A prominent C-acylation-cyclisation synthetic sequence and X-ray structure elucidation of benzothiopyranone derivatives

A novel short-step methodology to benzothiopyranone derivatives has been developed starting from an activated precursor, N-hydroxysuccinimide ester of thiosalicylic acid. The procedure is based on a tandem C-acylation-cyclisation process under mild reaction conditions in good yields. The structure elucidation has been established using X-ray crystallography and NMR spectral data. © 2008 Elsevier Ltd. All rights reserved

Regioselective ring opening of thiomalic acid anhydrides by carbon nucleophiles. Synthesis and X-ray structure elucidation of novel thiophenone derivatives

Novel and promising thiophenone derivatives were synthesised by regioselective ring opening of activated thiomalic acid anhydrides, with a variety of active methylene nucleophiles via a C-acylation/cyclisation process involving an S-C bond formation. This regioselective approach could be moreover established by X-ray diffraction structure analysis. The thiolactone ring can act as valuable synthetic scaffold for the preparation of natural and synthetic compounds with important biological and pharmacological activities. © 2009 Elsevier Ltd. All rights reserved

Encapsulation of oregano (Origanum onites l.) essential oil in β-cyclodextrin (β-CD): Synthesis and characterization of the inclusion complexes

The aim of the present work was to study the encapsulation of Origanum onites L. essential oil (oregano EO) in β-cyclodextrin (β-CD) inclusion complexes (ICs), using the co-precipitation method. The formed β-CD–oregano EO ICs were characterized by diverse methods, such as Dynamic Light Scattering (DLS), FT-IR spectroscopy, Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA), Nuclear Magnetic Resonance (NMR) spectroscopy and Scanning Electron Microscopy (SEM). UV-Vis spectroscopy was used for the determination of the inclusion efficacy and the study of the encapsulated oregano EO release profile. The interactions between host (β-CD) and guest (oregano EO) in the formed ICs were proven by the FT-IR, DSC, TG and NMR analyses. The ICs, which derived from different batches, presented nanoscale size (531.8 ± 7.7 nm and 450.3 ± 11.5 nm, respectively), good size dispersion (0.308 ± 0.062 and 0.484 ± 0.029, respectively) and satisfactory stability in suspension (ζ-potential = −21.5 ± 1.2 mV and −30.7 ± 1.8 mV). Inclusion efficiency reached up to 26%, whereas the oregano EO release from the ICs followed a continuous delivery profile for up to 11 days, based on in vitro experiments. The formed ICs can find diverse applications, such as in the preparation of films for active packaging of food products, in personal care products for the improvement of their properties (e.g., antioxidant, antimicrobial, etc.), as well as in insect repellent products. © 2017 by the authors. Licensee MDPI, Basel, Switzerland

Volatile Components of Heartwood, Sapwood, and Resin from a Dated Cedrus brevifolia

In the present study, the heartwood and the sapwood of a thick wood disc from a dated Cedrus brevifolia trunk, and the resin were analyzed for their volatile components. All samples were subjected to headspace solid-phase microextraction followed by gas chromatography mass spectrometry analysis. The main constituents were β-himachalene (22.2 %) in heartwood and (25.0 %) in sapwood, and α-pinene (37.8 %) in resin. © The Author(s) 201

Coordination behavior of 3-Ethoxycarbonyltetronic acid towards Cu(II) and Co(II) metal ions

Tetronic acids, 4-hydroxy-5H-furan-2-ones, constitute a class of heterocyclic compounds with potent biological and pharmacological activity. The , -tricarbonyl moiety plays an integral role in biological systems and forms a variety of metal complexes. In this report, we present the complexation reactions of 3-ethoxycarbonyl tetronic acids with acetates and chlorides of Cu(II) and Co(II). These complexes have been studied by means of EPR spectroscopy and magnetic susceptibility measurements. From the obtained results, a preliminary complexation mode of the ligand is proposed

Development and characterization of eudragit®-based electrospun nanofibrous mats and their formulation into nanofiber tablets for the modified release of furosemide

Furosemide, a chloride channel blocker ordinarily used as a high-ceiling or loop diuretic, is practically insoluble in water and dilute acids. Due to its acidic nature, furosemide is mostly absorbed in the stomach and in the upper small intestine. Efforts have focused on the development of sustained release systems of furosemide in order to improve the effectiveness of the drug, which exhibits poor aqueous solubility and poor permeability. Recently, electrospun nanofibrous drug delivery systems have emerged as promising alternative solid-dosage forms due to their advantages of high porosity, high surface to volume ratio, and high drug-loading efficacy. Herein, a number of nanofibrous mats composed of different types of Eudragit® polymers in various concentrations and combinations loaded with furosemide were designed, successfully electrospun, and characterized using SEM, FTIR, DSC, and TGA analyses. The nanofibrous nonwovens were formulated in nanofiber tablets and the release profile of furosemide from them was evaluated at pH 1.2 and 6.8 and compared to that of physical mixture matrix tablets of analogous composition as well as to that of a commercial formulation. It was found that the release of furosemide was compatible with the gastroretentive and slower intestinal release requirements with a well-defined absorption window, while some nanofiber formulations could act as furosemide carriers in emergency situations where a relatively fast onset of its action is required, as in the case of critically ill post-traumatic patients. © 2019 by the authors. Licensee MDPI, Basel, Switzerland

Synthesis and antifouling activity evaluation of analogs of bromosphaerol, a brominated diterpene isolated from the red Alga Sphaerococcus coronopifolius

Marine biofouling is an epibiotic biological process that affects almost any kind of submerged surface, causing globally significant economic problems mainly for the shipping industry and aquaculture companies, and its prevention so far has been associated with adverse environmental effects for non-target organisms. Previously, we have identified bromosphaerol (1), a brominated diterpene isolated from the red alga Sphaerococcus coronopifolius, as a promising agent with significant antifouling activity, exerting strong anti-settlement activity against larvae of Amphibalanus (Balanus) amphitrite and very low toxicity. The significant antifouling activity and low toxicity of bromosphaerol (1) motivated us to explore its chemistry, aiming to optimize its antifouling potential through the preparation of a number of analogs. Following different synthetic routes, we successfully synthesized 15 structural analogs (2–16) of bromosphaerol (1), decorated with different functional groups. The anti-settlement activity (EC50) and the degree of toxicity (LC50) of the bromosphaerol derivatives were evaluated using cyprids and nauplii of the cirriped crustacean A. amphitrite as a model organism. Derivatives 2, 4, and 6–16 showed diverse levels of antifouling activity. Among them, compounds 9 and 13 can be considered as well-performing antifoulants, exerting their activity through a non-toxic mechanism. © 2021 by the authors. Licensee MDPI, Basel, Switzerland