7-Hydroxycoumarin Induces Vasorelaxation in Animals with Essential Hypertension: Focus on Potassium Channels and Intracellular Ca2+ Mobilization

Cardiovascular diseases (CVD) are the deadliest noncommunicable disease worldwide. Hypertension is the most prevalent risk factor for the development of CVD. Although there is a wide range of antihypertensive drugs, there still remains a lack of blood pressure control options for hypertensive patients. Additionally, natural products remain crucial to the design of new drugs. The natural product 7-hydroxycoumarin (7-HC) exhibits pharmacological properties linked to antihypertensive mechanisms of action. This study aimed to evaluate the vascular effects of 7-HC in an experimental model of essential hypertension. The isometric tension measurements assessed the relaxant effect induced by 7-HC (0.001 μM–300 μM) in superior mesenteric arteries isolated from hypertensive rats (SHR, 200–300 g). Our results suggest that the relaxant effect induced by 7-HC rely on K⁺-channels (K_ATP, BK_Ca, and, to a lesser extent, K_v) activation and also on Ca²⁺ influx from sarcolemma and sarcoplasmic reticulum mobilization (inositol 1,4,5-triphosphate (IP3) and ryanodine receptors). Moreover, 7-HC diminishes the mesenteric artery’s responsiveness to α1-adrenergic agonist challenge and improves the actions of the muscarinic agonist and NO donor. The present work demonstrated that the relaxant mechanism of 7-HC in SHR involves endothelium-independent vasorelaxant factors. Additionally, 7-HC reduced vasoconstriction of the sympathetic agonist while improving vascular endothelium-dependent and independent relaxation.     

Ultrasound-Assisted Water Extraction of Gentiopicroside,Isogentisin, and Polyphenols from Willow Gentian “Dust” Supported by Hydroxypropyl-β-Cyclodextrin as Cage Molecules

The residue after sieving (“dust”) from the willow gentian underground parts is an unexploited herbal tea by-product, although it contains valuable bioactive compounds. Cyclodextrins as efficient green co-solvents, cage molecules, and multifunctional excipients could improve the extraction and contribute to the added value of the resulting extracts. The objective of this study was to determine the optimal conditions for the extraction of gentiopicroside, isogentisin, and total phenolics (TPC) from willow gentian “dust” using ultrasound-assisted water extraction coupled with hydroxypropyl-β-cyclodextrin (HPβCD). The influence of extraction temperature (X₁: 20–80 °C), time (X₂: 20–50 min), and HPβCD concentration (X₃: 2–4% w/v) was analyzed employing the response surface methodology (RSM). The optimal extraction conditions for simultaneously maximizing the extraction yield of all monitored responses were X₁: 74.89 °C, X₂: 32.57 min, and X₃: 3.01% w/v. The experimentally obtained response values under these conditions (46.96 mg/g DW for gentiopicroside, 0.51 mg/g DW for isogentisin, and 12.99 mg GAE/g DW for TPC) were in close agreement with those predicted, thus confirming the suitability and good predictive accuracy of the developed RSM models. Overall, the developed extraction system could be an applicable alternative strategy to improve the extraction of bioactive compounds from the underutilized “dust” of willow gentian underground parts.     

Coordination Sites for Sodium and Potassium Ions in Nucleophilic Adeninate Contact ion-Pairs: A Molecular-Wide and Electron Density-Based (MOWED) Perspective

The adeninate anion (Ade⁻) is a useful nucleophile used in the synthesis of many prodrugs (including those for HIV AIDS treatment). It exists as a contact ion-pair (CIP) with Na⁺ and K⁺ (M⁺) but the site of coordination is not obvious from spectroscopic data. Herein, a molecular-wide and electron density-based (MOWED) computational approach implemented in the implicit solvation model showed a strong preference for bidentate ion coordination at the N3 and N9 atoms. The N3N9-CIP has (i) the strongest inter-ionic interaction, by −30 kcal mol⁻¹, with a significant (10–15%) covalent contribution, (ii) the most stabilized bonding framework for Ade⁻, and (iii) displays the largest ion-induced polarization of Ade⁻, rendering the N3 and N9 the most negative and, hence, most nucleophilic atoms. Alkylation of the adeninate anion at these two positions can therefore be readily explained when the metal coordinated complex is considered as the nucleophile. The addition of explicit DMSO solvent molecules did not change the trend in most nucleophilic N-atoms of Ade⁻ for the in-plane M-Ade complexes in M-Ade-(DMSO)₄ molecular systems. MOWED-based studies of the strength and nature of interactions between DMSO solvent molecules and counter ions and Ade⁻ revealed an interesting and unexpected chemistry of intermolecular chemical bonding.     

Antioxidant,Anti-Bacterial,and Congo Red Dye Degradation Activity of AgxO-Decorated Mustard Oil-Derived rGO Nanocomposites

Scaling up the production of functional reduced graphene oxide (rGO) and its composites requires the use of low-cost, simple, and sustainable synthesis methods, and renewable feedstocks. In this study, silver oxide-decorated rGO (Ag_xO−rGO) composites were prepared by open-air combustion of mustard oil, essential oil-containing cooking oil commercially produced from the seeds of Brassica juncea. Silver oxide (Ag_xO) nanoparticles (NPs) were synthesized using Coleus aromaticus leaf extract as a reducing agent. Formation of mustard seed rGO and Ag_xO NPs was confirmed by UV-visible characteristic peaks at 258 nm and 444 nm, respectively. rGO had a flake-like morphology and a crystalline structure, with Raman spectra showing clear D and G bands with an I_D/I_G ratio of 0.992, confirming the fewer defects in the as-prepared mustard oil-derived rGO (M−rGO). The rGO-Ag_xO composite showed a degradation efficiency of 81.9% with a rate constant k⁻¹ of 0.9506 min⁻¹ for the sodium salt of benzidinediazo-bis-1-naphthylamine-4-sulfonic acid (known as the azo dye Congo Red) in an aqueous solution under visible light irradiation. The composite also showed some antimicrobial activity against Klebsilla pneomoniae, Escherichia coli, and Staphylococcus aureus bacterial cells, with inhibition zones of ~15, 18, and 14 mm, respectively, for a concentration of 300 µg/mL. At 600 µg/mL concentration, the composite also showed moderate scavenging activity for 2,2-diphenyl-1-picrylhydrazyl of ~30.6%, with significantly lower activities measured for Ag_xO (at ~18.1%) and rGO (~8%) when compared to control.     

Synthesis of Starch-Grafted Polymethyl Methacrylate via Free Radical Polymerization Reaction and Its Application for the Uptake of Methylene Blue

In this research, a new biodegradable and eco-friendly adsorbent, starch-grafted polymethyl methacrylate (St-g-PMMA) was synthesized. The St-g-PMMA was synthesized by a free radical polymerization reaction in which methyl methacrylate (MMA) was grafted onto a starch polymer chain. The reaction was performed in water in the presence of a potassium persulfate (KPS) initiator. The structure and different properties of the St-g-PMMA was explored by FT-IR, 1H NMR, TGA, SEM and XRD. After characterization, the St-g-PMMA was used for the removal of MB dye. Different adsorption parameters, such as effect of adsorbent dose, effect of pH, effect of initial concentration of dye solution, effect of contact time and comparative adsorption study were investigated. The St-g-PMMA showed a maximum removal percentage (R%) of 97% towards MB. The other parameters, such as the isothermal and kinetic models, were fitted to the experimental data. The results showed that the Langmuir adsorption and pseudo second order kinetic models were best fitted to experimental data with a regression coefficient of R² = 0.93 and 0.99, respectively.     

Field-Induced Slow Magnetic Relaxation in CoII Cyclopropane-1,1-dicarboxylates

New Co^II substituted malonate field-induced molecular magnets {[Rb₆Co₃(cpdc)₆(H₂O)₁₂]∙6H₂O}_n (1) and [Cs₂Co(cpdc)₂(H₂O)₆]_n (2) (where cpdc²⁻ stands for cyclopropane-1,1-dicarboxylic acid dianions) were synthesized. Both compounds contain mononuclear bischelate fragments {Co^II(cpdc)₂(H₂O)₂}²⁻ where the quasi-octahedral cobalt environment (CoO₆) is complemented by water molecules in apical positions. The alkali metal atoms play the role of connectors between the bischelate fragments to form 3D and 2D polymeric structures for 1 and 2, respectively. Analysis of dc magnetic data using the parametric Griffith Hamiltonian for high-spin Co^II supported by ab initio calculations revealed that both compounds have an easy axis of magnetic anisotropy. Compounds 1 and 2 exhibit slow magnetic relaxation under an external magnetic field (H_DC = 1000 and 1500 Oe, respectively).     

Structural Diversity and Carbon Dioxide Sorption Selectivity of Zinc(II) Metal-Organic Frameworks Based on Bis(1,2,4-triazol-1-yl)methane and Terephthalic Acid

A three-component reaction between the 1,4-benzenedicarboxylic (terephthalic) acid (H₂bdc), bis(1,2,4-triazol-1-yl)methane (btrm) and zinc nitrate was studied, and three new coordination polymers were isolated by a careful selection of the reaction conditions. Coordination polymers {[Zn₃(DMF)(btrm)(bdc)₃]·nDMF}_∞ and {[Zn₃(btrm)(bdc)₃]·nDMF}_∞ containing trinuclear {Zn₃(bdc)₃} secondary building units are joined by btrm auxiliary linkers into three-dimensional metal–organic frameworks. The coordination polymer {[Zn(bdc)(btrm)]∙nDMF}_∞ consists of Zn²⁺ cations joined by bdc²⁻ and btrm linkers into a two-fold interpenetrated network. Upon activation, MOF [Zn₃(btrm)(bdc)₃]_∞ demonstrated CO₂/N₂ adsorption selectivity with an ideal adsorbed solution theory (IAST) factor of 21. All three MOF demonstrated photoluminescence with a maximum near 435–440 nm upon excitation at 330 nm.     

Broadband Multidimensional Spectroscopy Identifies the Amide II Vibrations in Silkworm Films

We used two-dimensional infrared spectroscopy to disentangle the broad infrared band in the amide II vibrational regions of Bombyx mori native silk films, identifying the single amide II modes and correlating them to specific secondary structure. Amide I and amide II modes have a strong vibrational coupling, which manifests as cross-peaks in 2D infrared spectra with frequencies determined by both the amide I and amide II frequencies of the same secondary structure. By cross referencing with well-known amide I assignments, we determined that the amide II (N-H) absorbs at around 1552 and at 1530 cm^–1 for helical and β-sheet structures, respectively. We also observed a peak at 1517 cm⁻¹ that could not be easily assigned to an amide II mode, and instead we tentatively assigned it to a Tyrosine sidechain. These results stand in contrast with previous findings from linear infrared spectroscopy, highlighting the ability of multidimensional spectroscopy for untangling convoluted spectra, and suggesting the need for caution when assigning silk amide II spectra.     

Eco-Friendly Synthesis of an Oxovanadium(IV)-bis(abietate) Complex with Antimicrobial Action

The search for less expensive and viable products is always one of the challenges for research development. Commonly, the synthesis of coordination compounds involves expensive ligands, through expensive and low-yield routes, in addition to generating toxic and unusable residues. In this work, the organic ligand used is derived from the resin of a reforestation tree, Pinus elliottii var. elliottii. The synthesis method used Pinus resin and an aqueous solution of vanadium(III) chloride at a temperature of 80 °C. The procedure does not involve organic solvents and does not generate toxic residues, thus imparting the complex formation reaction a green chemistry character. The synthesis resulted in an unprecedented oxovanadium(IV)-bis(abietate) complex, which was characterized by mass spectrometry (MS), chemical analysis (CHN), vibrational (FTIR) and electronic spectra (VISIBLE), X-ray diffraction (XRD), and thermal analysis (TG/DTA). Colorimetric studies were performed according to the CIELAB color space. The structural formula found, consisted of a complex containing two abietate ligands, [VO(C₂₀H₂₉O₂)₂]. The VO(IV)-bis(abietate) complex was applied against microorganisms and showed promising results in antibacterial and antifungal activity. The best result of inhibitory action was against the strains of Gram-positive bacteria S. aureus and L. monocytogenes, with minimum inhibitory concentration (MIC) values of 62.5 and 125 μmol L⁻¹, respectively. For Gram-negative strains the results were 500 μmol L⁻¹ for E. coli; and 1000 μmol L⁻¹ for Salmonella enterica Typhimurium. Antifungal activity was performed against Candida albicans, where the MIC was 15.62 μmol L⁻¹, and for C. tropicalis it was 62.5 μmol L⁻¹. According to the MFC analysis, the complex presented, in addition to the fungistatic action, a fungicidal action, as there was no growth of fungi on the plates tested. The results found for the tests demonstrate that the VO(IV)-bis(abietate) complex has great potential as an antimicrobial and mainly antifungal agent. In this way, the pigmented ink with antimicrobial activity could be used in environments with a potential risk of contamination, preventing the spread of microorganisms harmful to health.     

Deep Eutectic Solvents: Alternative Solvents for Biomass-Based Waste Valorization

Innovative technologies can transform what are now considered “waste streams” into feedstocks for a range of products. Indeed, the use of biomass as a source of biopolymers and chemicals currently has a consolidated economic dimension, with well-developed and regulated markets, in which the evaluation of the manufacturing processes relies on specific criteria such as purity and yield, and respects defined regulatory parameters for the process safety. In this context, ionic liquids and deep eutectic solvents have been proposed as environmentally friendly solvents for applications related to biomass waste valorization. This mini-review draws attention to some recent advancements in the use of a series of new-solvent technologies, with an emphasis on deep eutectic solvents (DESs) as key players in the development of new processes for biomass waste valorization. This work aims to highlight the role and importance of DESs in the following three strategic areas: chitin recovery from biomass and isolation of valuable chemicals and biofuels from biomass waste streams.