New Zileuton-Hydroxycinnamic Acid Hybrids: Synthesis and Structure-Activity Relationship towards 5-Lipoxygenase Inhibition

In-silico structural studies on anti-inflammatory activity of phytocompounds from the genus Andrographis

Plant species from the genus Andrographis were used in Ayurveda and in other folklore medicines for treating ailments for centuries. In this study, we have hypothesized to evaluate the secondary metabolites as potent anti-inflammatory agents from the genus Andrographis. A library of secondary metabolites of the said genus was curated from the PubChem database and was subjected to energy minimization using UCSF Chimera software employing the AMBER force field. Initially, molecular docking was performed to evaluate the binding affinity of the curated library against the enzymes cyclooxygenase-1 (COX-1), cyclooxygenase-2 (COX-2), and 5-Lipoxygenase (5-LOX) using AutoDock Vina. This resulted in shortlisting of two metabolites Echioidinin 5-O-glucoside was bound and 5,2',6'-Trihydroxy-6,7,8-trimethoxy flavone 2'-O-glucoside with high binding affinity than standard drugs Ibuprofen and Zileuton. In addition, molecular dynamic simulation studies confirm that these compounds form relatively more stable complexes than standard drugs with the above-said enzymes. The free binding energy values using MMGBSA of the above said ligands with COX-1, COX-2, and 5-LOX were found to be -49.18 kcal/mol, -38.60 kcal/mol, and -54.27 kcal/mol respectively, Whereas the standards have -21.77 kcal/mol, -9.96 kcal/mol, and -10.29 kcal/mol. Moreover, the in-silico ADMET analysis confirms the druggability of the shortlisted compounds. Later, this work will act as a base for in-vitro and in-vivo experimental studies to validate the anti-inflammatory potential of the same.Communicated by Ramaswamy H. Sarma.

Single and multiple inhibitors of the biosynthesis of 5-, 12-, 15-lipoxygenase products derived from cinnamyl-3,4-dihydroxy-α-cyanocinnamate: Synthesis and structure-activity relationship

The involvement of lipoxygenases in various pathologies, combined with the unavailability of safe and effective inhibitors of the biosynthesis of their products, is a source of inspiration for the development of new inhibitors. Based on a structural analysis of known inhibitors of lipoxygenase products biosynthesis, a comprehensive structure-activity study was carried out, which led to the discovery of several novel compounds (16a-c, 17a) demonstrating promising potency to inhibit the biosynthesis of products of 5-, 12- and 15-LO. Compounds 16b and 16c outperformed zileuton (1), the only FDA-approved 5-LO inhibitor, as well as known inhibitors such as caffeic acid phenethyl ester (CAPE (2)) and cinnamyl-3,4-dihydroxy-α-cyanocinnamate (CDC (4)). However, the introduction of a cyano group at the α-position of the carbonyl abolished the activity. Compounds 16a and 17a also inhibited the biosynthesis of 12- and 15-LO products. Compounds 16a, 17a far surpassed baicalein, a known 12-LO inhibitor, as inhibitors of 12-LO products biosynthesis. Compound 17a and CDC (4) showed equivalent inhibition of LO products, proposing that the double bond in the ester moiety is not necessary for the inhibitory activity. The introduction of the cyano group, as in compound 17a, at the α-position of the carbonyl in compound 16a significantly reduced the inhibitory activity against the biosynthesis of 15-LO products. In addition to the interactions with residues His372 and Phe421 also found with zileuton and CAPE, compounds 16a and 16c each interact with residue His367 as shown by molecular docking. This new interaction may explain their high affinity with the 5-LO active site.

Visible-Light Mediated Carbamoylation of Nitrones under a Continuous Flow Regime

Herein, we report a rapid and scalable continuous-flow photocatalytic approach for the carbamoylation of nitrones. This protocol makes use of readily available 4-amido-1,4 dihydropyridines as carbamoyl radical precursors. The scope of this transformation exhibits high compatibility with complex structures containing amino acids, peptides, and glycosides. Importantly, the developed method allows a photocatalytic synthetic strategy in combination with flow conditions, maximizing the potential and efficiency for the synthesis of valuable α-(N-hydroxy)amino amides.

UHPLC-MS Chemical Fingerprinting and Antioxidant, Enzyme Inhibition, Anti-Inflammatory In Silico and Cytoprotective Activities of Cladonia chlorophaea and C. gracilis (Cladoniaceae) from Antarctica

The lichen species Cladonia chlorophaea and C. gracilis (Cladoniaceae) are widely distributed in the island archipelago of maritime Antarctica and represent a natural resource of scientific interest. In this work, the metabolomic characterization of the ethanolic extracts of these species and the determination of the antioxidant activity, enzymatic inhibition and anti-inflammatory potential of selected compounds on the 5-lipoxygenase enzyme by molecular docking and cytoprotective activity in the SH-SY5Y cell line were carried out. Nineteen compounds were identified by liquid chromatography coupled with quadrupole-time-of-flight mass spectrometry (UHPLC-ESI-QTOF-MS) in each of the species. The contents of phenolic compounds, antioxidant activity, the inhibition of cholinesterases (acetylcholinesterase and butyrylcholinesterase) and digestive enzymes (α-glucosidase and pancreatic lipase) were variable among species, with better results in C. chlorophaea. Molecular docking evidenced significant binding affinities of some compounds for the 5-lipoxygenase enzyme, together with outstanding pharmacokinetic properties. Both extracts were shown to promote cell viability and a reduction in reactive oxygen species production in an H₂O₂-induced oxidative stress model. This study contributes to the chemical knowledge of the Cladonia species and demonstrates the biological potential for the prevention and promising treatment of central nervous system pathologies, inflammatory disorders and metabolic alterations.

Synthesis and structure-activity relationships for some novel diflapolin derivatives with benzimidazole subunit

A series of derivatives of the potent dual soluble epoxide hydrolase (sEH)/5-lipoxygenase-activating protein (FLAP) inhibitor diflapolin was designed, synthesised, and characterised. These novel compounds, which contain a benzimidazole subunit were evaluated for their inhibitory activity against sEH and FLAP. Molecular modelling tools were applied to analyse structure-activity relationships (SAR) on both targets and to predict solubility and gastrointestinal (GI) absorption. The most promising dual inhibitors of these series are 5a, 6b, and 6c.

Active Compounds in Zingiber officinale as Possible Redox Inhibitors of 5-Lipoxygenase Using an In Silico Approach

5-Lipoxygenase (5-LOX) converts arachidonic acid to lipidic inflammatory mediators such as leukotrienes (LTs). In diseases such as asthma, LTs contribute to a physiopathology that could be reverted by blocking 5-LOX. Natural products with anti-inflammatory potential such as ginger have been used as nutraceuticals since ancient times. 6-Gingerol and 6-shogaol are the most abundant compounds in the ginger rhizome; they possess anti-inflammatory, antioxidant, and chemopreventive properties. In the present study, 6-gingerol and 6-shogaol structures were analyzed and compared with two commercial 5-LOX inhibitors (zileuton and atreleuton) and with other inhibitor candidates (3f, NDGA, CP 209, caffeic acid, and caffeic acid phenethyl ester (CAPE)). The pharmacokinetics and toxicological properties of 6-gingerol, 6-shogaol, and the other compounds were evaluated. Targeted molecular coupling was performed to identify the optimal catalytic pocket for 5-LOX inhibition. The results showed that 6-gingerol and 6-shogaol follow all of the recommended pharmacokinetic parameters. These compounds could be inhibitors of 5-LOX because they present specific interactions with the residues involved in molecular inhibition. The current study demonstrated the potential of 6-gingerol and 6-shogaol as anti-inflammatory agents that inhibit 5-LOX, as they present a high level of performance in the toxicological analysis and could be catabolized by the cytochrome p450 enzymatic complex; however, 6-gingerol was superior in safety compared to 6-shogaol.

Thiophene-Based Compounds with Potential Anti-Inflammatory Activity

Rheumatoid arthritis, arthrosis and gout, among other chronic inflammatory diseases are public health problems and represent major therapeutic challenges. Non-steroidal anti-inflammatory drugs (NSAIDs) are the most prescribed clinical treatments, despite their severe side effects and their exclusive action in improving symptoms, without effectively promoting the cure. However, recent advances in the fields of pharmacology, medicinal chemistry, and chemoinformatics have provided valuable information and opportunities for development of new anti-inflammatory drug candidates. For drug design and discovery, thiophene derivatives are privileged structures. Thiophene-based compounds, like the commercial drugs Tinoridine and Tiaprofenic acid, are known for their anti-inflammatory properties. The present review provides an update on the role of thiophene-based derivatives in inflammation. Studies on mechanisms of action, interactions with receptors (especially against cyclooxygenase (COX) and lipoxygenase (LOX)), and structure-activity relationships are also presented and discussed. The results demonstrate the importance of thiophene-based compounds as privileged structures for the design and discovery of novel anti-inflammatory agents. The studies reveal important structural characteristics. The presence of carboxylic acids, esters, amines, and amides, as well as methyl and methoxy groups, has been frequently described, and highlights the importance of these groups for anti-inflammatory activity and biological target recognition, especially for inhibition of COX and LOX enzymes.

Functionalized Homologues and Positional Isomers of Rabbit 15-Lipoxygenase RS75091 Inhibitor

BACKGROUND

RS75091 is a cinnamic acid derivative that has been used for the crystallization of the rabbit ALOX15-inhibitor complex. The atomic coordinates of the resolved ALOX15-inhibitor complex were later used to define the binding sites of other mammalian lipoxygenase orthologs, for which no direct structural data with ligand has been reported so far.

INTRODUCTION

The putative binding pocket of the human ALOX5 was reconstructed on the basis of its structural alignment with rabbit ALOX15-RS75091 inhibitor. However, considering the possible conformational changes the enzyme may undergo in solution, it remains unclear whether the existing models adequately mirror the architecture of the ALOX5 active site.

METHODS

In this study, we prepared a series of RS75091 derivatives using a Sonogashira coupling reaction of regioisomeric bromocinnamates with protected acetylenic alcohols and tested their inhibitory properties on rabbit ALOX15.

RESULTS

A bulky pentafluorophenyl moiety linked to either ortho- or metha-ethynylcinnamates via aliphatic spacer does not significantly impair the inhibitory properties of RS75091.

CONCLUSION

Hydroxylated 2- and 3-alkynylcinnamates may be suitable candidates for incorporation of an aromatic linker group like tetrafluorophenylazides for photoaffinity labeling assays.