Flavonoids as noncompetitive inhibitors of Dengue virus NS2B-NS3 protease: Inhibition kinetics and docking studies

NS2B-NS3 is a serine protease of the Dengue virus considered a key target in the search for new antiviral drugs. In this study flavonoids were found to be inhibitors of NS2B-NS3 proteases of the Dengue virus serotypes 2 and 3 with IC50 values ranging from 15 to 44 μM. Agathisflavone (1) and myricetin (4) turned out to be noncompetitive inhibitors of dengue virus serotype 2 NS2B-NS3 protease with Ki values of 11 and 4.7 μM, respectively. Docking studies propose a binding mode of the flavonoids in a specific allosteric binding site of the enzyme. Analysis of biomolecular interactions of quercetin (5) with NT647-NHS-labeled Dengue virus serotype 3 NS2B-NS3 protease by microscale thermophoresis…

Convergent synthesis and preliminary biological evaluations of the stilbenolignan (±)-aiphanol and various congeners

Treatment of an equimolar mixture of stilbene 7 and cinnamyl alcohol 8 with silver carbonate in acetone–benzene afforded a ca. 2 : 1 : 2 : 1 mixture of the stilbenolignan (±)-aiphanol (1) and congeners 2–4 each of which show significant anti-angiogenic and COX-2 inhibitory properties.

COX-2 inhibition and pain management: a review summary

Cyclooxygenase-2 selective inhibitors have long been regarded as potent anti-inflammatory drugs for the treatment of arthritis, osteoarthritis and dysmenorrhea. The reports of cardiovascular risk and the subsequent withdrawal of rofecoxib, and recently valdecoxib, has called the therapeutic potential of coxibs into question. Currently, according to the latest decisions of the US Food and Drug Administration and European Medicines Agency, the approval of valdecoxib has been refused for 1 year due to an increased rate of cardiovascular risks and serious skin reactions. There are restrictions concerning the use of all other coxibs. The short-time use of coxibs, however, in anti-inflammatory tr…

Synthesis and Evaluation of a Novel Series of Pyrrolizine Derivatives as Dual Cyclooxygenase-1 and 5-Lipoxygenase Inhibitors

The aim of our study was to investigate structure activity relationship following the replacement of the 6-phenyl substituent at the 6,7-diaryl-2,3-dihydropyrrolizine template by various heteroaromatic residues. In this context we developed a new, efficient, and highly sensitive test method for the screening of dual cyclooxygenase-1 (COX-1) and 5-lipoxygenase (5-LOX) inhibitors. We used human platelets as a source of COX-1 and human PMNLs as a source of 5-LOX. Both cell types were isolated from the same volume of blood. PGE2 and LTB4 respectively were determined by highly selective and sensitive ELISA kits, using monoclonal antibodies. For a single determination at most 0.5 mL whole blood i…

Proline-Based Allosteric Inhibitors of Zika and Dengue Virus NS2B/NS3 Proteases

The NS2B/NS3 serine proteases of the Zika and Dengue flaviviruses are attractive targets for the development of antiviral drugs. We report the synthesis and evaluation of a new, proline-based compound class that displays allosteric inhibition of both proteases. The structural features relevant for protease binding and inhibition were determined to establish them as new lead compounds for flaviviral inhibitors. Based on our structure-activity relationship studies, the molecules were further optimized, leading to inhibitors with submicromolar IC50 values and improved lipophilic ligand efficiency. The allosteric binding site in the proteases was probed using mutagenesis and covalent modificati…

ChemInform Abstract: Regioisomeric 3-, 4-, and 5-Aminomethylisoxazoles: Synthesis and Muscarinic Activity.

New aziridine-based inhibitors of cathepsin L-like cysteine proteases with selectivity for the Leishmania cysteine protease LmCPB2.8

Abstract In the present work a series of aziridine-2,3-dicarboxylate inhibitors of papain-like cysteine proteases was designed, synthesized and tested. The compounds displayed selectivity for the parasitic protozoon Leishmania mexicana cathepsin L-like cysteine protease LmCPB2.8. The computational methods of homology modelling and molecular docking predicted some significant differences in the S2 pocket of LmCPB2.8 and cruzain, a related enzyme from Trypanosoma cruzi. Due to the presence of Tyr209 in LmCPB2.8 rather than Glu208 in cruzain sterically demanding, lipophilic ester groups (inhibitor 7d, 9d, 12d and 14d) are predicted to occupy the S2 pocket of the Leishmania protease, but do not…

Nonsteroidal Antiinflammatory Agents, XVIII: C-5 Functionalized 6,7-Diphenyl-2,3-dihydro-1H-pyrrolizines as Inhibitors of Bovine Cyclooxygenase and 5-Lipoxygenase

6-(4-Chlorophenyl)-7-phenyl-2,3-dihydro-1H-pyrrolizines with functional groups at position 5 of the heterocyclic moiety were synthesized and tested. To determine their antiinflammatory activity bovine blood was used as enzyme source for the cyclooxygenase and 5-lipoxygenase, respectively. The iminoxy acetic acid derivative and the iminotetrazole selectively inhibit the 5-lipoxygenase, all the other compounds show medium or low affinity to the active sites of cyclooxygenase and 5-lipoxygenase. In general all compounds inhibit 5-lipoxygenase more effectively than cyclooxygenase. Concerning the inhibition of 5-lipoxygenase the most active compounds found are equipotent to the corresponding pro…

ChemInform Abstract: Cyclooxygenase Inhibitors - Current Status and Future Prospects

Prostaglandins are formed from arachidonic acid by the action of cyclooxygenase and subsequent downstream synthetases. Two closely related forms of the cyclooxygenase have been identified which are now known as COX-1 and COX-2. Both isoenzymes transform arachidonic acid to prostaglandins, but differ in their distribution and their physiological roles. Meanwhile, the responsible genes and their regulation have been clarified. COX-1, the pre-dominantly constitutive form of the enzyme, is expressed throughout the body and performs a number of homeostatic functions such as maintaining normal gastric mucosa and influencing renal blood flow and platelet aggregation. In contrast, the inducible for…

ChemInform Abstract: Nonsteroidal Antiinflammatory Agents. Part 18. C-5 Functionalized 6,7- Diphenyl-2,3-dihydro-1H-pyrrolizines as Inhibitors of Bovine Cyclooxygenase and 5-Lipoxygenase.

The pyrrole moiety as a template for COX-1/COX-2 inhibitors

Aroyl- and thiophene-substituted pyrrole derivatives have been synthesized as a new class of COX-1/COX-2 inhibitors. The inhibition of COX-1 was evaluated in a biological system using bovine PMNLs as the enzyme source, whereas LPS-stimulated human monocytes served as the enzyme source for inducible COX-2. The determination of the concentration of arachidonic acid metabolites was performed by HPLC for COX-1 and RIA for COX-2. Variation of the substitution pattern led to a series of active compounds which showed inhibition for COX-1 and COX-2. Structural requirements for the development of COX-1/COX-2 inhibitors are discussed.

Neue Antiepileptika in der Entwicklung. Substanzen mit neuen Wirkmechanismen

Unbestritten ist, dass sich durch den Einsatz von Antiepileptika der 2. Generation die Situation fur Epilepsiepatienten entscheidend verbessert hat. Dennoch bleibt ein Patientenklientel, bei dem keine ausreichende Anfallskontrolle erreicht wird, das therapierefraktar ist oder im Verlauf der Behandlung wird. Weiterentwicklungen von AEDs aus der 2. Generation (“follow-up compounds”) bzw. Wirkstoffe mit neuen Strukturen und Wirkmechanismen konnten zukunftig diese Lucke fullen.

ChemInform Abstract: Non-Steroidal Antiinflammatory Agents. Part 19. E-2-Pyrrolizin-5-yl Acrylic Acids as Potent Dual or Selective Inhibitors of Bovine Cyclooxygenase and 5-Lipoxygenase.

Non-steroidal Anti-inflammatory Agents, Part 19:E-2-Pyrrolizin-5-yl Acrylic Acids as Potent Dual or Selective Inhibitors of Bovine Cyclooxygenase and 5-Lipoxygenase

The pyrrolizinyl substituted acrylic acid derivatives represent another class of dual and selective inhibitors of cyclooxygenase and 5-lipoxygenase. By modifying their substitution pattern at the phenyl moiety of C-6 the balance between the activity against cyclooxygenase and against 5-lipoxygenase can be shifted. Structure-activity relationships are discussed. Compound 6k is the most potent and well-balanced dual inhibitor of both enzymes, while the highest selectivity of lipoxygenase inhibition was found for 6j. The activity and selectivity of compounds with an additional sulfur moiety depend on the oxidation status of this atom, giving an indication of the discussed coupling between pero…

ChemInform Abstract: 1-Pyrrolines (3,4-Dihydro-2H-pyrroles) as a Template for New Drugs

Cyclooxygenase inhibitors – current status and future prospects

Prostaglandins are formed from arachidonic acid by the action of cyclooxygenase and subsequent downstream synthetases. Two closely related forms of the cyclooxygenase have been identified which are now known as COX-1 and COX-2. Both isoenzymes transform arachidonic acid to prostaglandins, but differ in their distribution and their physiological roles. Meanwhile, the responsible genes and their regulation have been clarified. COX-1, the pre-dominantly constitutive form of the enzyme, is expressed throughout the body and performs a number of homeostatic functions such as maintaining normal gastric mucosa and influencing renal blood flow and platelet aggregation. In contrast, the inducible for…

Investigations Concerning the Correlation of COX-1 Inhibitory and Hydroxyl Radical Scavenging Activity

The aim was to study the COX-1 inhibiting efficacy in context with hydroxyl radical scavenging properties of compounds bearing a carboxylic acid and ester function, respectively. In general, the acids are more potent radical scavengers than the corresponding esters but there is no clear correlation with their COX-1 inhibiting potencies. A feasible scavenging mechanism of carboxylic acids is discussed.

Simultaneous determination of olanzapine, clozapine and demethylated metabolites in serum by on-line column-switching high-performance liquid chromatography.

An automated method for simultaneous routine quantification of the antipsychotic drugs clozapine, olanzapine and their demethylated metabolites is described. The method included adsorption on a cyanopropyl (CPS) coated clean-up column (10 microm; 10 x 2.0 mm I.D.), washing off interfering serum constituents to waste, and separation on C18 ODS Hypersil reversed phase material (5 microm; 250 x 4.6 mm I.D.) using acetonitrile-water-tetramethylethylenediamine (37:62.6:0.4, v/v/v) adjusted to pH 6.5 with concentrated acetic acid. UV-detection was performed at 254 nm. The limit of quantification was 10-20 ng/ml. Relative day to day standard variations ranged between 4.5 and 13.5%. The method is s…

Novel Insights and Therapeutical Applications in the Field of Inhibitors of COX-2

The discovery of the two isoenzymes COX-1 and COX-2 and the knowledge of their function, localisation and regulation has initiated the development of COX-2 selective inhibitors (coxibs). Inducible COX-2 at the peripheral site of inflammation has been detected in the early 1990s, the involvement of recently detected spinal COX-2 has led to new insights into mechanisms of pain and may explain analgesic and antipyretic properties of COX-2 selective inhibitors. The coxibs rofecoxib and celecoxib have been introduced into therapy and seem to offer some advantages over the classical non-selective NSAIDs. The search for new COX-2 inhibitors is going on, the development of etoricoxib and lumiracox…

Natural products as inhibitors of recombinant cathepsin L of Leishmania mexicana.

Cysteine proteinases (cathepsins) from Leishmania spp. are promising molecular targets against leishmaniasis. Leishmania mexicana cathepsin L is essential in the parasite life cycle and a pivotal in virulence factor in mammals. Natural products that have been shown to display antileishmanial activity were screened as part of our ongoing efforts to design inhibitors against the L. mexicana cathepsin L-like rCPB2.8. Among them, agathisflavone (1), tetrahydrorobustaflavone (2), 3-oxo-urs-12-en-28-oic acid (3), and quercetin (4) showed significant inhibitory activity on rCPB2.8 with IC50 values ranging from 0.43 to 18.03 µM. The mechanisms of inhibition for compounds 1–3, which showed Ki values…

1-Pyrrolines (3,4-Dihydro-2H-pyrroles) as a Template for New Drugs

Antiepileptika – Wirkprinzipien und strukturelle Parameter. Wissenswertes zur Pharmakokinetik und Pharmakodynamik

Bereits im altesten bekannten Schrifttext der Menschheit, dem Gesetzeskodex von Hammurabi (1728 bis 1686 v. Chr.), wurde die Epilepsie erwahnt. In der Antike als “Heilige Krankheit” charakterisiert ist die Epilepsie die haufigste chronisch neurologische Erkrankung des zentralen Nervensystems. Nach aktuellen Schatzungen leiden etwa 0,4 bis 1 % der Bevolkerung an epileptischen Erkrankungen, wobei ein Drittel der Betroffenen meist junger ist als 16 Jahre.

ChemInform Abstract: The Pyrrole Moiety as a Template for COX-1/COX-2 Inhibitors.

Effect of Flavonol Derivatives on the Carrageenin-Induced Paw Edema in the Rat and Inhibition of Cyclooxygenase-1 and 5-Lipoxygenase in Vitro

Alkoxyflavonols were synthesized by the Algar-Flynn-Oyamada (AFO) cyclization of chalcones. Hydroxyflavonols were prepared by dealkylation of methoxyflavonols by refluxing in hydroiodic acid. The alkoxyflavonols 3-hydroxy-2-(2,3,4-trimethoxyphenyl)-4H-chromen-4-one (6), 2-(4-ethoxyphenyl)-3-hydroxy-4H-chromen-4-one (7), 2-(4-butoxyphenyl)-3-hydroxy-4H-chromen-4-one (10), and 2-(3-n-butoxyphenyl)-3-hydroxy-4H-chromen-4-one (11) as well as the trihydroxy derivative 3-hydroxy-2-(3,4,5-trihydroxyphenyl)-4H-chromen-4-one (18) displayed high anti-inflammatory activity in carrageenin-induced rat paw edema. Additionally, the inhibition of enzymes of the arachidonic acid cascade by the derivatives w…