6-Arylamino-5,8-quinazolinediones as potent inhibitors of endothelium-dependent vasorelaxation

Exploration of brominated Plastoquinone analogs: Discovery and structure-activity relationships of small antimicrobial lead molecules

In the fight with the antimicrobial resistance, our continuous effort to find quinone analogs with higher inhibitory activity has previously led us to the promising Plastoquinone analogs. The 1,4-quinone moiety substituted with alkoxy substituent(s) plays an important role in the field of antimicrobial and anticancer drug discovery and development. Thus, an extensive series of 1,4-quinones, substituted in different positions with a variety of alkoxy substituents, has been designed, synthesized, and evaluated for their antimicrobial activity. Here, we describe the synthesis of brominated Plastoquinone analogs (BrPQ1-15) based on the dimethyl-1,4-quinone scaffold by employing two different paths. We also present here the in vitro antimicrobial activity of these analogs (BrPQ1-15) against a panel of pathogenic organisms. These studies resulted in several new selective antibacterial inhibitors and gave valuable insights into the structure-activity relationships. Among all the analogs studied, two analogs BrPQ1 with a methoxy substituent and BrPQ14 with a cyclic dioxy stand out as the most promising antibacterial molecules against Staphylococcus aureus and Staphylococcus epidermidis. Afterwards, two analogs were selected for a further investigation for biofilm evaluation. Finally, molecular docking studies for BrPQ1 and BrPQ14 with probable target S. aureus PNPase (5XEX) and predictive ADMET studies were also carried out.

Impact of the Potential Antitumor Agent 2-(4-Hydroxyphenyl) Amino-1,4-Naphthoquinone (Q7) on Vasomotion Is Mediated by the Vascular Endothelium, But Not Vascular Smooth Muscle Cell Metabolism

ABSTRACT

Vasomotion is defined as rhythmic oscillations in arterial diameter that regulate the blood flow and blood pressure. Because antitumor treatment may impair vascular functions and increase the blood pressure, we sought to evaluate whether a new naphthoquinone derivative, postulated as an antitumor agent, manifests adverse effects on vascular function. In this article, we evaluated the toxicity of 2-(4-hydroxyphenyl) amino-1,4-naphthoquinone (Q7) and its effects on vascular vasomotion in 3 models of vascular structure: endothelial cells, aortic ring, and smooth muscle cells. Although showing nontoxic effects, Q7 inhibited the formation of capillary-like structures of the EA.hy926 endothelial cell line grown on Matrigel. In exvivo experiments with aortic rings precontracted with phenylephrine (PE, 10-6 M), Q7 (10-5 M) significantly (P < 0.05) reduced vascular rhythmic contractions induced by the acetylcholine (ACh; 10-7-10-5 M), whereas sodium nitroprusside (a nitric oxide donor; 10-8 M) recovered the vasomotion. Furthermore, Q7 (10-5 M) did not decrease KCl-induced vascular rhythmic contractions in the aortic rings precontracted with BaCl2 (a nonselective K+ channel blocker; 10-3 M). Vascular smooth muscle cells (A7r5) preincubated with Q7 (10-5 M) for 3 hours also demonstrated a reduced glucose uptake. However, the Adenosine Triphosphate content was unaffected, suggesting that the rapid reduction in vasomotion observed in vascular reactivity experiments did not involve cellular metabolism but may be due to faster mechanisms involving endothelial nitric oxide and K+ channels leading to oscillations in intracellular Ca2+. In summary, the naphthoquinone derivative Q7 presents low cytotoxicity yet may alter the endothelial cell response and vasomotion in the absence of changes in smooth muscle cell metabolism.

Modulatory Effect of 2-(4-Hydroxyphenyl)amino-1,4-naphthoquinone on Endothelial Vasodilation in Rat Aorta

The vascular endothelium plays an essential role in the control of the blood flow. Pharmacological agents like quinone (menadione) at various doses modulate this process in a variety of ways. In this study, Q7, a 2-phenylamino-1,4-naphthoquinone derivative, significantly increased oxidative stress and induced vascular dysfunction at concentrations that were not cytotoxic to endothelial or vascular smooth muscle cells. Q7 reduced nitric oxide (NO) levels and endothelial vasodilation to acetylcholine in rat aorta. It also blunted the calcium release from intracellular stores by increasing the phenylephrine-induced vasoconstriction when CaCl₂ was added to a calcium-free medium but did not affect the influx of calcium from extracellular space. Q7 increased the vasoconstriction to BaCl₂ (10⁻³ M), an inward rectifying K⁺ channels blocker, and blocked the vasodilation to KCl (10⁻² M) in aortic rings precontracted with BaCl₂. This was recovered with sodium nitroprusside (10⁻⁸ M), a NO donor. In conclusion, Q7 induced vasoconstriction was through a modulation of cellular mechanisms involving calcium fluxes through K⁺ channels, and oxidative stress induced endothelium damage. These findings contribute to the characterization of new quinone derivatives with low cytotoxicity able to pharmacologically modulate vasodilation.

Synthesis of 3-N-sugar-substituted-2, 4(1H,3H)-quinazolinedionesas anti-angiogenesis agents

A series of novel 3-N-sugar-substituted quinazolinediones were synthesized through the cyclization of the intermediate 2-aminobenzamides using triphosgene as the condensing reagent. Their anti-angiogenesis activities were investigated. The compound 3-(2'-aminoglucosyl)-2,4-(1H,3H)-quinazolinedione, (5d) showed good anti-angiogenesis activity.

Synthesis and antifungal activity of 5,8-quinazolinedione derivatives modified at positions 6 and 7

5,8-Quinazolinediones modified at positions 6 and 7 were synthesized and tested for in vitro antifungal activities against Candida species and Aspergillus niger. Most of 5,8-quinazolinediones 3-5 generally exhibited potent antifungal activity. 6-Arylamino-7-chloro-5,8-quinazolinediones (3) generally showed more potent antifungal activity than 7-arylthio-5,8-quinzolinediones (4) and 6,7-bis-(arylthio)-5,8-quinazolinediones (5).

QSAR study of quinolinediones with inhibitory activity of endothelium-dependent vasorelaxation by CoMSIA

The 3D-QSAR study of quinolinediones which showed potent inhibitory effect on the acetylcholine induced vasorelaxation of rat aorta with the endothelium was conducted by CoMSIA. The statistical result, cross-validated q(2) (0.741) and r(2) (0.960) values, gave reliability to the prediction of inhibitory activity of this series.