Some novel layered-silicate nanocomposites based on a biodegradable hydroxybutyrate copolymer

This paper describes the preparation, characterization, mechanical properties and thermal stability of layered silicate nanocomposites based on poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHB-co-PHH, known as Nodax^TM). The dispersed phases were organically modified montmorillonites (clay 20A and clay 25A), mica, and talc, and they were introduced by solution mixing. Wide-angle X-ray scattering results and transmission electron microscopy (TEM) images confirmed that these two clays were intercalated and finely distributed in the Nodax^TM matrix. This type of layered filler led to remarkable improvements in mechanical properties even at very low loadings. Minimizing aggregation was more of a problem in the case of the mica and the talc, at least in this particular matrix. In some cases, these layered fillers slightly decreased the thermal stability of the Nodax^TM.     

HETEROCYCLIZATION OF AMINOTHIAZOLES

Several new 2-arylidinoamino-4-(3-coumaryl)thiazole derivatives were synthesized via the reaction of 2-amino-4-(coumaryl)thiazole with aromatic aldehydes and other reagents. Structural elucidations were based on elementary analysis and spectral data studies.     

CHEMISTRY OF UNCONDENSED 1,2,4-TRIAZINES: PART II-SULFUR CONTAINING 5-OXo-1,2,4-TRIAZIN-3-yl MOIETY AN OVERVIEW

Abstract

Studies on the chemical constituents of sulfur containing the 5-oxo-1,2,4-triazin-3-yl moiety are reviewed. The synthesis. unique features of the structures and biological significance of these constituents are discussed.     

Ionic liquid-supported chiral saldach with tunable hydrogen bonding: synthesis,metalation with Fe(III) and in vitro antimicrobial susceptibility

New water-soluble methylimidazolium ionic liquids (MIILs) bearing N,N′-bis-(salicylidene)-R,R-1,2-diaminocyclohexane (saldach) scaffold, H₂(R¹)₂saldach(2-MeIm⁺X⁻)₂ (4a: R¹=H, X=Cl^–; 4b: R¹=H, X=PF₆^–; 4c: R¹=H, X=BF₄^–; 4d: R¹=ⁱPr, X=Cl^–; 4e: R¹=ⁱPr, X=PF₆^–; 4f: R¹=ⁱPr, X=BF₄^–), and their Fe(III) complexes have been synthesized and structurally characterized as well as their profile of antimicrobial susceptibility was identified. The new saldach-supported MIILs demonstrated a distinctly enhanced biocidal effect toward methicillin resistant Staphylococcus aureus (MRSA) and multidrug-resistant Escherichia coli (MDREC). Compound 4d is the most potent antibacterial agent and could inhibit the growth of all micro-organisms, except A. flavus, more effectively than standard antibiotics.     

Identification of Potential SARS-CoV-2 Main Protease and Spike Protein Inhibitors from the Genus Aloe: An In Silico Study for Drug Development

Severe acute respiratory syndrome coronavirus (SARS-CoV-2) disease is a global rapidly spreading virus showing very high rates of complications and mortality. Till now, there is no effective specific treatment for the disease. Aloe is a rich source of isolated phytoconstituents that have an enormous range of biological activities. Since there are no available experimental techniques to examine these compounds for antiviral activity against SARS-CoV-2, we employed an in silico approach involving molecular docking, dynamics simulation, and binding free energy calculation using SARS-CoV-2 essential proteins as main protease and spike protein to identify lead compounds from Aloe that may help in novel drug discovery. Results retrieved from docking and molecular dynamics simulation suggested a number of promising inhibitors from Aloe. Root mean square deviation (RMSD) and root mean square fluctuation (RMSF) calculations indicated that compounds 132, 134, and 159 were the best scoring compounds against main protease, while compounds 115, 120, and 131 were the best scoring ones against spike glycoprotein. Compounds 120 and 131 were able to achieve significant stability and binding free energies during molecular dynamics simulation. In addition, the highest scoring compounds were investigated for their pharmacokinetic properties and drug-likeness. The Aloe compounds are promising active phytoconstituents for drug development for SARS-CoV-2.     

Phytochemical and Biological Evaluation of a Newly Designed Nutraceutical Self-Nanoemulsifying Self-Nanosuspension for Protection and Treatment of Cisplatin Induced Testicular Toxicity in Male Rats

The incorporation of cisplatin (CP) as a cytotoxic antineoplastic agent in most chemotherapeutic protocols is a challenge due to its toxic effect on testicular tissues. Natural compounds present a promising trend in research, so a new nutraceutical formulation (NCF) was designed to diminish CP spermatotoxicity. A combination of three nutraceutical materials, 250 mg Spirulina platensis powder (SP), 25 mg Tribulus terrestris L. extract (TT), and 100 mg fish oil (FO) were formulated in self-nanoemulsifying self-nanosuspension (SNESNS). SP was loaded into the optimized self-nanoemulsifying system (30% FO, 50% span 80/cremophor EL and 20% isopropanol) and mixed with TT aqueous solution to form SNESNS. For the SP, phytochemical profiling revealed the presence of valuable amounts of fatty acids (FAs), amino acids, flavonoids, polyphenols, vitamins, and minerals. Transmission electron microscopy (TEM) and particle size analysis confirmed the formation of nanoemulsion-based nanosuspension upon dilution. Method validation of the phytochemical constituents in NCF has been developed. Furthermore, NCF was biologically evaluated on male Wistar rats and revealed the improvement of spermatozoa, histopathological features, and biochemical markers over the CP and each ingredient group. Our findings suggest the potential of NCF with SNESNS as a delivery system against CP-induced testicular toxicity in male rats.     

Design and synthesis of new series of 3-cyanopyridine and pyrazolopyridine derivatives

Reaction of 3-cyano-4,6-dimethyl-2-pyridone with ethyl chloroacetate afforded ethyl 2-([3-cyano-4,6-dimethylpyridin-2-yl]oxy)acetate 2 and ethyl 2-(3-cyano-4,6-dimethyl-2-oxopyridin-1[2H]-yl)acetate 3 , the reaction product yield depend on the reaction condition (potassium carbonate concentration and reaction time). These compounds used as precursors to synthesize pyridine derivatives 4 , 6-10 , 15, 17-20 , furopyridines 5, 16 , pyrazolopyridine 12 , pyridopyrazolopyrimidines 14a,b . The structure of the newly synthesized compounds was confirmed by spectral data (IR, NMR, and mass spectra) and elemental analysis.     

The Sextic Centrifugal Distortion Terms for an Open-Shell Complex Consisting of a Diatomic Molecule in a (2S+1)Sigma Electronic State and a Closed-Shell Partner

An effective Hamiltonian for calculating rotational energy levels of an open-shell diatomic molecule, in a (2S+1)Sigma electronic state, weakly bonded to a closed-shell partner was presented (W. M. Fawzy, J. Mol. Spectrosc. 191, 68-80 (1998)). The Hamiltonian was given as H = H(ev) + H(rot) + H(sr) + H(ss) + H(cd) + H(srcd) + H(sscd), where all the quartic centrifugal distortion correction terms were included in the Hamiltonian term H(cd) but the sextic centrifugal distortion terms were ignored. This Hamiltonian is useful in cases where the complex has a well-defined equilibrium geometry and if the barrier to large-amplitude motion is large compared to the rotational constant of both the closed-shell molecule and its paramagnetic partner; if the barrier to large-amplitude motion is small compared to the rotational constant of one or both of the fragments, then a different treatment is required. In this paper, we introduce the new Hamiltonian terms H(sex(A))(cd) and H(sex(S))(cd), which represent the sextic centrifugal distortion correction terms for an asymmetric rotor. We also introduce all the nonvanishing matrix elements of each of the H(sex(A))(cd) and H(sex(S))(cd) operators. These operators and their matrix elements are required for calculating the rotational energy levels of relatively high J values in the described type of weakly bonded open-shell complexes. The terms H(sex(A))(cd) and H(sex(S))(cd) and their matrix elements are also valid for any stable asymmetric rotor in a nondegenerate electronic state. A brief discussion of the new Hamiltonian terms and their matrix elements is given. Copyright 2000 Academic Press.