3-Arylcoumarins: Synthesis and potent anti-inflammatory activity

Chronic inflammation is the persistent and excessive immune response and can lead to a variety of diseases. Aiming to discover new compounds with anti-inflammatory activity, we report herein the synthesis and biological evaluation of 3-arylcoumarins. Thirty five 3-arylcoumarins were prepared through Perkin condensation and further acid-promoted hydrolysis if necessary. In lipopolysaccharide-activated mouse macrophage RAW264.7 cells, 6,8-dichloro-3-(2-methoxyphenyl)coumarin (16) and 6-bromo-8-methoxy-3-(3-methoxyphenyl)coumarin (25) exhibited nitric oxide production inhibitory activity with the IC₅₀ values of 8.5 μM and 6.9 μM, respectively, providing a pharmacological potential as anti-inflammatory agents.     

Isoflavanoids of dalbergia Oliveri

The heartwood of Dalbergia oliveri has yielded 11 natural products of which two are new 3-phenylcoumarins. The structures of the extractives have been examined by physical methods and in addition the assigned structures have been confirmed by synthesis. The oxygenation pattern relating the structures of chalcone, isoflavone, pterocarpans, 3-arylcoumarins, coumestones and the isoflavan and isoflavanone suggests a common biosynthetic origin.     

4-Arylcoumarins from Coutarea hexandra

Four new 4-arylcoumarins have been isolated from Coutarea hexandra and their structures established as 5,7,4′-trimethoxy-4-phenylcoumarin, 4′-hydroxy-5,7-dimethoxy-4-phenylcoumarin, 3′-hydroxy-5,7-4′-trimethoxy-4-phenylcoumarin and 3′,4′-dihydroxy-5,7-dimethoxy-4-phenylcoumarin.     

Synthesis and biological evaluation of 3-arylcoumarin derivatives as potential anti-diabetic agents

A variety of substituted 3-arylcoumarin derivatives were synthesised through microwave radiation heating. The method has characteristics of environmental friendliness, economy, simple separation, and purification process, less by-products and high reaction yield. Those 3-arylcoumarin derivatives were screened for antioxidant, α-glucosidase inhibitory and advanced glycation end-products (AGEs) formation inhibitory. Most compounds exhibited significant antioxidant and AGEs formation inhibitory activities. Anti-diabetic activity studies showed that compounds 11 and 17 were equipotent to the standard drug glibenclamide in vivo. According to the experimental results, the target compound 35 can be used as a lead compound for the development of new anti-diabetic drugs. The whole experiment showed that anti-diabetic activity is prevalent in 3-arylcoumarins, which added a new natural skeleton to the development of anti-diabetic active drugs.     

Synthesis of 4-arylcoumarins from Coutarea hexandra

The structures assigned to the 5,7-dimethoxy-4-arylcoumarins isolated from Coutarea hexandra have been confirmed by synthesis, via Pechmann condensation of phloroglucinol and an ethyl benzoylacetate derivative, the hydroxy groups of which were protected either by benzylation or by methylenedioxy group formation.     

A new synthesis of isoaurones: cytotoxic activity of compounds related to the alleged structure of isoaurostatin

A new synthesis of isoaurones related to the alleged structure of isoaurostatin, via Heck intramolecular cyclization of cinnamic esters of 2-iodophenols, is reported. The cytotoxic activity of these isoaurones is lower than that of the structurally very similar 4-arylcoumarins.     

Synthesis and biological evaluation of 4-arylcoumarins as potential anti-Alzheimer’s disease agents

Alzheimer's disease (AD) is a progressive neurological degenerative disease that has complex pathogenesis. A variety of studies in humans indicate that several enzymes inhibitors can be useful in the treatment of AD, including acetylcholinesterase (AchE), butyrylcholinesterase (BuChE) and monoamine oxidase (MAO). Various substituted 4-arylcoumarin derivatives were synthesised, and their activity in vitro were investigated, including AChE/BuChE inhibitory activity, MAO inhibitory activity, and antioxidant activity. Most of the compounds were found to exhibit high inhibitory activity, and individual compounds have extremely excellent activities. Therefore 4-arylcoumarins provides an idea for drugs design for the development of therapeutic or preventive agents for AD.     

Structural and functional relationships of natural and artificial dimeric bovine ribonucleases: New scaffolds for potential antitumor drugs

Protein aggregation via 3D domain swapping is a complex mechanism which can lead to the acquisition of new biological, benign or also malignant functions, such as amyloid deposits. In this context, RNase A represents a fascinating model system, since by dislocating different polypeptide chain regions, it forms many diverse oligomers. No other protein displays such a large number of different quaternary structures. Here we report a comparative structural analysis between natural and artificial RNase A dimers and bovine seminal ribonuclease, a natively dimeric RNase with antitumor activity, with the aim to design RNase A derivatives with improved pharmacological potential.     

A comprehensive review on synthesis and designing aspects of coumarin derivatives as monoamine oxidase inhibitors for depression and Alzheimer’s disease

Monoamine oxidase (MAO) enzyme inhibition is a crucial target for the management of depression and Alzheimer disease and inhibitors of MAO are the most important drugs for their management. Coumarins are a large family of compounds, of natural and synthetic origin, that exhibit a variety of pharmacological activities, including MAO inhibition. The current review highlights the design and synthetic methods of coumarin derivatives as well as coumarins obtained from plant source as MAO inhibitors for treatment of depression and Alzheimer disease with salient finding related to structure–activity relationship. The aim of present review is to find out natural as well as synthetic coumarins as MAO inhibitors.     

Phenolics with PPAR-gamma ligand-binding activity obtained from licorice (Glycyrrhiza uralensis roots) and ameliorative effects of glycyrin on genetically diabetic KK-A(y) mice

The EtOAc extract of licorice (Glycyrrhiza uralensis roots) exhibited considerable PPAR-gamma ligand-binding activity. Bioassay-guided fractionation of the extract using a GAL-4-PPAR-gamma chimera assay method resulted in the isolation of two isoflavenes, one of which is a new compound named dehydroglyasperin D, an isoflavan, two 3-arylcoumarins, and an isoflavanone as the PPAR-gamma ligand-binding active ingredients of licorice. The isoprenyl group at C-6 and the C-2' hydroxyl group in the aromatic ring-C part in the isoflavan, isoflavene, or arylcoumarin skeleton were found to be the structural requirements for PPAR-gamma ligand-binding activity. Glycyrin, one of the main PPAR-gamma ligands of licorice, significantly decreased the blood glucose levels of genetically diabetic KK-A(y) mice.     

天然药物紫杉醇的研究与开发综述

本文对近年来紫杉醇(Taxol)的研究与开发进行了综述,其中包括:1.对紫杉醇研究的历史回顾;2.独特的药理作用机制;3.在植物界的分布;4.前药设计;5.半合成;6.全合成;7.组织培养;8.真菌发酵;9.构效关系等。     

Circular dichroism, a powerful tool for the assessment of absolute configuration of flavonoids

Circular dichroism is a powerful tool for establishing the absolute configuration of flavonoids and proanthocyanidin analogues. It has been utilized to study the configuration of flavanones, dihydroflavonols (3-hydroxyflavanones), flavan-3-ols, flavan-4-ols, flavan-3,4-diols, flavans, isoflavans, isoflavanones, pterocarpans, 6a-hydroxypterocarpans, rotenoids, 12a-hydroxyrotenoids, neoflavonoids, 3,4-dihydro-4-arylcoumarins, 4-arylflavan-3-ols, auronols, homoisoflavanones, proanthocyanidins, and various classes of biflavonoids. Results relevant to the correlation of circular dichroic data and the absolute configuration of the diastereoisomers of some of the above classes of compounds will be discussed.     

A comparison between two brine shrimp assays to detect in vitro cytotoxicity in marine natural products

Background  

The brine shrimp lethality assay is considered a useful tool for preliminary assessment of toxicity. It has also been suggested for screening pharmacological activities in plant extracts. However, we think that it is necessary to evaluate the suitability of the brine shrimp methods before they are used as a general bio-assay to test natural marine products for pharmacological activity.     

Recent advances in the discovery and development of glyoxalase I inhibitors

Glyoxalase I (GLO1) is a homodimeric Zn²⁺-metalloenzyme that catalyses the transformation of methylglyoxal (MG) to d-lacate through the intermediate S-d-lactoylglutathione. Growing evidence indicates that GLO1 has been identified as a potential target for the treatment cancer and other diseases. Various inhibitors of GLO1 have been discovered or developed over the past several decades including natural or natural product-based inhibitors, GSH-based inhibitors, non-GSH-based inhibitors, etc. The aim of this review is to summarize recent achievements of concerning discovery, design strategies, as well as pharmacological aspects of GLO1 inhibitors with the target of promoting their development toward clinical application.     

Interaction of the putative anticancer alkaloid chelerythrine with nucleic acids: biophysical perspectives

Alkaloids represent an important group of molecules that have immense pharmacological potential. Benzophenanthridine alkaloids are one such class of alkaloids known for their myriad pharmacological activities that include potential anticancer activities. Chelerythrine is a premier member of the benzophenanthridine family of the isoquinoline group. This alkaloid is endowed with excellent medicinal properties and exhibits antibacterial, antimicrobial and anti-inflammatory properties. The molecular basis of its therapeutic activity is considered due to its nucleic acid binding capabilities. This review focuses on consolidating the current status on the nucleic acid binding properties of chelerythrine that is essential for the rational design and development of this alkaloid as a potential drug. This work reviews the interaction of chelerythrine with different natural and synthetic nucleic acids like double- and single-stranded DNAs, heat-denatured DNA, quadruplex DNA, double- and single-stranded RNA, tRNA and triplex and quadruplex RNA. The review emphasizes on the mode, specificity, conformational aspects and energetics of the binding that is particularly helpful for developing nucleic acid targeted therapeutics. The fundamental results discussed in this review will greatly benefit drug development for many diseases and serve as a database for the design of futuristic benzophenanthridine-based therapeutics.     

1,3-Dinitrates of cyclooxygenase metabolites of endocannabinoid 2-arachidonoylglycerol. Synthesis and properties

The 1,3-Dinitrates of glycerol esters of natural prostaglandins that are the cyclooxygenase metabolites of 2-arachidonoylglycerol, an endogenous ligand of cannabinoid receptors, were synthesized for the first time. Four methods of synthesis of these esters were developed via the activation of a carboxyl group and their chemical and pharmacological properties were investigated. The esters exhibit a more selective pharmacological spectrum of activities in comparison with the corresponding natural prostaglandins: some types of myotropic activity were enhanced, while others were loosened. 1,3-dinitroglycerol esters act as vasodilators, whereas the majority of natural prostaglandins act as vasoconstrictors. The observed changes result from the introduction of an NO-releasing fragment into prostaglandin molecule.     

Osthole interacts with an ER‐mitochondria axis and facilitates tumor suppression in ovarian cancer

Osthole is a natural coumarin found in a variety of plants and has been reported to have diverse biological functions, including antimicrobial, antiviral, immunomodulatory, and anticancer effects. Here, we investigated the natural derivative osthole as a promising anticancer compound against ovarian cancer and evaluated its ability to suppress and abrogate tumor progression. In addition, we found the endoplasmic reticulum‐mitochondrial axis‐mediated anticancer mechanisms of osthole against ES2 and OV90 ovarian cancer cells and demonstrated its calcium‐dependent pharmacological potential. Mechanistically, osthole was found to target the phosphatidylinositol 3‐kinase/mitogen‐activated protein kinase signaling pathway to facilitate tumor suppression in ovarian cancer. Furthermore, we identified the effects of osthole in a three‐dimensional tumor‐formation model using the zebrafish xenograft assay, providing convincing evidence of the pharmacological effects of osthole within the anchorage‐independent tumor microenvironment. These findings suggest that osthole has strong potential as a pharmacological agent for targeting ovarian cancer.     

Xanthones and Cancer: from Natural Sources to Mechanisms of Action

Xanthones are a class of heterocyclic natural products that have been widely studied for their pharmacological potential. In fact, they have been serving as scaffolds for the design of derivatives focusing on drug development. One of the main study targets of xanthones is their anticancer activity. Several compounds belonging to this class have already demonstrated cytotoxic and antitumor effects, making it a promising group for further exploration. This review therefore focuses on recently published studies, emphasizing their natural and synthetic sources and describing the main mechanisms of action responsible for the anticancer effect of promising xanthones.     

Nucleic acids binding strategies of small molecules: Lessons from alkaloids

Background

Nucleic acids are now important targets for therapeutic intervention. Alkaloids are an important class of molecules that have myriad therapeutic utility. Isoquinoline and benzophenanthridine alkaloids exhibit multiple pharmacological activities which are often related to their strong nucleic acid binding abilities. Therefore, a review of their interaction aspects with varying nucleic acid structures is essential for rational design and development as therapeutic agents.

Novel Phenolic Inhibitors of Small/Intermediate-Conductance Ca2+-Activated K+ Channels,KCa3.1 and KCa2.3

Background

KCa3.1 channels are calcium/calmodulin-regulated voltage-independent K⁺ channels that produce membrane hyperpolarization and shape Ca²⁺-signaling and thereby physiological functions in epithelia, blood vessels, and white and red blood cells. Up-regulation of KCa3.1 is evident in fibrotic and inflamed tissues and some tumors rendering the channel a potential drug target. In the present study, we searched for novel potent small molecule inhibitors of KCa3.1 by testing a series of 20 selected natural and synthetic (poly)phenols, synthetic benzoic acids, and non-steroidal anti-inflammatory drugs (NSAIDs), with known cytoprotective, anti-inflammatory, and/or cytostatic activities.

Methodology/Principal Findings

In electrophysiological experiments, we identified the natural phenols, caffeic acid (EC50 1.3 µM) and resveratrol (EC50 10 µM) as KCa3.1 inhibitors with moderate potency. The phenols, vanillic acid, gallic acid, and hydroxytyrosol had weak or no blocking effects. Out of the NSAIDs, flufenamic acid was moderately potent (EC50 1.6 µM), followed by mesalamine (EC50≥10 µM). The synthetic fluoro-trivanillic ester, 13b ([3,5-bis[(3-fluoro-4-hydroxy-benzoyl)oxymethyl]phenyl]methyl 3-fluoro-4-hydroxy-benzoate), was identified as a potent mixed KCa2/3 channel inhibitor with an EC50 of 19 nM for KCa3.1 and 360 pM for KCa2.3, which affected KCa1.1 and Kv channels only at micromolar concentrations. The KCa3.1/KCa2-activator SKA-31 antagonized the 13b-blockade. In proliferation assays, 13b was not cytotoxic and reduced proliferation of 3T3 fibroblasts as well as caffeic acid. In isometric vessel myography, 13b increased contractions of porcine coronary arteries to serotonin and antagonized endothelium-derived hyperpolarization-mediated vasorelaxation to pharmacological KCa3.1/KCa2.3 activation.

Conclusions/Significance

We identified the natural phenols, caffeic acid and resveratrol, the NSAID, flufenamic acid, and the polyphenol 13b as novel KCa3.1 inhibitors. The high potency of 13b with pan-activity on KCa3.1/KCa2 channels makes 13b a new pharmacological tool to manipulate inflammation and cancer growth through KCa3.1/KCa2 blockade and a promising template for new drug design.