Theoretical characterization of the chemical bonds of some three-membered ring compounds through QTAIM theory

Structural Chemistry - In this paper, we investigate the nature of the carbonyl and the intraring C–C, C–N, C–O, N–N, O–O and N–O bonds of cyclopropanone and the...     

Inflammatory responses of a human keratinocyte cell line to 10 nm citrate- and PEG-coated silver nanoparticles

Silver nanoparticles (AgNPs) are among the most commonly used engineered NPs and various commercially available products are designed to come in direct contact with the skin (wound dressings, textiles, creams, among others). Currently, there is limited understanding of the influence of coatings on the toxicity of AgNPs and in particular their ability to impact on AgNP’s mediated inflammatory responses. As AgNPs are often stabilized by different coatings, including citrate and polyethyleneglycol (PEG), in this study we investigate the influence of citrate (Cit10) or PEG (PEG10) coatings to 10 nm AgNP on skin, using human HaCaT keratinocytes. AgNPs cytotoxicity and inflammatory response (nuclear factor (NF)-κB induction and cytokine production) of HaCaT were assessed after in vitro exposure to 10 and 40 µg/mL after 4, 24, and 48 h. Results showed that although both types of coated AgNPs decreased cell proliferation and viability, Cit10 AgNPs were more toxic. NF-κB inhibition was observed for the highest concentration (40 µg/mL) of PEG10 AgNPs, and the putative link to early apoptotic pathways observed in these cells is discussed. No production of IL-1β, IL-6, IL-10, and TNFα was stimulated by AgNPs. Furthermore, Cit10 and PEG10 AgNPs decreased the release of MCP-1 by HaCaT cells after 48 h of exposure. As cytokines are vital for the immunologic regulation in the human body, and it is demonstrated that they may interfere with NPs, more research is needed to understand how different AgNPs affect the immune system.     

Lagaspholones A and B: two new jatropholane-type diterpenes from Euphorbia lagascae

[structure: see text] Two new diterpenes, lagaspholones A (1) and B (2), have been isolated from the methanolic extract of Euphorbia lagascae, along with the known compounds (+)-dehydrovomifoliol, scopoletin, dehydrodiconiferyl diacetate, 3-indolcarbaldehyde, and 4-hydroxy-3,5-dimethoxybenzaldehyde. Their structures were elucidated by spectroscopic methods. Compounds 1 and 2 contain the rare jatropholane-type skeleton, characterized by a 5:6:7:3 fused ring system. A possible biosynthetic pathway for lagaspholones is proposed.     

A new process for acrylic acid synthesis by fermentative process

With the synthesis of chemical products through biotechnological processes, it is possible to discover and to explore innumerable routes that can be used to obtain products of high added value. Each route may have particular advantages in obtaining a desired product, compared with others, especially in terms of yield, productivity, easiness to separate the product, economy, and environmental impact. The purpose of this work is the development of a deterministic model for the biochemical synthesis of acrylic acid in order to explore an alternative process. The model is built-up with the tubular reactor equations together with the kinetic representation based on the structured model. The proposed process makes possible to obtain acrylic acid continuously from the sugar cane fermentation.     

Complexation of transition metals by 3-azidopropionitrile. An electrospray ionization mass spectrometry study

Most complexes of azides and transition metals involve the N(3)(-) azide anion as a ligand other than an organic azide. Complexes of organic azides with metals are involved in biological applications and in the deposition of nitrenes on metal surfaces, producing nitride layers for semi-conductors preparation; this makes the study of these interactions an important issue. This work describes a study of the complexation of nickel and cobalt by 3-azidopropionitrile by means of electrospray ionization mass spectrometry (ESI-MS). Complexes were obtained from solutions of NiCl(2) and CoCl(2) in methanol/water. In the case of nickel, other NiX(2) salts were investigated (where X = Br or NO(3)) and other solvents were also studied (notably ethanol/water). All complexes detected were single positively charged, with various stoichiometries, some resulted from the fragmentation of the ligand, the loss of N(2), and HCN being quite common. The most abundant cations observed were [Ni(II)AzAzX](+), where X = Cl, Br, NO(3). Some of the complexes showed solvation with methanol/ethanol/water. Metal reduction was observed in complexes where a radical was lost, resulting from the homolytic cleavage of a metal-nitrogen bond. Collision induced dissociation (CID) experiments followed by tandem mass spectrometry (MS-MS) analysis were not absolutely conclusive about the coordination site. However, terminal ions observed from the fragmentation routes were explained by a proposed gas-phase mechanism. Density functional theory calculations were carried out and provided structures for some complexes, pointing to the possibility of 3-azidopropionitrile acting as a mono- or a bidentate ligand.     

Multiparticle correlations in resonance-matter formation

The effect of multiparticle correlations on resonance and pion populations, in relativistic nuclear reactions, is calculated in the context of an intranuclear cascade model which includes N-body (N > 2) collisional processes. The resonance-matter population present in the highly-compressed phase of nucleus-nucleus collisions is investigated, in reactions between different intermediate-mass nuclear systems. Received: 29 December 1998 / Revised version: 20 December 1999     

Catechins: Therapeutic Perspectives in COVID-19-Associated Acute Kidney Injury

Data obtained from several intensive care units around the world have provided substantial evidence of the strong association between impairment of the renal function and in-hospital deaths of critically ill COVID-19 patients, especially those with comorbidities and requiring renal replacement therapy (RRT). Acute kidney injury (AKI) is a common renal disorder of various etiologies characterized by a sudden and sustained decrease of renal function. Studies have shown that 5–46% of COVID-19 patients develop AKI during hospital stay, and the mortality of those patients may reach up to 100% depending on various factors, such as organ failures and RRT requirement. Catechins are natural products that have multiple pharmacological activities, including anti-coronavirus and reno-protective activities against kidney injury induced by nephrotoxic agents, obstructive nephropathies and AKI accompanying metabolic and cardiovascular disorders. Therefore, in this review, we discuss the anti-SARS-CoV-2 and reno-protective effects of catechins from a mechanistic perspective. We believe that catechins may serve as promising therapeutics in COVID-19-associated AKI due to their well-recognized anti-SARS-CoV-2, and antioxidant and anti-inflammatory properties that mediate their reno-protective activities.     

Solvent Mixture Optimization in the Extraction of Bioactive Compounds and Antioxidant Activities from Garlic (Allium sativum L.)

Garlic is a health promoter that has important bioactive compounds. The bioactive extraction is an important step in the analysis of constituents present in plant preparations. The purpose of this study is to optimize the extraction with the best proportion of solvents to obtain total phenolic compounds (TPC) and thiosulfinates (TS) from dried garlic powder, and evaluate the antioxidant activities of the optimized extracts. A statistical mixture simplex axial design was used to evaluate the effect of solvents (water, ethanol, and acetone), as well as mixtures of these solvents, after two ultrasound extraction cycles of 15 min. Results showed that solvent mixtures with a high portion of water and pure water were efficient for TPC and TS recovery through this extraction procedure. According to the regression model computed, the most significant solvent mixtures to obtain high TPC and TS recovery from dried garlic powder are, respectively, the binary mixture with 75% water and 25% acetone and pure water. These optimized extracts presented oxygen radical absorbance capacity. Pure water was better for total antioxidant capacity, and the binary mixture of water–acetone (75:25) was better for DPPH scavenging activity. These optimized extracts can be used for industrial and research applications.     

Copper and iron interactions with angiotensin-converting enzyme inhibitors. A study by fast-atom bombardment tandem mass spectrometry

Fast atom bombardment, combined with high-energy collision-induced tandem mass spectrometry, has been used to investigate gas-phase metal-ion interactions with captopril, enalaprilat and lisinopril, all angiotensin-converting enzyme inhibitors.Suggestions for the location of metal-binding sites are presented. For captopril, metal binding occurs most likely at both the sulphur and the nitrogen atom. For enalaprilat and lisinopril, binding preferably occurs at the amine nitrogen. Copyright 1999 John Wiley & Sons, Ltd.     

Evidence of the Presence of Dimethylated,Trimethylated and "Refractory' Arsenic Compounds in Estuarine Salt-marsh Halophytes

Five species of halophytes were sampled in the salt marshes of the Tagus estuary, dried, ground and digested. They were further extracted with ethanol and the extracts passed through weak and strong cationic ion-exchange resins, purified through TLC and submitted to pyrolysis mass spectrometry and HPLC–ICP/MS. Arsenic content and hydride-forming arsenic species were verified, in each step, by GF–AA and HG–QFAA. A high content of arsenic was found in the samples of halophytes studied, both di- and tri-methylated arsenic compounds being present. A considerable fraction of this arsenic content seems to be refractory to hydride generation. Moreover, the arsenic fraction found seems to have the same ion-exchange behaviour as the refractory fractions formerly studied in estuarine water. A partial characterization of these structures by pyrolysis–GC–MS suggests the presence of arsenobetaine and arsenocholine compounds. Furthermore, HPLC–ICP/MS data seem to confirm the presence of these compounds. In addition, the latter hyphenated technique strongly suggests the presence of a number of other organoarsenicals including tetramethylarsonium (TMAs), trimethylarsine oxide (TMAO), cacodylate (DMA) and possibly an arsenosugar-type compound. © 1997 by John Wiley & Sons, Ltd.