to NSAIDs, such as diclofenac and aspirin. Bioinformatics analysis using coupling tests showed that eugenol can bind to COX-2 and 5-LOX. These results corroborate with different findings in the literature that demonstrate anti-inflammatory activity with less gastric irritation, bleeding and ulcerogenic side effects of eugenol. The results of bioinformatics reinforce studies that try to propose eugenol as an anti-inflammatory compound that can act in the COX-2/5-LOX pathways, replacing some NSAIDs in different diseases.

Specificity Distorted: Chemical Induction of Biological Paracatalysis

We define paracatalysis as the acceleration of a reaction that appears abnormal or nonphysiological. With the high specificity of enzymes, side reactivity of this kind is typically negligible. However, enzyme paracatalysis can be amplified to levels that are biologically significant through interactions with a special class of small molecule "antagonist", here termed a paracatalytic inducer. Compounds with this unusual mode of action tend to be natural products, identified by chance through phenotypic screens. In this Perspective, we suggest two general types of paracatalytic inducer. The first type promotes substrate ambiguity, where the enzyme's ground state selectivity is compromised, enabling the transformation of non-native substrates. The second type involves transition state ambiguity, where the paracatalytic inducer changes the enzyme's interactions with the activated substrate, giving rise to non-native bond making. Although they are unusual, small molecules that induce paracatalysis have established value as hypothesis-generating probes and a few substances, i.e., aspirin and the aminoglycosides, have proven to be translatable as medicines.

In silico characterisation of olive phenolic compounds as potential cyclooxygenase modulators. Part 2

Non-steroidal anti-inflammatory drugs (NSAIDs) are commonly used to reduce pain, and function by targeting cyclooxygenase (COX) enzymes to inhibit the production of prostaglandins that facilitate inflammation. Since oleocanthal derived from Olea europaea is known to inhibit COX, we sought to characterise novel olive compounds with COX inhibitory activity using in silico techniques. Following on from part 1 of this study which identified 1-oleyltyrosol (1OL) and ligstroside derivative 2 (LG2) with COX inhibitory potential, the mechanisms of COX interactions by these selected compounds were further examined using molecular dynamics (MD) simulations. Classical MD simulations were carried out on COX-1 and COX-2 complexed with 1OL and LG2 to determine the stability and protein backbone fluctuation. Protein dynamics were examined using essential dynamics methods and network analysis, which identified that the N-terminal epidermal growth factor-like domain and membrane bound domains of COX-1 and -2 exhibited altered motions when ligands were bound. Distinct dynamical modules were identified, and that COX-2 inter-residue communications were more sensitive to ligand binding compared to COX-1. The use of various network metrics presents a novel approach in the characterisation of network behaviour of different ligands. It is proposed that inter-residue network metrics provide additional measures of the potential bioactivity of ligands, which may form a useful adjunct to conventional direct predictions of binding affinity, in determining the efficacy of potential small-molecule inhibitors. Overall, this two-part study characterises anti-inflammatory effects of low dosage dietary COX inhibitors, and provides a possible avenue for the development of therapeutics in inflammatory diseases.

In silico characterisation of olive phenolic compounds as potential cyclooxygenase modulators. Part 1

Non-steroidal anti-inflammatory drugs (NSAIDs) are widely used to reduce pain. These target cyclooxygenase (COX) enzymes which produce inflammatory mediators. Adverse effects associated with the use of traditional NSAIDs have led to a rise in the development of alternative therapies. Derived from Olea Europaea, olive oil is a main component of the Mediterranean diet, containing phenolic compounds that contribute to its antioxidant and anti-inflammatory properties. It has previously been found that oleocanthal, a phenolic compound derived from the olive, had similar effects to ibuprofen, a commonly used NSAID. There is an abundance of olive phenolic compounds that have yet to be investigated for their anti-inflammatory properties. In this study, it was sought to identify potential olive-derived compounds with the ability to inhibit COX enzymes, and study the mechanisms using in silico approaches. Molecular docking was employed to determine the COX inhibitory potential of an olive phenolic compound library. From docking, it was determined that 1-oleyltyrosol (1OL) and ligstroside derivative 2 (LG2) demonstrated the greatest binding affinity to both COX-1 and COX-2. Interactions with these compounds were further examined using molecular dynamics simulations. The residue contributions to binding free energy were computed using Molecular Mechanics-Poisson Boltzmann Surface Area (MM-PBSA) methods, revealing that residues Leu93, Val116, Leu352, and Ala527 in COX-1 and COX-2 were key determinants of potential inhibition. Along with part 2 of this study, this work aims to identify and characterise novel phenolic compounds which may possess COX inhibitory properties.

The enzymology of human eicosanoid pathways: the lipoxygenase branches

Eicosanoids are short-lived derivatives of polyunsaturated fatty acids that serve as autocrine and paracrine signaling molecules. They are involved numerous biological processes of both the well state and disease states. A thorough understanding of the progression the disease state and homeostasis of the well state requires a complete evaluation of the systems involved. This review examines the enzymology for the enzymes involved in the production of eicosanoids along the lipoxygenase branches of the eicosanoid pathways with particular emphasis on those derived from arachidonic acid. The enzymatic parameters, protocols to measure them, and proposed catalytic mechanisms are presented in detail.

Curcumin analogs as the inhibitors of TLR4 pathway in inflammation and their drug like potentialities: a computer-based study

Toll-like receptor 4 (TLR4) pathway is one of the major pathways that mediate the inflammation in human body. There are different anti-inflammatory drugs available in the market which specifically act on different signaling proteins of TLR4 pathway but they do have few side effects and other limitations for intended use in human body. In this study, Curcumin and its different analogs have been analyzed as the inhibitors of signaling proteins, i.e. Cycloxygenase-2 (COX-2), inhibitor of kappaβ kinase (IKK) and TANK binding kinase-1 (TBK-1) of TLR4 pathway using different computational tools. Initially, three compounds were selected for respective target based on free binding energy among which different compounds were reported to have better binding affinity than commercially available drug (control). Upon continuous computational exploration with induced fit docking (IFD), 6-Gingerol, Yakuchinone A and Yakuchinone B were identified as the best inhibitors of COX-2, IKK, and TBK-1 respectively. Then their drug-like potentialities were analyzed in different experiments where they were also predicted to perform well. Hopefully, this study will uphold the efforts of researchers to identify anti-inflammatory drugs from natural sources.

Extrapolation of hydroxytyrosol and its analogues as potential anti-inflammatory agents

Discovery of potential lead molecule is a challenging, and complex process which require lots of money, patience, and manpower. Human beings are using natural products, predominantly secondary metabolites, for this purpose since ancient time and they are still working on them as a potent source for drug discovery due to their wide structural diversity. Phenolic phytochemicals such as hydroxytyrosol and tyrosol are natural antioxidant and involved in many biological disease cure. Herein, we have carried out the quantum chemical calculations for conformational analysis, geometry optimization and computation of electronic as well as optical properties of hydroxytyrosol and its analogues (1a-1k) in terms of density functional theory by using Gaussian 09 program suite. The eventual charge transfer within the molecules has been confirmed by the analysis of frontier molecular orbitals. The molecular docking studies of 1a-1k with cyclooxygenase-2 showed the noticeable binding affinity as compared to other nonsteroidal anti-inflammatory drugs viz. aspirin, naproxen and celecoxib. Computation of pharmacokinetics and pharmacological properties confirmed the lead/drug like potential of these screened molecules. Furthermore, the molecular dynamics simulation of best three docked ligands (1f, 1h and 1k)-receptor complex and their binding free energy calculations reveals that these molecules bind in the catalytic cavity of cyclooxygenase-2 and found stable during the 100 ns of simulation. Communicated by Ramaswamy H. Sarma.

Structural and Chemical Biology of the Interaction of Cyclooxygenase with Substrates and Non-Steroidal Anti-Inflammatory Drugs

Cyclooxgenases are key enzymes of lipid signaling. They carry out the first step in the production of prostaglandins, important mediators of inflammation, pain, cardiovascular disease, and cancer, and they are the molecular targets for nonsteroidal anti-inflammatory drugs, which are among the oldest and most chemically diverse set of drugs known. Homodimeric proteins that behave as allosterically modulated, functional heterodimers, the cyclooxygenases exhibit complex kinetic behavior, requiring peroxide-dependent activation and undergoing suicide inactivation. Due to their important physiological and pathophysiological roles and keen interest on the part of the pharmaceutical industry, the cyclooxygenases have been the focus of a vast array of structural studies, leading to the publication of over 80 crystal structures of the enzymes in complex with substrates or inhibitors supported by a wealth of functional data generated by site-directed mutation experiments. In this review, we explore the chemical biology of the cyclooxygenases through the lens of this wealth of structural and functional information. We identify key structural features of the cyclooxygenases, break down their active site into regional binding pockets to facilitate comparisons between structures, and explore similarities and differences in the binding modes of the wide variety of ligands (both substrates and inhibitors) that have been characterized in complex with the enzymes. Throughout, we correlate structure with function whenever possible. Finally, we summarize what can and cannot be learned from the currently available structural data and discuss the critical intriguing questions that remain despite the wealth of information that has been amassed in this field.

Calcarea carbonica treatment rescues lipopolysaccharide-induced inflammatory response in human mononuclear cells via downregulation of inducible cyclooxygenase pathway

OBJECTIVE

Prolonged use of nonsteroidal anti-inflammatory drugs is associated with severe side effects and toxicity. Therefore, we studied the anti-inflammatory role of Calcarea carbonica which had minimal toxicity at the low doses.

METHODS

THP-1 human mononuclear cells were treated with C. carbonica to evaluate the 50% cytotoxicity concentration (CC₅₀) and 50% effective concentration (EC₅₀). Cell survival was evaluated in lipopolysaccharide-stimulated C. carbonica-treated cells. Nitric oxide (NO) and tumor necrosis factor-α (TNF-α) were measured to evaluate the anti-inflammatory activity of C. carbonica. Cyclooxygenase-2 (COX-2) protein expression was determined by Western blotting analysis, and the interaction of C. carbonica with the COX-2 protein was evaluated using molecular docking simulation.

RESULTS

The CC₅₀ and EC₅₀ of C. carbonica were found to be 43.26 and 11.99 µg/mL, respectively. The cell survival assay showed a 1.192-fold (P = 0.0129), 1.443-fold (P = 0.0009) and 1.605-fold (P = 0.0004) increase in cell survival at 24, 48 and 72 h after initiating C. carbonica treatment, respectively. C. carbonica-treated cells showed a reduction in NO levels by 2.355 folds (P = 0.0001), 2.181 folds (P = 0.0001) and 2.071 folds (P = 0.0001) at 24, 48 and 72 h, respectively. The treated cells also showed a reduction in TNF-α levels by 1.395 folds (P = 0.0013), 1.541 folds (P = 0.0005) and 1.550 folds (P = 0.0005) at 24, 48 and 72 h, respectively. In addition, a 1.193-fold reduction (P = 0.0126) in COX-2 protein expression was found in C. carbonica-treated cells. The molecular docking showed interaction of C. carbonica with the phenylalanine 367 residue present in active site of Cox-2.

CONCLUSION

C. carbonica exhibited anti-inflammatory properties in lipopolysaccharide-stimulated cells by significantly reducing NO production and TNF-α level through downregulation of the COX-2 protein. This effect is probably mediated through interaction of C. carbonica with the phenylalanine 367 residue present in active site of Cox-2.

All about pain pharmacology: what pain physicians should know

From the perspective of the definition of pain, pain can be divided into emotional and sensory components, which originate from potential and actual tissue damage, respectively. The pharmacologic treatment of the emotional pain component includes antianxiety drugs, antidepressants, and antipsychotics. The anti-anxiety drugs have anti-anxious, sedative, and somnolent effects. The antipsychotics are effective in patients with positive symptoms of psychosis. On the other hand, the sensory pain component can be divided into nociceptive and neuropathic pain. Non-steroidal anti-inflammatory drugs (NSAIDs) and opioids are usually applied for somatic and visceral nociceptive pain, respectively; anticonvulsants and antidepressants are administered for the treatment of neuropathic pain with positive and negative symptoms, respectively. The NSAIDs, which inhibit the cyclo-oxygenase pathway, exhibit anti-inflammatory, antipyretic, and analgesic effects; however, they have a therapeutic ceiling. The adverse reactions (ADRs) of the NSAIDs include gastrointestinal problems, generalized edema, and increased bleeding tendency. The opioids, which bind to the opioid receptors, present an analgesic effect only, without anti-inflammatory, antipyretic, or ceiling effects. The ADRs of the opioids start from itching and nausea/vomiting to cardiovascular and respiratory depression, as well as constipation. The anticonvulsants include carbamazepine, related to sodium channel blockade, and gabapentin and pregabalin, related to calcium blockade. The antidepressants show their analgesic actions mainly through inhibiting the reuptake of serotonin or norepinephrine. Most drugs, except NSAIDs, need an up-dose titration period. The principle of polypharmacy for analgesia in case of mixed components of pain is increasing therapeutic effects while reducing ADRs, based on the origin of the pain.

Structural modification of aspirin to design a new potential cyclooxygenase (COX-2) inhibitors

Aspirin (Asp) is one of the most important and ancient member of nonsteroidal anti-inflammatory drugs (NSAID), commonly used in medication of fever, pain and inflammation. It can inhibit the synthesis of prostaglandin by blocking the cyclooxygenase (COX). Attempts have been taken to analyze aspirin together with some of its modified derivatives applying quantum mechanical calculations in order to compare their physicochemical and biochemical properties. Density functional theory (DFT) with B3LYP/6-31G (d, p) basis set has been employed to elucidate their thermal, molecular orbital, equilibrium geometrical properties in gas phase. Molecular docking and nonbonding interactions have been performed against human cyclooxygenase-2 protein 5F1A to investigate the binding affinity and mode(s) of newly designed aspirin derivatives. ADMET prediction has been utilized to compare the absorption, metabolism, and carcinogenic properties of new derivatives with parent drug (Asp). Thermal and geometrical results support the thermochemical stability and equilibrium geometry of all the structures. From the molecular docking simulation, most of the derivatives exhibited better binding affinity than parent drug (Asp) with the receptor protein (5F1A). ADMET prediction disclosed the improved pharmacokinetic properties with lower acute oral toxicity of some derivatives. Based on quantum chemical, molecular docking and ADMET analysis, this investigation can be useful to understand the physicochemical and biochemical/biological activities of Asp and its modified derivatives to search a new antipyretic analgesic drug.

An Improved Synthesis of Key Intermediate to the Formation of Selected Indolin-2-Ones Derivatives Incorporating Ultrasound and Deep Eutectic Solvent (DES) Blend of Techniques, for Some Biological Activities and Molecular Docking Studies

We have developed a new idea to synthesize a key intermediate molecule by utilizing deep eutectic solvent (DES) and ultrasound in a multistep reaction to ensure process cost-effectiveness. To confirm the stability of reagents with DES, electronic energies were calculated at the B3LYP/6-31+G(d,p) level of theory. DES stabilized the reagents mainly due to strong intermolecular hydrogen bonding. Key intermediate (3) and final compounds (4a-n) were synthesized in a higher yield of 95% and 80%-88%, respectively. Further, final compounds (4a-n) were assessed for their anti-inflammatory, analgesic, ulcerogenic, and lipid peroxidation. The compounds 4f, 4g, 4j, 4l, and 4m showed good anti-inflammatory activity, while 4f, 4i, and 4n exhibited very good analgesic activity as compared to the standard drug. The ulcerogenicity of selected compounds was far less than the indomethacin. The ligands had also shown a good docking score (4f = -6.859 kcal/mol and 4n = -7.077 kcal/mol) as compared to control indomethacin (-6.109 kcal/mol) against the target protein COX-2. These derivatives have the potential to block this enzyme and can be used as NSAID. The state-of-art DFT theory was used to validate the lipid peroxidation mechanism of the active compounds which was in good agreement with the variations of BDEs and IP of the tested compounds.

Patent highlights, August-September 2019

A snapshot of recent noteworthy developments in the patent literature of relevance to pharmaceutical and medical research and development.

The Biosynthesis of Enzymatically Oxidized Lipids

Enzymatically oxidized lipids are a specific group of biomolecules that function as key signaling mediators and hormones, regulating various cellular and physiological processes from metabolism and cell death to inflammation and the immune response. They are broadly categorized as either polyunsaturated fatty acid (PUFA) containing (free acid oxygenated PUFA "oxylipins", endocannabinoids, oxidized phospholipids) or cholesterol derivatives (oxysterols, steroid hormones, and bile acids). Their biosynthesis is accomplished by families of enzymes that include lipoxygenases (LOX), cyclooxygenases (COX), cytochrome P450s (CYP), and aldo-keto reductases (AKR). In contrast, non-enzymatically oxidized lipids are produced by uncontrolled oxidation and are broadly considered to be harmful. Here, we provide an overview of the biochemistry and enzymology of LOXs, COXs, CYPs, and AKRs in humans. Next, we present biosynthetic pathways for oxylipins, oxidized phospholipids, oxysterols, bile acids and steroid hormones. Last, we address gaps in knowledge and suggest directions for future work.

Structure-Activity Relationships of Pentacyclic Triterpenoids as Inhibitors of Cyclooxygenase and Lipoxygenase Enzymes

Pentacyclic triterpenes may be active agents and provide a rich natural resource of promising compounds for drug development. The inhibitory activities of 29 natural oleanane and ursane pentacyclic triterpenes were evaluated against four major enzymes involved in the inflammatory process: 5-LOX, 15-LOX-2, COX-1, and COX-2. It was found that 3-O-acetyl-β-boswellic acid potently inhibited human 15-LOX-2 (IC₅₀ = 12.2 ± 0.47 μM). Analysis of the structure-activity relationships revealed that the presence of a hydroxy group at position 24 was beneficial in terms of both 5-LOX and COX-1 inhibition. Notably, the introduction of a carboxylic acid group at position 30 was important for dual 5-LOX/COX inhibitory activity; furthermore, its combination with a carbonyl group at C-11 considerably increased 5-LOX inhibition. Also, the presence of an α-hydroxy group at C-2 or a carboxylic acid group at C-23 markedly suppressed the 5-LOX activity. The present findings reveal that the types and configurations of polar moieties at positions C-2, -3, -11, -24, and -30 are important structural aspects of pentacyclic triterpenes for their potential as anti-inflammatory lead compounds.

The In Silico Characterization of a Salicylic Acid Analogue Coding Gene Clusters in Selected Pseudomonas fluorescens Strains

BACKGROUND

The microbial genome sequences provide solid in silico framework for interpretation of their drug-like chemical scaffolds biosynthetic potentials. Pseudomonas fluorescens strains are metabolically versatile and producing therapeutically important natural products.

OBJECTIVES

The key objective of the present study was to mine the publically available data of P. fluorescens strains genomes for putative drug-like metabolites identification.

MATERIALS AND METHODS

We implemented the computational biology resources of AntiSMASH and BAGEL3 for the secondary metabolites prediction from P. fluorescens strains genome sequences. The predicted secondary metabolites were evaluated using drug discovery chemoinformatics resources, like Drugbank database search and molecular docking inspection.

RESULTS

The analyses unveiled a wide array of chemical scaffolds biosynthesis in different P. fluorescens strains. Subsequently, the drug-like potential evaluation of these metabolites identified few strains, including P. fluorescens PT14, P. fluorescens A5O6, and P. fluorescens FW300-N2E3 that harbor the biosynthetic gene clusters for salicylic acid-like metabolite biosynthesis. The molecular docking inspection of this metabolite against human cyclooxygenase and aldo-keto reductase targets revealed its feasible inhibitory potentials like other salicylate compounds.

CONCLUSION

The computational biology and drug discovery analyses identified different gene clusters in P. fluorescens genomes coding for salicylic acid-like chemotypes biosynthesis. These gene clusters may worthy to target through metabolic engineering for the massive production of salicylates-like chemical scaffolds from microbial resources.

Clinical use of low-dose aspirin for elders and sensitive subjects

The use of low-dose aspirin (LDA) has been a common preventive measure to reduce the risk of cardiovascular events. This is attributed to aspirin’s ability to inhibit platelet activation. On the other hand, the use of LDA in human subjects has been associated with the development of gastrointestinal injuries like ulcer and bleeding, especially for those sensitive subjects such as elder human subjects. This opinion review will summarize the recent clinical reports regarding the use of LDA and the development of gastrointestinal conditions in China. Based on these reports, it seems that the use of LDA is commonly associated with gastrointestinal injuries, and stopping its use leads to recovery in elderly subjects. Therefore, we would like to suggest that gastroduodenal health and conditions should be seriously taken into consideration when LDA is recommended to the elderly, or other alternative means to reduce the risk of cardiovascular events such as nutritional interventions should be suggested.

Potential of Curcumin in Skin Disorders

Curcumin is a compound isolated from turmeric, a plant known for its medicinal use. Recently, there is a growing interest in the medical community in identifying novel, low-cost, safe molecules that may be used in the treatment of inflammatory and neoplastic diseases. An increasing amount of evidence suggests that curcumin may represent an effective agent in the treatment of several skin conditions. We examined the most relevant in vitro and in vivo studies published to date regarding the use of curcumin in inflammatory, neoplastic, and infectious skin diseases, providing information on its bioavailability and safety profile. Moreover, we performed a computational analysis about curcumin's interaction towards the major enzymatic targets identified in the literature. Our results suggest that curcumin may represent a low-cost, well-tolerated, effective agent in the treatment of skin diseases. However, bypass of limitations of its in vivo use (low oral bioavailability, metabolism) is essential in order to conduct larger clinical trials that could confirm these observations. The possible use of curcumin in combination with traditional drugs and the formulations of novel delivery systems represent a very promising field for future applicative research.

Arg-513 and Leu-531 Are Key Residues Governing Time-Dependent Inhibition of Cyclooxygenase-2 by Aspirin and Celebrex

Aspirin and Celebrex are well-known time-dependent inhibitors of the cyclooxygenases (COX). Molecular dynamics simulations suggest that Arg-513 and Leu-531 contribute to the structural mechanisms of COX inhibition. We used mutagenesis and functional analyses to characterize how substitutions at these positions influence time-dependent inhibition by aspirin and Celebrex. We show that substitutions of Leu-531 with asparagine and phenylalanine significantly attenuate time-dependent inhibition of COX-2 by these drugs. The introduction of side chain bulk, rigidity, and charge would disrupt the formation of the initial noncovalent complex, in the case of aspirin, and the "high-affinity" binding state, in the case of Celebrex. Substitution of Arg-513 with histidine (the equivalent residue in COX-1) resulted in a 2-fold potentiation of aspirin inhibition, in support of the hypothesis that the presence of histidine in COX-1 lowers the activation barrier associated with the formation of the initial noncovalent enzyme-inhibitor complex. As a corollary, we previously hypothesized that the flexibility associated with Leu-531 contributes to the binding of arachidonic acid (AA) to acetylated COX-2 to generate 15R-hydroxyeicosatetraenoic acid (15R-HETE). We determined the X-ray crystal structure of AA bound to Co³⁺-protoporphyrin IX-reconstituted V349I murine COX-2 (muCOX-2). V349I muCOX-2 was utilized as a surrogate to trap AA in a conformation leading to 15R-HETE. AA binds in a C-shaped pose, facilitated by the rotation of the Leu-531 side chain. Ile-349 is positioned to sterically shield antarafacial oxygen addition at carbon-15 in a manner similar to that proposed for the acetylated Ser-530 side chain.

Genetic polymorphisms analysis of pharmacogenomic VIP variants in Bai ethnic group from China

Background

The pharmacogenomics study has been widely used for the study of very important pharmacogenetic (VIP) variants among different ethnic groups. However, there is little known about the pharmacogenomics information regarding Bai family. Our study aimed to screen the polymorphism of the VIP gene in Bai nationality.

Methods

We genotyped 81 VIP variants (selected from the PharmGKB database) in the Bai population and then compared them to the other 11 major HapMap populations by chi‐square test, structure and F‐statistics (Fst) analysis.

Results

Our results indicated that rs20417 (PTGS2), rs4148323 (UGT1A), and rs1131596 (SLC19A1) were most different in Bai compared with most of the 11 populations from the HapMap data set. Furthermore, population structure and F‐statistics (Fst) analysis also demonstrated that the Bai population has the closest genetic relationship with Han Chinese in Beijing, China (CHB), followed by Japanese in Tokyo, Japan (JPT), and the farthest population from the Yoruba in Ibadan, Nigeria (YRI).

Conclusions

Our study not only presented the genotype frequency difference between the selected population of the Bai population and the other 11 populations, but also showed that the Bai population is most similar to the CHB populations, followed by JPT. These findings would contribute to the development of individualized medicine for the Bai population.

Synthesis, Anti-inflammatory, Antimicrobial Potential and Molecular Docking Studies of 4,5-Disubstituted-1,2,4-Triazole Thioacetate Derivatives

Background:

In the present study synthesis and biological assessment of nine new ethyl [(4,5-disubstituted- 4H-1,2,4-triazol-3-yl)sulfanyl]acetate derivatives 2(a-i) is performed.

Methods:

The title compounds were characterized by their analytical and spectral data. All the synthesized compounds were screened for their in vivo anti-inflammatory activity using carrageenaninduced rat paw oedema method and in vitro antimicrobial activity. All the compounds exhibited good anti-inflammatory activity; especially compound 2h produced the maximum effect i.e., 62.5 % comparable to that of standard, diclofenac. The antimicrobial screening results indicated that some of the newly synthesized compounds showed good antibacterial activity, especially against Escherichia coli.

Results:

All the synthesized thioacetate derivatives of triazoles were also studied for their interactions with the enzymes COX-I and COX-II, two important targets of inflammation pathway, through docking analysis. All the compounds showed good binding affinities with both the enzymes with a maximum value of -8.1 for 2e kcal/mol against COX-I.

Conclusion:

Docking analysis predicted that our compounds reduce inflammation nonselectively by inhibiting both COX-I and COX-II of inflammatory pathway just like other nonselactive NSAIDS.

Antitussive and Anti-inflammatory Dual-active Agents Developed from Natural Product Lead Compound 1-Methylhydantoin

Natural products play an important role in drug discovery. This work employed a natural product 1-methylhydantoin as the lead compound to develop novel dual-active drugs. 1-Methylhydantoin was isolated from Oviductus Ranae, which is a traditional Chinese medicine that has been used for tussive and inflammation treatment for a long time. An in silico study screened the more active 1-methylhydantoin derivatives. Antitussive assessment indicated that the newly synthesized agent had similar bioactivity with the natural product. An anti-inflammatory model used xylene induced ear edema model. At the same dosage (100 mg/Kg), the newly prepared agent had an inhibition rate 53.18% which was much higher than that of the lead compound (22.69%). The results might be ascribed to the cyclooxygenases-1 (COX-1) and cyclooxygenases-2 (COX-2) selectivity, and the fitness of the compound, and the binding pocket. The anti-particulate matter (PM 2.5) acute pneumonia was evaluated through an in vivo model constructed by nasal instillation with PM 2.5 suspension. The results of the above models suggested that this novel agent had remarkable antitussive, anti-inflammatory, and anti-PM 2.5 acute pneumonia activities.

Engineered Substrate for Cyclooxygenase-2: A Pentapeptide Isoconformational to Arachidonic Acid for Managing Inflammation

Beyond the conventional mode of working of anti-inflammatory agents through enzyme inhibition, herein, COX-2 was provided with an alternate substrate. A proline-centered pentapeptide isoconformational to arachidonic acid, which exhibited appreciable selectivity for COX-2, overcoming acetic acid- and formalin-induced pain in rats to almost 80%, was treated as a substrate by the enzyme. Remarkably, COX-2 metabolized the pentapeptide into small fragments consisting mainly of di- and tripeptides that ensured the safe breakdown of the peptide under in vivo conditions. The kinetic parameter K_cat/K_m for COX-2-mediated metabolism of the peptide (6.3 × 10⁵ M^-1 s^-1) was quite similar to 9.5 × 10⁵ M^-1 s^-1 for arachidonic acid. Evidenced by the molecular dynamic studies and the use of Y385F COX-2, it was observed that the breakage of the pentapeptide has probably been taken place through H-bond activation of the peptide bond by the side chains of Y385 and S530.

A seven-step plan for becoming a moderately rich and famous biochemist

Omega-6 polyunsaturated fatty acids were identified as essential nutrients in 1930. Their essentiality is largely due to their function as prostaglandin (PG) precursors. I spent most of my career in biochemistry determining how PG biosynthesis is regulated. PGs are lipid mediators formed in response to certain circulating hormones and cytokines. PGs act near their sites of synthesis to signal neighboring cells to coordinate their responses (e.g. when platelets interact with blood vessels). The committed step in PG synthesis is the conversion of a 20-carbon omega-6 fatty acid called arachidonic acid to prostaglandin endoperoxide H₂ (PGH₂). Depending on the tissue and the hormone or cytokine stimulus, this reaction is catalyzed by either cyclooxygenase-1 or cyclooxygenase-2 (COX-1 or COX-2). Once formed, PGH₂ is converted, again depending on the context, to one of several downstream PG subtypes that act via specific G protein-coupled receptors. Nonsteroidal anti-inflammatory drugs (e.g. aspirin, ibuprofen, and naproxen) block PG synthesis by inhibiting COX-1 and COX-2. COX-2 is also inhibited by COX-2-selective inhibitors. Inhibition of COX-1 by low-dose aspirin prevents thrombosis. COX-2 inhibition reduces inflammation and pain. Investigating the mysteries of COXs anchored my scientific career. I attribute my successes to the great good fortune of having been surrounded by people who helped me make the most of my talents. I have written this reflection in a light-hearted fashion as a self-help essay, while highlighting the people and factors that most impacted me during my upbringing and then during my maturation and evolution as a biochemist.