Molecular design and synthesis of 1,4-disubstituted piperazines as α(1)-adrenergic receptor blockers

New morpholine-containing pyrimidinones act on α-adrenoceptors

Drugs that act on α-adrenoceptors may contain morpholine and pyrimidinone heterocycles. The aim of this study was to synthesize a series of pyrimidinones (S6a-e and S8) and characterize their α-adrenoceptor activity. Cytotoxicity assays (MTT and LDH) were performed in A7r5 and HUVECs. Concentration-effect curves to phenylephrine (Phe) were performed in rat aortic rings in the presence of compounds S6a-e and S8 or vehicle. Nitric oxide (NO) production and NO stable metabolic products, nitrite and nitrate, expressed as total nitrogen oxides (NOx) were assessed in HUVECs by confocal microscopy with the DAF-2DA probe and by the Griess reaction, respectively. Molecular docking simulations were performed using the 6a compound and α2A-adrenoceptor. In the evaluated conditions, the percentage of viable cells and the release of LDH were similar between control cells and cells exposed to the tested pyrimidinones. S6d, S6e, S8, and the positive control prazosin (but not S6a, S6b, and S6c) decreased Phe-induced contractions in endothelium-denuded aortic rings. S6a, S6b, and S6c decreased Phe-induced contractions in endothelium-intact aortic rings. The effect of S6a was abolished by L-NAME. NO production and NOx levels were inhibited in the presence of the α2 receptor antagonist yohimbine and the NOS inhibitor L-NAME. The 6a docking simulation estimated that the mean binding free energy of the compound was lower than the estimated value for yohimbine. These data suggest that S6d, S6e, and S8 may be α1-adrenoceptor antagonists while S6a acts as an agonist of α2-adrenoceptors.

In Vitro Anticancer Activity Screening of Novel Fused Thiophene Derivatives as VEGFR-2/AKT Dual Inhibitors and Apoptosis Inducers

Protein kinases are seen as promising targets in controlling cell proliferation and survival in treating cancer where fused thiophene synthon was utilized in many kinase inhibitors approved by the FDA. Accordingly, this work focused on adopting fused thienopyrrole and pyrrolothienopyrimidine scaffolds in preparing new inhibitors, which were evaluated as antiproliferative agents in the HepG2 and PC-3 cell lines. The compounds 3b (IC₅₀ = 3.105 and 2.15 μM) and 4c (IC₅₀ = 3.023 and 3.12 μM) were the most promising candidates on both cells with good selective toxicity-sparing normal cells. A further mechanistic evaluation revealed promising kinase inhibitory activity, where 4c inhibited VEGFR-2 and AKT at IC₅₀ = 0.075 and 4.60 μM, respectively, while 3b showed IC₅₀ = 0.126 and 6.96 μM, respectively. Moreover, they resulted in S phase cell cycle arrest with subsequent caspase-3-induced apoptosis. Lastly, docking studies evaluated the binding patterns of these active derivatives and demonstrated a similar fitting pattern to the reference ligands inside the active sites of both VEGFR-2 and AKT (allosteric pocket) crystal structures. To conclude, these thiophene derivatives represent promising antiproliferative leads inhibiting both VEGFR-2 and AKT and inducing apoptosis in liver cell carcinoma.

Synthesis, 3D-pharmacophore modelling and 2D-QSAR study of new pyridine-3-carbonitriles as vasorelaxant active agents

A new set of pyridine-3-carbonitriles (3a–v) conjugated with various five-membered ring systems at pyridinyl C-6 were designed and synthesized as vasorelaxant active agents.

Synthesis and Antibacterial Activities of Different Five-Membered Heterocyclic Rings Incorporated with Pyridothienopyrimidine

Certain pyridothienopyrimidine derivatives exhibit antiatheroscleorotic, antibacterial, antiviral, antidepressant, antidiabetic, antihypertensive, anticancer, antihistaminic, antiallergic, anti-inflammatory, spasmolytic, analgesic, and neurotropic activities. 4-Hydrazino-7,9-dimethylpyrido[3',2':4,5]thieno[3,2-d]pyrimidine (1) is a reported pyridothienopyrimidine derivative. In the current study, (1) has been reacted with different reagents to obtain 12 new pyridothienopyrimidine derivatives. The newly synthesized five-membered heterocyclic rings incorporated with pyridothienopyrimidines have been screened for their antibacterial activities. The results encourage further studies on other possible biological activities.

Exploring the Chemistry and Therapeutic Potential of Triazoles: A Comprehensive Literature Review

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Triazole is a valuable platform in medicinal chemistry, possessing assorted pharmacological properties, which could play a major role in the common mechanisms associated with various disorders like cancer, infections, inflammation, convulsions, oxidative stress and neurodegeneration. Structural modification of this scaffold could be helpful in the generation of new therapeutically useful agents. Although research endeavors are moving towards the growth of synthetic analogs of triazole, there is still a lot of scope to achieve drug discovery break-through in this area. Upcoming therapeutic prospective of this moiety has captured the attention of medicinal chemists to synthesize novel triazole derivatives. The authors amalgamated the chemistry, synthetic strategies and detailed pharmacological activities of the triazole nucleus in the present review. Information regarding the marketed triazole derivatives has also been incorporated. The objective of the review is to provide insights to designing and synthesizing novel triazole derivatives with advanced and unexplored pharmacological implications.

NMR-based investigations of acyl-functionalized piperazines concerning their conformational behavior in solution

Selected N-benzoylated piperazine compounds were synthesized to study their conformational behavior using temperature-dependent 1H NMR spectroscopy. All investigated piperazines occur as conformers at room temperature resulting from the restricted rotation of the partial amide double bond. In the case of selected mono-N-benzoylated and unsymmetrically N,N'-substituted derivatives, the appearance of the 1H NMR spectrum was further shaped by the limited interconversion of the piperazine chair conformations. Therefore, two different coalescence points T C were determined and their resulting activation energy barriers ΔG ‡ were calculated to be between 56 and 80 kJ mol-1. In most of the cases, T C and ΔG ‡ for the amide site appeared to be higher than the corresponding values for the ring inversion. The influences of substituents on rotational and inversion barriers were analyzed by correlation to Hammett constants. The obtained results are discussed and interpreted in the context of literature data. An additional aryl substituent connected at the amine site led to reduced rotational and inversion barriers compared to the free secondary amine. To support and evidence the findings from the NMR analyses, single crystals of selected piperazines were obtained and XRD analyses were performed. To underline the results, two potential TGase 2 inhibitors were investigated showing energy barriers with similar values.

Eight new triterpenoids with inhibitory activity against HMG-CoA reductase from the medical mushroom Ganoderma leucocontextum collected in Tibetan plateau

Eight new triterpenoids, ganoleucoins T-Z(1-3, 5-8), and AA (9), together with eleven known triterpenes were isolated and identified from the wild fruiting bodies of the medicinal mushroom Ganoderma leucocontextum. The structures of new compounds were determined on the basis of NMR and MS spectral analysis. The inhibitory effects of 1-9 on HMG-CoA reductase were tested in vitro. Compounds 1, 7 and 8 showed significant HMG-CoA reductase inhibition with IC₅₀ values of 10.2, 9.72 and 8.68 μM, respectively. The other isolated compounds presented relatively weak inhibitory activity with IC₅₀ values >100 μM. Preliminary structure-activity relationship analysis showed that the HMG moiety in 7 and 8 contributed greatly to their inhibitory activity against HMG-CoA reductase. This work further demonstrates the mushroom G. leucocontextum to be valuable herbal medicine that deserves deep investigation.

Synthesis and activity of newly designed aroxyalkyl or aroxyethoxyethyl derivatives of piperazine on the cardiovascular and the central nervous systems

In the search for new hypotensive agents some new aroxyalkyl or aroxyethoxyethyl derivatives of piperazine have been synthesized and evaluated for their pharmacological properties. Pharmacological tests included receptor binding assays toward adrenergic receptors α₁, α₂ and β₁, additionally 5-HT_1A, functional bioassay and in vivo evaluation of hypotensive activity as well as antidepressant-like potential. All the tested compounds exhibited α₁-antagonistic properties, three of them possessed also hypotensive activity in rats. The most promising compound 3 1-[4-(2,6-dimethylphenoxy)butyl]-4-(2-methoxyphenyl)piperazine hydrochloride was a selective α₁ receptor antagonist (K_i=23.5±1.3, α₁/α₂=15.77, pK_B=8.538±0.109). It was active in all tested doses in vivo (1, 0.5, and 0.1mg/kg) and it reduced blood pressure by 10-13% at the dose of 1mg/kg (rats, i.v.). Compound 5 1-[2-(2,3-dimethylphenoxy)ethoxyethyl]-4-(2-methoxyphenyl)piperazine dihydrochloride exhibited the lowest dose for antidepressant-like activity 5mg/kgb.w. (mice, i.p.) without influence on spontaneous activity (mice, i.p.).

Piperazine scaffold: A remarkable tool in generation of diverse pharmacological agents

Piperazine is one of the most sought heterocyclics for the development of new drug candidates. This ring can be traced in a number of well established, commercially available drugs. Wide array of pharmacological activities exhibited by piperazine derivatives have made them indispensable anchors for the development of novel therapeutic agents. The review herein highlights the therapeutic significance of piperazine derivatives. Various therapeutically active piperazine derivatives developed by several chemists are reported here.