Synthesis and contractile activity of substituted 1,2,3,4-tetrahydroisoquinolines

Synthesis, Molecular Docking, and Biological Evaluation of Novel Anthranilic Acid Hybrid and Its Diamides as Antispasmodics

The present article focuses on the synthesis and biological evaluation of a novel anthranilic acid hybrid and its diamides as antispasmodics. Methods: Due to the predicted in silico methods spasmolytic activity, we synthesized a hybrid molecule of anthranilic acid and 2-(3-chlorophenyl)ethylamine. The obtained hybrid was then applied in acylation with different acyl chlorides. Using in silico analysis, pharmacodynamic profiles of the compounds were predicted. A thorough biological evaluation of the compounds was conducted assessing their in vitro antimicrobial, cytotoxic, anti-inflammatory activity, and ex vivo spasmolytic activity. Density functional theory (DFT) calculation, including geometry optimization, molecular electrostatic potential (MEP) surface, and HOMO-LUMO analysis for the synthesized compounds was conducted using the B3LYP/6-311G(d,p) method to explore the electronic behavior, reactive regions, and stability and chemical reactivity of the compounds. Furthermore, molecular docking simulation along with viscosity measurement indicated that the newly synthesized compounds interact with DNA via groove binding mode. The obtained results from all the experiments demonstrate that the hybrid molecule and its diamides inherit spasmolytic, antimicrobial, and anti-inflammatory capabilities, making them excellent candidates for future medications.

Drug-Delivery Silver Nanoparticles: A New Perspective for Phenindione as an Anticoagulant

Anticoagulants prevent the blood from developing the coagulation process, which is the primary cause of death in thromboembolic illnesses. Phenindione (PID) is a well-known anticoagulant that is rarely employed because it totally prevents coagulation, which can be a life-threatening complication. The goal of the current study is to synthesize drug-loaded Ag NPs to slow down the coagulation process. Methods: A rapid synthesis and stabilization of silver nanoparticles as drug-delivery systems for phenindione (PID) were applied for the first time. Results: Several methods are used to determine the size of the resulting Ag NPs. Additionally, the drug-release capabilities of Ag NPs were established. Density functional theory (DFT) calculations were performed for the first time to indicate the nature of the interaction between PID and nanostructures. DFT findings supported that galactose-loaded nanostructure could be a proper delivery system for phenindione. The drug-loaded Ag NPs were characterized in vitro for their antimicrobial, cytotoxic, and anticoagulant activities, and ex vivo for spasmolytic activity. The obtained data confirmed the drug-release experiments. Drug-loaded Ag NPs showed that prothrombin time (PT, sec) and activated partial thromboplastin time (APTT, sec) are approximately 1.5 times longer than the normal values, while PID itself stopped coagulation at all. This can make the PID-loaded Ag NPs better therapeutic anticoagulants. PID was compared to PID-loaded Ag NPs in antimicrobial, spasmolytic activity, and cytotoxicity. All the experiments confirmed the drug-release results.

In Silico, In Vitro, and Ex Vivo Biological Activity of Some Novel Mebeverine Precursors

Irritable bowel syndrome (IBS) is a functional gastroenterological disorder with complex pathogenesis and multifaceted therapy approaches, aimed at alleviating clinical symptoms and improving the life quality of patients. Its treatment includes dietary changes and drugs from various pharmacological groups such as antidiarrheals, anticholinergics, serotonin receptor antagonists, targeting chloride ion channels, etc. The present article is focused on the synthesis and biological evaluation of some mebeverine precursors as potential antispasmodics.

METHODS

In silico analysis aimed at predicting the pharmacodynamic profile of the compounds was performed. Based on these predictions, ex vivo bioelectrical activity (BEA) and immunohistochemical effects of the compounds were established. A thorough biological evaluation of the compounds was conducted assessing their in vitro antimicrobial and cytotoxic activity.

RESULTS

All the newly synthesized compounds exerted drug-like properties, whereby 3-methyl-1-phenylbutan-2-amine 3 showed a significant change in BEA due to Ca²⁺ channel regulation, Ca²⁺ influx modulation, and a subsequent change in smooth muscle cell response. The immunohistochemical studies showed a good correlation with the obtained data on the BEA, defining amine 3 as a leader structure. No cytotoxicity to human malignant leukemic cell lines (LAMA-84, K-562) was observed for all tested compounds.

CONCLUSION

Based on the experimental results, we outlined 3-methyl-1-phenylbutan-2-amine 3 as a potential effective choice for orally active long-term therapy of IBS.

Synthesis of N-[1-(2-Acetyl-4,5-dimethoxyphenyl)propan-2-yl]benzamide and Its Copper(II) Complex

This paper represents a convenient method for the synthesis of N-[1-(2-acetyl-4,5-dimethoxyphenyl)propan-2-yl]benzamide and its Cu(II) complex. In silico analysis predicted spasmolytic activity for the compound. Based on the in silico calculations, the importance of the predicted ketoamide, and our previous experiments, we synthesized the ketoamide via ortho-acylation of N-[1-(3,4-dimethoxyphenyl)propan-2-yl]benzamide with acetic anhydride in polyphosphoric acid. We applied the title ketoamide in reaction with Cu(II) varying the solvents. We found that the reaction leads to the formation of a coordination compound when the ligand dissolved in DMSO reacts with a water solution of CuCl₂ in an alkaline environment in a molar ratio M : L : OH^- = 1 : 2 : 2. The structures of the new compounds are discussed based on their melting points, IR, ¹H, ¹³C NMR and Raman spectral data.

Ex Vivo and In Vivo Study of Some Isoquinoline Precursors

This article concerns the synthesis and biological activities of some N-(1-(3,4-dimethoxyphenyl)propan-2-yl) amides as isoquinoline precursors and compounds with smooth muscle (SM) relaxant activity. Aim: find the biological activity of N-(1-(3,4-dimethoxyphenyl)propan-2-yl) amides and compare it with papaverine, an isoquinoline alkaloid that has been known as a brain and coronary vasodilator and SM relaxant. Materials and methods: In silico simulation with the PASS online program predicts SM relaxant activity for the compounds. The amides were tested on the isolated gastric SM preparations (SMPs) from rats to determine their effects on spontaneous contractile activity (CA) compared with papaverine. The in vivo effect on the learning and memory processes of rats was also assessed. Results: the data from the isometric measurements showed that one of the compounds caused ex vivo relaxation in circular SM tissues isolated from the stomach (corpus) of male Wistar rats. Conclusion: We found that the compound’s SM relaxation uses the papaverine pathway. It also has an improving effect on the cognitive functions of learning and memory processes in rats.

Crystal Structure of N-(2-Benzoyl-4,5-dimethoxyphenethyl)-2-phenylacetamide

The crystal structure of N-(2-benzoyl-4,5-dimethoxyphenethyl)-2-phenylacetamide indicates that the compound crystallizes in the monoclinic C2/c space group with eight molecules in the unit cell. The heteroatoms from the amide group form a chain of intermolecular N-H ··· O hydrogen bonds propagating along the b axis. The carbonyl group from the benzoyl substituent participates in short contacts with two H-atoms from the ethyl or phenyl groups.

Ability of 2-Chloro-N-(1-(3,4-dimethoxyphenyl)propan-2-yl)-2-phenylacetamide to Stimulate Endogenous Nitric Oxide Synthesis

Papaverine is one of the isoquinoline alkaloids derived from opium which is a vasodilator and smooth muscle relaxant. Using its chemical structure as a basic model, we synthesized 2-chloro-N-(1-(3,4-dimethoxyphenyl)propan-2-yl)-2-phenylacetamide as an isoquinoline precursor (IQP). Aim: Clarifying the nature of the relationship between IQP as a new biologically active molecule and the neurotransmitters acetylcholine (ACh) and serotonin (5-hydroxytryptamine, 5-HT), as well as with the nitric oxide (NO). Materials and methods: The IQP compound was tested on the isolated gastric smooth muscle preparations (SMPs) from rats to determine its effects on spontaneous contractile activity. NO concentration in tissue homogenates was determined, and immunohistochemistry was used to visualize the expression of neuronal nitric oxide synthase (nNOS) and endothelial nitric oxide synthase (eNOS) in smooth muscle (SM) cells. Results: The data from the isometric measurements suggest that IQP has an additional specific action affecting the intracellular signaling pathways of 5-HT. Using immunohistochemistry, we found that the combination of 5-HT and IQP affected the density and intensity of nNOS-positive cells, which increase significantly in the myenteric plexus and SM cells. Conclusions: In conclusion, IQP is involved in the regulation of intestinal neurons expressing nNOS, affects the function of nNOS/NO, and, by this mechanism, probably regulates the spontaneous contractile activity of gastric SM.

Microbial transformation of some simple isoquinoline and benzylisoquinoline alkaloids and in vitro studies of their metabolites

Simple isoquinoline alkaloids (heliamine, dehydroheliamine), a phthalide isoquinoline alkaloid noscapine, and an aporphine alkaloid boldine are biosynthetically derived from an amino acid tyrosine. These substrates and a simple synthetic isoquinoline alkaloid (2-acetyl-7-amino-1,2,3,4-tetrahydroisoquinoline) contain an isoquinoline nucleus. The biotransformation of these substrates via reduction, oxidation, hydroxylation, and N-oxidation reactions with different microorganism produced nine metabolites, namely: N-(2-acetyl-1,2,3,4-tetrahydroisoquinolin-7-yl) acetamide (Metabolite 1), heliamine N-oxide (Metabolite 2), 6,7-dimethoxyisoquinoline (Metabolite 3), 3,4-dihydro-6,7-dimethoxy isoquinolin-1-one (Metabolite 4), heliamine (Metabolite 5), dehydroheliamine N-oxide (Metabolite 6), cotarnine (Metabolite 7), 5-hydroxy cotarnine (Metabolite 8), and boldine N-oxide (Metabolite 9). Primarily, the metabolites are structurally elucidated by one-dimensional (1D) and two-dimensional (2D) nuclear magnetic resonance (NMR) analyses, and high-resolution electrospray ionization mass spectrometry (HR-ESIMS). Furthermore, the substrates and their isolated metabolites are evaluated in vitro for their anti-inflammatory, antimicrobial, cytotoxicity, and anticancer activities. The in vitro studies reveal that some of the isolated compounds are potential as anti-inflammatory, antitumor, and antimicrobial leads.

Hydrolysis of dihydroisoquinoline derivatives activated by sulfonyl or acyl chloride

A new, efficient, and mild strategy for hydrolysis of 3,4-dihydroisoquinoline imines activated by sulfonyl chloride or acyl chloride has been developed, by which method ketosulfonamides and ketoamides have been synthesized. This process tolerates broad scope with respect to both the sulfonyl chloride and acyl chloride with moderate to excellent yields. This protocol features a broad substrate scope for various kinds of 3,4-dihydroisoquinoline and mild reaction conditions without using strong acidic or basic conditions. These features show that this user-friendly and simple system could be applied in the future to the synthesis of a broader range of amino benzophenones.

The formation of the salt and neutral molecule cocrystal from equimolar solution of heliamine and bicyclo[2.2.1]hept-5-ene-endo-2,3-dicarboxylic acid

The possible interaction of 6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline (heliamine) with bicyclo[2.2.1]hept-5-ene-endo-2,3-dicarboxylic acid anhydride has been studied. Instead of the reaction with heliamine, the acid anhydride was hydrolyzed into the appropriate dicarboxylic acid. An equimolar mixture of unreacted heliamine and in-situ-generated dicarboxylic acid crystallized in space group P2₁/c. The comprehensive study of the obtained crystals shows that the peculiarities of the crystallization process lead to the formation of the salt-cocrystal structure where the dianion interacts simultaneously with two cations forming a chain as the primary structural motif. The neutral molecules of dicarboxylic acid link the dianions of the neighbouring chains, forming a layer as the secondary structural motif. As a result, the stronger hydrogen bonds formed by the neutral molecules play a secondary role in the crystal structure formation.

Retigabine diminishes the effects of acetylcholine, adrenaline and adrenergic agonists on the spontaneous activity of guinea pig smooth muscle strips in vitro

PURPOSE

The aim of this study is to evaluate the effect of retigabine on the smooth muscle response to acetylcholine, adrenaline, α-and β-adrenoceptor agonists.

METHODS

We studied the change in the spontaneous smooth muscle contraction of guinea pig gastric corpus strips before and after 20-min treatment with 2μM retigabine. We also evaluated the effect of retigabine on the smooth muscle response to 10μM acetylcholine, 1 and 10μM adrenaline, 1μM methoxamine, 0.1μM p-iodoclonidine and 10μM isoproterenol.

RESULTS

We observed a significant reduction in the effects of all studied mediators and agonists when they were added to organ baths in the presence of retigabine. Retigabine diminished the effect of acetylcholine on the spontaneous smooth muscle activity. The effect was fully antagonized by XE-991 (Kv7 channel blocker), which supports our hypothesis about the role of KCNQ channels in the registered changes. The increase in the contraction force after adding of 1μM adrenaline, methoxamine, and 0.1μM p-iodoclonidine was also significantly smaller in presence of retigabine. However, comparing the effect of 10μM adrenaline on the contractility before and after treatment with retigabine, we observed increased contractility when retigabine was present in the organ baths.

CONCLUSION

A possible explanation for the observed diminished effects of mediators and receptor agonists is that the effect of retigabine on smooth muscle contractility is complex. The membrane hyperpolarization, the interaction between Kv7 channels and adrenoceptors, and the influence on signaling pathways may contribute to the summary smooth muscle response.

Activation of KCNQ channels located on the skeletal muscle membrane by retigabine and its influence on the maximal muscle force in rat muscle strips

Retigabine is a new antiepileptic drug with the main mechanism of action: activation of voltage-gated potassium channels (Kv7) represented in many tissues including the excitable cells-neuronal and muscular. The aim of this article is to determine the role of potassium channels located on the skeletal muscle membrane in the in vivo and in vitro reduction of muscle contractile activity induced by retigabine. We studied the effects of retigabine on the motor function in vivo using a bar holding test and exploratory activity using open field test in rats. Electrical field stimulation (EFS) was applied to skeletal muscle strips in vitro in order to evaluate muscular activity. We registered a significant decrease in the muscle tone and exploratory activity of rats, treated orally with 60 mg/kg bw retigabine. In vitro experiments showed decrease in the maximal muscle force of strips in the presence of retigabine in the medium after both indirect (nerve-like) and direct (muscle-like) stimulation. The effects were fully antagonized by XE-991 (Kv7 channel blocker), which supports our hypothesis about the relation between these types of potassium channels and the observed change in the muscle force. Based on these results, we can conclude that skeletal muscle Kv7 channels play a significant role in the myorelaxation and reduced muscle force registered after treatment with Kv7 channels openers (e.g., retigabine). The hyperpolarization of skeletal muscle membrane caused by accelerated K(+) efflux may be the underlying cause for the effect of retigabine on the muscle tone.

The kinetics and mechanism of the organo-iridium-catalysed enantioselective reduction of imines

The enantiomeric excess (ee) for the organo-iridium catalysed reduction of imines decreases during the reaction because the rate of formation of the (R)-product amine follows first-order kinetics whereas that for the (S)-enantiomer is zero-order.

Synthesis of C3/C1-Substituted Tetrahydroisoquinolines

A broad biological screening of the natural alkaloid N-methylisosalsoline (2) extracted from Hammadascoparia leaves against a panel of human and parasitic proteases revealed an interesting activity profile of 2 towards human 20S proteasome. This outcome suggests that the 1,2,3,4-tetrahydroisoquinoline skeleton may be exploited as a template for the development of novel anticancer agents. In this article, we report the synthesis and chemical characterization of a new series of isosalsoline-type alkaloids (10–11) with variations at N2 and C3 positions with respect to the natural Compound 2, obtained by a synthetic strategy that involves the Bischler-Napieralski cyclization. The substrate for the condensation to the tetrahydroisoquinoline system, i.e., a functionalized β-arylethyl amine, was obtained through an original double reduction of nitroalkene. The synthetic strategy can be directed to the construction of highly substituted and functionalized 1,2,3,4-tetrahydroisoquinolines.

Experimental and theoretical perspectives of the Noyori-Ikariya asymmetric transfer hydrogenation of imines

The asymmetric transfer hydrogenation (ATH) of imines catalyzed by the Noyori-Ikariya [RuCl(η6-arene)(N-arylsulfonyl-DPEN)] (DPEN=1,2-diphenylethylene-1,2-diamine) half-sandwich complexes is a research topic that is still being intensively developed. This article focuses on selected aspects of this catalytic system. First, a great deal of attention is devoted to the N-arylsulfonyl moiety of the catalysts in terms of its interaction with protonated imines (substrates) and amines (components of the hydrogen-donor mixture). The second part is oriented toward the role of the η6-coordinated arene. The final part concerns the imine substrate structural modifications and their importance in connection with ATH. Throughout the text, the summary of known findings is complemented with newly-presented ones, which have been approached both experimentally and computationally.