Synthesis of 6- and 9-alkylaminomethyl furoflavones as gastroprotective agents

Exploring the Immunomodulatory Properties of Red Onion (Allium cepa L.) Skin: Isolation, Structural Elucidation, and Bioactivity Study of Novel Onion Chalcones Targeting the A2A Adenosine Receptor

Onions are versatile and nutritious food widely used in various cuisines around the world. In our ongoing pursuit of bioactive substances with health benefits from red onion (Allium cepa L.) skin, a comprehensive chemical investigation was undertaken. Consequently, a total of 44 compounds, including three previously unidentified chalcones (1-3) were extracted from red onion skin. Of these isolates, chalcones 1-4 showed high affinity to A2A adenosine receptor (A2AAR), and chalcone 2 displayed the best binding affinity to A2AAR, with the IC50 value of 33.5 nM, good A2AAR selectivity against A1AR, A2BAR, and A3AR, and high potency in the cAMP functional assay (IC50 of 913.9 nM). Importantly, the IL-2 bioassay and the cell-mediated cytotoxicity assay demonstrated that chalcone 2 could boost T-cell activation. Furthermore, the binding mechanism of chalcone 2 with hA2AAR was elucidated by molecular docking. This work highlighted that the active chalcones in red onion might have the potential to be developed as A2AAR antagonists used in cancer immunotherapy.

Therapeutic Potential of Genus Pongamia and Derris: Phytochemical and Bioactivity

Genus Pongamia and Derris belong to the Leguminosae family and are reported synonymously in literature. Although many compounds have been isolated from different plant parts but seed oil is known to produce non-edible medicinally important furanoflavonoids. The seed oil, commonly known as Karanj oil in Ayurvedic and Siddha traditional systems of medicine, is reported for the treatment of various skin infections and psoriasis. Several phytopharmacological investigations have proved the medicinal potential of furanoflavonoids in the skin and other disorders. Not only furanoflavonoids but several other important phenolic constituents such as chalcones, dibenzoylmethanes, aurones, isoflavones, flavanone dihydroflavonol, flavans, pterocarpans, rotenoids, coumarins, coumestans, stilbenoids and peltygynoids and their glycosides have been reported for different biological activities including antihyperglycemic, anti-inflammatory, anticancer, insecticidal, anti-alzheimer's, gastro protective, antifungal, antibacterial, etc. In the present review, the phytochemistry and pharmacological activities of the genera Pongamia and Derris have been summarized.

Non-ulcerogenic pyrazolyl 2-hydroxychalcones and pyrazolylpyrazolines derived from naturally existing furochromone (khellin): semi-synthesis, docking study and anti-inflammatory activity

Novel pyrazolyl 2-hydroxychalcone derivatives 3a-e and pyrazolylpyrazoline derivatives 4a-e and 5a-j derived from the naturally existing furochromone (Khellin) were synthesized and evaluated for their in vivo anti-inflammatory activity. Most of the synthesized compounds showed better or comparable activity to that of Diclofenac as reference drug. Twelve compounds were evaluated for their ulcerogenic potential and exhibited no ulcerogenic effect. In addition compounds 3c, 5c and 5h as examples showed PGE₂ inhibition % 88.86, 65.87 and 44.06, respectively and TNFα inhibition % 48.62, 31.11 and 16.02, respectively in rat serum samples. Compounds 3c, 5c, 5h and Celecoxib were subjected to in vitro COX-1 and COX-2 inhibition assay, showed selectivity index 45.04, 102.04, 131.58 and 185.18, respectively. The computational finding supported those of in vitro, where the pyrazolylpyrazolines interacted with the COX-2 enzyme in a similar orientation to that of Celecoxib, while chlacones were found to exhibit similar orientation to that of Diclofenac.

Synthesis of Hydroxybenzofuranyl-pyrazolyl and Hydroxyphenyl-pyrazolyl Chalcones and Their Corresponding Pyrazoline Derivatives as COX Inhibitors, Anti-inflammatory and Gastroprotective Agents

Five new series of hydroxybenzofuranyl-pyrazolyl chalcones 3a,b, hydroxyphenyl-pyrazolyl chalcones 6a-c and their corresponding pyrazolylpyrazolines 4a, d, 7a-c and 8a-f have been synthesized and evaluated for their in vitro cyclooxygenase (COX)-1 and COX-2 inhibitory activity. All the synthesized compounds exhibited dual COX-1 and COX-2 inhibitory activity with obvious selectivity against COX-2. The pyrazolylpyrazolines 4a-d and 8a-f bearing two vicinal aryl moieties in the pyrazoline nucleus showed more selectivity towards COX-2. Within these two series, derivatives 4c, d and 8d-f bearing the benzenesulfonamide group were the most selective. Compounds 4a-d and 8a-f were further subjected to in vivo anti-inflammatory screening, ulcerogenic liability and showed good anti-inflammatory activity with no ulcerogenic effect. In addition compounds 4c and 8d as examples showed prostaglandin (PG)E2 inhibition % 44.23 and 51.4 respectively, tumor necrosis factor α (TNFα) inhibition % 33.48 and 41.41 respectively and gastroprotective effect in ethanol induced rodent gastric ulcer model. In addition, to explore the binding mode and selectivity of our compounds, 8d and celecoxib were docked into the active site of COX-1 and COX-2. It was found that compound 8d exhibited a binding pattern and interactions similar to that of celecoxib with COX-2 active site, while bitter manner of interaction than celecoxib to COX-1 active site.

NIPAAm-MMA nanoparticle-encapsulated visnagin ameliorates myocardial ischemia/reperfusion injury through the promotion of autophagy and the inhibition of apoptosis

The main method for the treatment of acute myocardial infarction (AMI) is percutaneous coronary intervention; however percutaneous coronary intervention will induce ischemia/reperfusion (IR) injury, resulting in the loss of cardiac function and cardiomyocyte death. An effective drug to target this condition is necessary. N-isopropylacrylamide and methacrylic acid were used to synthesize drug delivery nanoparticles (NP) containing the natural compound visnagin for IR injury treatment. It was demonstrated that NP containing fluorescein isothiocyanate localized to the site of myocardial IR, and that NP-visnagin treatment induced cardioprotection, reducing the size of the MI and ameliorating cardiac dysfunction through the induction of autophagy and the inhibition of apoptosis. In the future, visnagin may be suitable as a drug for IR injury treatment, and NP may be an effective drug delivery system.

Synthesis and tautomerization of hydroxylated isoflavones bearing heterocyclic hemi-aminals

The aminomethylation of hydroxylated isoflavones with 2-aminoethanol, 3-amino-1-propanol, 4-amino-1-butanol, and 5-amino-1-pentanol in the presence of excess formaldehyde led principally to 9-(2-hydroalkyl)-9,10-dihydro-4H,8H-chromeno[8,7-e][1,3]-oxazin-4-ones 4 and/or the tautomeric 7-hydroxy-8-(1,3-oxazepan-3-ylmethyl)-4H-chromen-4-ones 5. The ratio of these tautomers was dependent on solvent polarity, electronic effects of aryl substituents in the isoflavone and the structure of the amino alcohol. NMR studies confirmed the interconversion of tautomeric forms.

Mannich bases in medicinal chemistry and drug design

The biological activity of Mannich bases, a structurally heterogeneous class of chemical compounds that are generated from various substrates through the introduction of an aminomethyl function by means of the Mannich reaction, is surveyed, with emphasis on the relationship between structure and biological activity. The review covers extensively the literature reports that have disclosed Mannich bases as anticancer and cytotoxic agents, or compounds with potential antibacterial and antifungal activity in the last decade. The most relevant studies on the activity of Mannich bases as antimycobacterial agents, antimalarials, or antiviral candidates have been included as well. The review contains also a thorough coverage of anticonvulsant, anti-inflammatory, analgesic and antioxidant activities of Mannich bases. In addition, several minor biological activities of Mannich bases, such as their ability to regulate blood pressure or inhibit platelet aggregation, their antiparasitic and anti-ulcer effects, as well as their use as agents for the treatment of mental disorders have been presented. The review gives in the end a brief overview of the potential of Mannich bases as inhibitors of various enzymes or ligands for several receptors.

Advances in chemistry of chromone aminomethyl derivatives

Chromones play an important role in the design and discovery of new pharmacologically active compounds. A large volume of reports dedicated to synthesis and study of properties of nitrogen-containing chromone derivatives show important role of chromone alkaloid-like compounds. The present review covers achievements in the field of synthesis of chromone aminomethyl derivatives as one of perspective scaffolds.

Design, synthesis and structure-activity relationship of novel semi-synthetic flavonoids as antiproliferative agents

Various flavonoid scaffold based derivatives viz furochalcones (3a-e, 6a-d and 9a-d), furoflavones (10a-d, 11a-d, 12a-d, 18a&b), flavones (21a-d), furoaurones (13a,b, 14a-d and 15a-d) and 7-styrylfurochromones (22a-d and 25a-e) were designed and synthesized. The novel compounds were evaluated for their antiproliferative activity against a panel of 60 cancer cell lines comprising 9 types of tumors. Ten compounds belonging to the major subgroups of flavonoids viz furochalcones (3a, 3d, 6b, 9a and 9b), furoflavones (12a and 12c), furoaurones (15d), styrylfurochromones (25b and 25e) showed very promising activity. These active compounds were also evaluated in vitro as kinase inhibitors against CDK2/cyclin E1, CDK4/cyclin D1 and GSK-3β and the best inhibition was displayed against GSK-3β with the allylfurochalcone derivative 9b exhibiting 80% decrease in GSK-3β catalytic activity. On the other hand, the styrylfurochromone 25e interestingly showed a 13% enhancement of GSK-3β catalytic power and a 12% reduction in CDK4/cyclin D1 activity. Finally, the in vivo anti-tumor activity of 25e was evaluated against breast cancer induced in mice. The results showed a profound anti-tumor effect of 25e that accompanies a significant increase and decrease in the levels of GSK-3β and cyclin D1, respectively.

Celecoxib analogs bearing benzofuran moiety as cyclooxygenase-2 inhibitors: design, synthesis and evaluation as potential anti-inflammatory agents

Novel series of celecoxib analogs endowed with benzofuran moiety 3a-e and 9a-d were synthesized and evaluated for COX-1/COX-2 inhibitory activity in vitro. The most potent and selective COX-2 inhibitors - compounds 3c, 3d, 3e, 9c and 9d - were assessed for their anti-inflammatory activity and ulcerogenic liability in vivo. The 3-(pyridin-3-yl)pyrazole derivatives 3c and 3e exhibited the highest anti-inflammatory activity, that is equipotent to celecoxib. Furthermore, the tested compounds proved to have better gastric safety profile compared to celecoxib. In particular, compound 3e demonstrated about 40% reduction in ulcerogenic potential relative to the reference drug. Finally, molecular docking simulation of the new compounds in COX-2 active site and drug likeness studies showed good agreement with the obtained pharmaco-biological results.

DNA binding, antiviral activities and cytotoxicity of new furochromone and benzofuran derivatives

Bromination of visnagin (1) afforded 9-bromovisnagin (2) which on its alkaline hydrolysis afforded the 3-acetyl benzofuran derivative (3). The condensation of (3) with hydrazine hydrate, phenylhydrazine and/or hydroxylamine hydrochloride afforded the corresponding pyrazole derivatives (4a, b) and isoxazole derivative (4c). On the other hand, when compound 3 was condensed with some aromatic aldehydes, this yielded corresponding α, β-unsaturated keto derivatives (5a-e). Furthermore, when 1 was subjected to chlorosulfonation, the visnaginsulfonylchloride derivative 6 was afforded, which on amidation using morpholine, a sulonamido derivative (7) was obtained. Alkaline hydrolysis of the latter compound yielded 7-N-morpholinosulsamidobenzofuran (8) which was condensed with some aromatic aldehydes to yield the corresponding chalcone compounds (9a-e). Demethylation of visnagin afforded norvisnagin (10). The reaction of 10 with ethylbromoacetate in dry acetone yielded the ester benzopyran derivative (11) which reacted with hydrazine hydrate to afford the corresponding hydrazide derivative (12) and this was condensed with 3,4,5-trimethoxybenzaldehyde to give the corresponding hydrazone (13). A thaizolidinone derivative (14) was obtained by condensation of (13) with thioglycolic acid. Chloromethylation of norvisnagin afforded a 4-chloromethyl derivative (15) which reacted with different primary and secondary amines to yield the corresponding ethylamino derivative (16a, b). Moreover, mannich bases (16a, b) and (17a-c) were obtained by reacting norvisnagin with different primary and secondary amines in the presence of formalin but benzoylation of (16a, b) and (17a-c) afforded 4-oxybenzoyl derivative (18a-e). The prepared compounds were tested for their interaction with DNA; bromovisnagin 2 showed the highest affinity and compounds 6, 15, 8a, > 14, > 16b, 17a, and 16a showed moderate activity in decreasing potency. Moreover, compound 2 also was the most active as antiviral agent toward HS-I virus and compounds 6, 7, 15, 14, 16a, and 18a were found to be moderately active. CD(50) of the active compounds were also measured.

Selection, Preparation, and Evaluation of Small- Molecule Inhibitors of Toll-Like Receptor 4

Toll-like receptor 4 (TLR4), a membrane spanning receptor protein that functions in complex with its accessory protein MD-2, is an intriguing target for therapeutic development. Herein we report the identification of a series of novel TLR4 inhibitors and the development of a robust, enantioselective synthesis using an unprecedented Mannich-type reaction to functionalize a pyrazole ring. In silico and cellular assay results demonstrated that compound 1 and its analogues selectively block TLR4 activation in live cells. Animal model tests showed that 1 and its derivatives could potentiate morphine-induced analgesia in vivo, presumably by attenuating the opioid-induced TLR4 activation.

Natural Products as Gastroprotective and Antiulcer Agents: Recent Developments

Peptic ulcer, one of the most common gastrointestinal diseases, is a chronic inflammatory disease characterized by ulceration in the regions of the upper gastrointestinal tract where parietal cells are found and where they secrete hydrochloric acid and pepsin. The anatomical sites where ulcer occurs commonly are stomach and duodenum, causing gastric and duodenal ulcer, respectively. Physiopathology of ulcer is due to an imbalance between aggressive factors, such as acid, pepsin, Helicobacter pylori and non-steroidal anti-inflammatory agents, and local mucosal defensive factors, such as mucus bicarbonate, blood flow and prostaglandins. Several drugs are widely used to prevent or treat gastro-duodenal ulcers. These include H2-receptor antagonists, proton pump inhibitors and cytoprotectives. Due to problems associated with recurrence after treatment, there is therefore the need to seek alternative drug sources against ulcers. In recent years, a widespread search has been launched to identify new gastroprotective drugs from natural sources. The aim of the present review is to highlight the recent advances in current knowledge on natural products as gastroprotective and antiulcer agents and consider the future perspectives for the use of these compounds.