Synthesis, biological evaluation and structure–activity relationships of new phthalazinedione derivatives with vasorelaxant activity

Design, synthesis, and biological evaluation of novel NO-releasing 4-chromanone derivatives as potential vasodilator agents

The nitric oxide/cyclic guanosine monophosphate (NO/cGMP) signaling pathway is an effective mechanism involved in the treatment of hypertension. In our search for potential antihypertensive agents, a series of novel NO-donor derivatives of the 4-chromanone skeleton were designed and synthesized by coupling furoxans or nitrooxy NO-donor moieties. All derivatives showed enhanced nitric oxide releasing capacity and vasodilator activity with EC₅₀ values ranging from 0.0215 μM to 1.46 μM, obviously superior to those of precursor 3. These biological evaluations indicated that all compounds displayed an important vasorelaxant effect, and several compounds (9c, 14b, 14c, 14d) presented good vasodilator activity, with 14c being the best. Furthermore, molecular modeling studies revealed that compound 14c occupied the pocket well with the phosphodiesterase 5 domain in a favorable conformation. In conclusion, we observed that these novel compounds can act as structural templates for the design and subsequent development of new vasodilators and antihypertensive drugs.

Synthesis of Ziziphus spina-christi (Jujube) Root Methanol Extract Loaded Functionalized Silver Nanoparticle (ZS-Ag-NPs); Physiochemical Characterization and Effect of ZS-Ag-NPs on Adipocyte Maturation, Adipokine and Vascular Smooth Muscle Cell Interaction

In this research, a simple, green approach was employed to synthesize silver nanoparticles with the aid of Ziziphus spina-christi (L.) methanol root extract, which can act as a reducing, capping agent to treat obesity and inflammation. Globally, Ziziphus spina-christi (Jujube) root is used in traditional therapy as a lipolysis promoter. GC-MS results confirmed the availability of kaempferol (flavonol), cannabinol and indole-3-carboxylic acid in Ziziphus spina-christi root methanol extract (ZSE). ZSE silver nanoparticles (ZS-Ag-NPs) were synthesized and their effect on mitochondrial fatty acid oxidation capacity and adipokine levels in maturing adipocytes were analyzed. Maturing adipocytes treated with 0.4 µg/dL of ZSE and ZS-Ag-NPs significantly reduced the lipid content in adipocytes by 64% and 82%, respectively. In addition, lipolysis-related genes such as LPL (1.9 fold), HSL (2.3 fold), PGC-1α (3 fold), UCP-1 (4.1 fold), PRDM16 (2 fold) and PPARα (2.7 fold) increased significantly in ZS-Ag-NPs treated maturing adipocytes. The ZS-Ag-NPs treatment significantly decreased insulin resistance and metabolic inflammation-related LTB4-R, TNF-α, IL-4 and STAT-6 mRNA levels. Mitochondrial thermogenesis stimulating capacity of ZS-Ag-NPs was further confirmed by the significantly enhanced CREB-1 and AMPK protein levels in adipocytes. Furthermore, ZS-Ag-NPs treated adipokines (condition media, CM) were treated with human umbilical vein endothelial cells (HUVECs) to determine cytotoxicity and pro-inflammatory stimulus capacity. We found that ZS-Ag-NPs treated adipocyte CM effectively increased mRNA expression levels of the vascular endothelial cell growth factor (VEGF), and down-regulated oxidative stress (LPO, eNOS, and HO) and vascular cell inflammation (ICAM, VCAM, TNF-α, IL-1β, and NF-κB). In conclusion, ZS-Ag-NPs displayed an action at the molecular level in mitochondrial fatty acid oxidation, decreased adipokine secretion in adipocytes, and enhanced vascular endothelial cell growth. This molecular mechanical action of ZS-Ag-NPs reduced effectively obesity progressions and metabolic inflammatory pathogenesis associated with aging.

Synthesis, Molecular Modeling of Novel Substituted Pyridazinones and their Vasorelaxant Activities

BACKGROUND

Hypertension, one of the most common cardiovascular diseases that can cause coronary disease, stroke, myocardial infarction, and sudden death, it is the major contributor to cardiac failure as well as renal insufficiency.

OBJECTIVES

As there are many cardio-active pyridazinone-base derivatives in clinical use, therefore, we aimed to synthesize a new series of pyridazin-3-ones and evaluate their vasorelaxant activity.

METHODS

A new series of synthesized compounds were carried out first by the synthesis of 6- flouroarylpyridazinones by cyclization of 3-(4-flourobenzoyl) propionic acid with hydrazine hydrate or arylhydrazines to provide the corresponding pyridazinone derivatives 2a-d. Mannich reaction was performed using morpholine or piperidine formaldehyde to obtain compounds 3a,b. On the other hand, reaction of 2a with various chloroacetamide intermediates, in dimethylformamide and potassium carbonate as a catalyst, afforded the target compounds 5a-c. The aromatic acid hydrazide intermediates 6a-g were prepared in 50-90% yield, by reacting to the prepared esters with hydrazine hydrate under reflux in ethanol. The two compounds 8a,b were prepared via condensation of 7a,b with ethyl chloroacetate in dry acetone. Finally, the target 2,4,6-trisubstituted pyridazinones 9a-c derivatives were obtained by the reaction of 7a with the appropriate aromatic aldehyde or substituted acetophenones. The new compounds were then evaluated for their vasorelaxant properties using isolated thoracic rat aortic rings. In addition, a homology model was built and molecular modeling simulation of these compounds into the active sites of the newly created α1a-adrenoceptor model was performed in order to predict and rationalize their affinities toward this receptor.

RESULTS

Among these compounds; 5a was the most potent, it exhibited approximately two-times the activity of prazosin (IC50 = 0.250, 0.487 mmol, respectively) also, fourteen compounds were more potent than prazosin.

Phthalazines and phthalazine hybrids as antimicrobial agents: Synthesis and biological evaluation

Phthalazine and phthalazinone derivatives are important owing to their significant biological activities and pharmacological properties. Herein, a benzoic acid derivative (2), a benzoxazin-1-one derivative (3), and an oxophthalazin-2(1 H)-yl)acetohydrazide (13) are utilized as precursors to construct a novel series of phthalazinones bearing various valuable functional groups in excellent yields via several simple and promising approaches. Finally, the antimicrobial activity of the newly synthesized phthalazines is screened against different microbial strains; namely, Gram-negative and Gram-positive bacteria utilizing Amoxicillin as a standard drug.

Discovery of new phthalazinones as vasodilator agents and novel pharmacological tools to study calcium channels

AIM

Hydralazine has led to the synthesis of phthalazinone derivatives which induce vasorelaxation.

METHODS

A new series of 2-(aminoalkyl)-4-benzyl-2H-phthalazin-1-one derivatives has been synthesized to study their vasorelaxant activity.

RESULTS

At the highest-studied concentration, most of the new compounds relaxed the denuded aortic rings precontracted with phenylephrine by 72.9-85.7%. Compound 25 (C25) suppressed almost totally the contractile effects of phenylephrine, high KCl concentration, ionomycin and caffeine related to the activation of Ca²⁺ channels, whereas its inhibitory effect was reversed with high CaCl₂ concentrations.

CONCLUSION

Vasodilator effects of C25 appear to be due exclusively to the reversible blockage of different calcium channels. As broad range calcium channel blocker, C25 seems to be suitable as a pharmacological tool for calcium channel research.

Facile synthetic approach towards vasorelaxant active 4-hydroxyquinazoline-4-carboxamides

A Facile synthetic approach is reported towards 4-hydroxyquinazoline-4-carboxamides 13a–i through ring expansion of 2,3-dioxoindoline-1-carboxamides 10a–c during secondary amine 11a–d nucleophilic reaction. Single crystal X-ray studies of 10c and 13d support the structures. Some of the synthesized quinazolinecarboxamides 13 show promising vasorelaxant properties with potency higher than that of Doxazosin through the pre-contracted (norepinephrine hydrochloride) rat aorta standard bioassay. Good molecular models (2D-QSAR, pharmacophore) describe the biological observations.

A set of vasorelaxant active 4-hydroxyquinazoline-4-carboxamides was obtained in a novel synthetic approach via secondary amine nucleophilic reaction with 2,3-dioxoindoline-1-carboxamides.

Overview of Antagonists Used for Determining the Mechanisms of Action Employed by Potential Vasodilators with Their Suggested Signaling Pathways

This paper is a review on the types of antagonists and the signaling mechanism pathways that have been used to determine the mechanisms of action employed for vasodilation by test compounds. Thus, we exhaustively reviewed and analyzed reports related to this topic published in PubMed between the years of 2010 till 2015. The aim of this paperis to suggest the most appropriate type of antagonists that correspond to receptors that would be involved during the mechanistic studies, as well as the latest signaling pathways trends that are being studied in order to determine the route(s) that atest compound employs for inducing vasodilation. The methods to perform the mechanism studies were included. Fundamentally, the affinity, specificity and selectivity of the antagonists to their receptors or enzymes were clearly elaborated as well as the solubility and reversibility. All the signaling pathways on the mechanisms of action involved in the vascular tone regulation have been well described in previous review articles. However, the most appropriate antagonists that should be utilized have never been suggested and elaborated before, hence the reason for this review.