First novel synthesis of triazole thioglycosides as ribavirin analogues

This study reports a novel and efficient method for the synthesis of the first reported novel class of triazole thioglycosides. These series of compounds were designed through the reaction of potassium cyanocarbonimidodithioate 2 with hydrazine derivatives 3a-d in EtOH at room temperature to give the corresponding potassium 5-amino-1H-1,2,4-triazole-3-thiolates 4a-d. The latter compounds were treated with tetra-O-acetyl-α-D-glucopyranosyl bromide 6a and tetra-O-acetyl-α-D-galactopyranosyl bromide 6b in DMF at room temperature to give in high yields the corresponding triazole thioglycosides 7a-h. Treatment of triazole salts 4a–d with hydrochloric acid afforded the corresponding 3-mercaptotriazoles 5a-d. Compounds 5a-d were then reacted with bromoperacetylated sugars 6a,b in sodium hydride-DMF at ambient temperature to afford the thioglycosyl compounds 7a-h. Ammonolysis of the triazole thioglycosides 7a-h afforded the corresponding free thioglycosides 8a-h. The scope and limitation of the method is demonstrated. The structure of the reaction products was confirmed on the basis of their elemental analysis and spectral data (IR, ¹H NMR, MS and ¹³C NMR).     

Novel chalcone/aryl carboximidamide hybrids as potent anti-inflammatory via inhibition of prostaglandin E2 and inducible NO synthase activities: design,synthesis, molecular docking studies and ADMET prediction

Two series of chalcone/aryl carboximidamide hybrids 4a–f and 6a–f were synthesised and evaluated for their inhibitory activity against iNOS and PGE2. The most potent derivatives were further checked for their in vivo anti-inflammatory activity utilising carrageenan-induced rat paw oedema model. Compounds 4c, 4d, 6c and 6d were proved to be the most effective inhibitors of PGE2, LPS-induced NO production, iNOS activity. Moreover, 4c, 4d, 6c and 6d showed significant oedema inhibition ranging from 62.21% to 78.51%, compared to indomethacin (56.27 ± 2.14%) and celecoxib (12.32%). Additionally, 4c, 6a and 6e displayed good COX2 inhibitory activity while 4c, 6a and 6c exhibited the highest 5LOX inhibitory activity. Compounds 4c, 4d, 6c and 6d fit nicely into the pocket of iNOS protein (PDB ID: 1r35) via the important amino acid residues. Prediction of physicochemical parameters exhibited that 4c, 4d, 6c and 6d had acceptable physicochemical parameters and drug-likeness. The results indicated that chalcone/aryl carboximidamides 4c, 4d, 6c and 6d, in particular 4d and 6d, could be used as promising lead candidates as potent anti-inflammatory agents.     

Biochemical studies of the multicopper oxidase (small laccase) from Streptomyces coelicolor using bioactive phytochemicals and site‐directed mutagenesis

Multicopper oxidases can act on a broad spectrum of phenolic and non‐phenolic compounds. These enzymes include laccases, which are widely distributed in plants and fungi, and were more recently identified in bacteria. Here, we present the results of biochemical and mutational studies of small laccase (SLAC), a multicopper oxidase from Streptomyces coelicolor (SCO6712). In addition to typical laccase substrates, SLAC was tested using phenolic compounds that exhibit antioxidant activity. SLAC showed oxidase activity against 12 of 23 substrates tested, including caffeic acid, ferulic acid, resveratrol, quercetin, morin, kaempferol and myricetin. The kinetic parameters of SLAC were determined for 2,2′‐azino‐bis(3‐ethylbenzthiazoline‐6‐sulphonic acid), 2,6‐dimethoxyphenol, quercetin, morin and myricetin, and maximum reaction rates were observed with myricetin, where k_cat and K_m values at 60°C were 8.1 (± 0.8) s^?1 and 0.9 (± 0.3) mM respectively. SLAC had a broad pH optimum for activity (between pH 4 and 8) and temperature optimum at 60–70°C. It demonstrated remarkable thermostability with a half‐life of over 10 h at 80°C and over 7 h at 90°C. Site‐directed mutagenesis revealed 17 amino acid residues important for SLAC activity including the 10 His residues involved in copper coordination. Most notably, the Y229A and Y230A mutant proteins showed over 10‐fold increase in activity compared with the wild‐type SLAC, which was correlated to higher copper incorporation, while kinetic analyses with S929A predicts localization of this residue near the meta‐position of aromatic substrates.     

Effect of Antiadherents on the Physical and Drug Release Properties of Acrylic Polymeric Films

Antiadherents are used to decrease tackiness of a polymer coating during both processing and subsequent storage. Despite being a common excipient in coating formulae, antiadherents may affect mechanical properties of the coating film as well as drug release from film-coated tablets, but how could addition of antiadherents affect these properties and to what extent and is there a relation between the physical characteristics of the tablet coat and the drug release mechanisms? The aim of this study was to evaluate physical characteristics of films containing different amounts of the antiadherents talc, glyceryl monostearate, and PlasACRYL^TM T20. Eudragit RL30D and Eudragit RS30D as sustained release polymers and Eudragit FS30D as a delayed release material were used. Polymer films were characterized by tensile testing, differential scanning calorimetry (DSC), microscopic examination, and water content as calculated from loss on drying. The effect of antiadherents on in vitro drug release for the model acetylsalicylic acid tablets coated with Eudragit FS30D was also determined. Increasing talc concentration was found to decrease the ability of the polymer films to resist mechanical stress. In contrast, glyceryl monostearate (GMS) and PlasACRYL produced more elastic films. Talc at concentrations higher than 25% caused negative effects, which make 25% concentration recommended to be used with acrylic polymers. All antiadherents delayed the drug release at all coating levels; hence, different tailoring of drug release may be achieved by adjusting antiadherent concentration with coating level.     

Changes in nitrogen content and protein profiles following <Emphasis Type="Italic">in vitro</Emphasis> selection of NaCl resistant mung bean and tomato

Mung bean and tomato were in vitro selected on media containing 0, 25, 50, 100 and 150 mM NaCl. Two types of media (hormone supplemented media, CB and hormone free media, MS) were used for mung bean using cotyledon explants whereas two types of explants (cotyledons and shoot apices) were used for tomato on MS media. Total-N, protein content, nitrite reductase (NiR) activity and protein protein profiles were checked in selected plants and compared to original non selected ones. NaCl at low concentrations slightly increased total-N in shoots and roots of in vitro selected mung bean and tomato whereas higher concentrations induced significant reductions. Similar increases in protein content were detected at lower concentrations with no significant effects thereover. On the contrary, NaCl gradually inhibited NiR activity. Similar responses of total-N, protein and NiR activity, but with greater magnitudes, were detected in original plants. In addition, NaCl significantly reduced dry weights of shoots and roots of either in vitro selected or, in particular, original intact plants. Moreover, electrophoresis (SDS-PAGE) of protein from shoots of either in vitro selected or intact plants showed that NaCl induced new protein bands while some others were concomitantly disappeared. The induction of one or more of the 86.4, 79, 77.6, 77 and 71.5 kDa bands following in vitro selection and/or the disappearance of the 86 kDa band from intact plants seemed necessary for mung bean resistance. Also, the presence of 86.2 kDa band and/or the loss of the 85.8 and 57.5 kDa bands might be included in tomato resistance. Of these induced bands in mung bean selected on CB media, only two bands were detected in plants selected on MS media. In tomato, two bands lost following selection from cotyledons but only one band lost following selection from shoot apices. These changes in protein pattern therefore might serve as adaptive regulators for resistance to NaCl.     

Tablet formulation containing meloxicam and β-cyclodextrin: Mechanical characterization and bioavailability evaluation

The purpose of this research was to evaluate β-cyclodextrin (β-CD) as a vehicle, either singly or in blends with lactose (spray-dried or monohydrate), for preparing a meloxicam tablet. Aqueous solubility of meloxicam in presence of β-CD was investigated. The tablets were prepared by direct compression and wet granulation techniques. The powder blends and the granules were evaluated for angle of repose, bulk density, compressibility index, total porosity, and drug content. The tablets were subjected to thickness, diameter, weight variation test, drug content, hardness, friability, disintegration time, and in vitro dissolution studies. The effect of β-CD on the bioavailability of meloxicam was also investigated in human volunteers using a balanced 2-way crossover study. Phase-solubility studies indicated an A_L-type diagram with inclusion complex of 1∶1 molar ratio. The powder blends and granules of all formulations showed satisfactory flow properties, compressibility, and drug content. All tablet formations prepared by direct compression or wet granulation showed acceptable mechanical properties. The dissolution rate of meloxicam was significantly enhanced by inclusion of β-CD in the formulations up to 30%. The mean pharmacokinetic parameters (C_max, K_e, and area under the curve [AUC]_0−∞) were significantly increased in presence of β-CD. These results suggest that β-CD would facilitate the preparation of meloxicam tablets with acceptable mechanical properties using the direct compression technique as there is no important difference between tablets prepared by direct compression and those prepared by wet granulation. Also, β-CD is particularly useful for improving the oral bioavailablity of meloxicam.     

Tablet formulation containing meloxicam and beta-cyclodextrin: mechanical characterization and bioavailability evaluation

The purpose of this research was to evaluate beta-cyclodextrin (beta-CD) as a vehicle, either singly or in blends with lactose (spray-dried or monohydrate), for preparing a meloxicam tablet. Aqueous solubility of meloxicam in presence of beta-CD was investigated. The tablets were prepared by direct compression and wet granulation techniques. The powder blends and the granules were evaluated for angle of repose, bulk density, compressibility index, total porosity, and drug content. The tablets were subjected to thickness, diameter, weight variation test, drug content, hardness, friability, disintegration time, and in vitro dissolution studies. The effect of beta-CD on the bioavailability of meloxicam was also investigated in human volunteers using a balanced 2-way crossover study. Phase-solubility studies indicated an A(L)-type diagram with inclusion complex of 1:1 molar ratio. The powder blends and granules of all formulations showed satisfactory flow properties, compressibility, and drug content. All tablet formulations prepared by direct compression or wet granulation showed acceptable mechanical properties. The dissolution rate of meloxicam was significantly enhanced by inclusion of beta-CD in the formulations up to 30%. The mean pharmacokinetic parameters (C(max), K(e), and area under the curve [AUC](0-infinity)) were significantly increased in presence of beta-CD. These results suggest that beta-CD would facilitate the preparation of meloxicam tablets with acceptable mechanical properties using the direct compression technique as there is no important difference between tablets prepared by direct compression and those prepared by wet granulation. Also, beta-CD is particularly useful for improving the oral bioavailablity of meloxicam.     

Effect of cadmium and zinc ethanolamine complexes on rat brain monoamine oxidase-B activity in vitro

Monoamine oxidase-B (MAO-B) from rat brain was inhibited strongly by the prepared cadmium and zinc ethanolamine complexes obtained from their sulphate and chloride salts. The inhibition of MAO-B by these complexes was time-dependent and fully reversible after dilution and sedimentation. In vitro, the cadmium ethanolamine complexes were more potent at inhibiting MAO-B than the zinc complexes. The inhibitory effect of these complexes follow the order: TEA>DEA>MEA, due to the alkyl residues and steric effect properties. The inhibition of MAO-B by cadmium and zinc ethanolamine complexes was a noncompetitive type. The K(i) values were calculated. The influence of the complexes on the activity of MAO-B was rather evaluated. It decreased the MAO-B activity. The IC(50) values of the two potent cadmium and zinc triethanolamine complexes on MAO-B were evaluated indicating that the complexes were tightly binding, but reversible inhibitors for MAO-B. In general, these systems may be used for preventing some neurodegenerative diseases.     

Fine and coarse regulation of reactive oxygen species in the salt tolerant mutants of barnyard grass and their wild-type parents under salt stress

The growth of the wild-type and three salt tolerant mutants of barnyard grass ( Echinochloa crusgalli L.) under salt stress was investigated in relation to oxidative stress and activities of the antioxidant enzymes superoxide dismutase (SOD: EC 1.15.1.1), catalase (CAT: EC 1.11.1.6), phenol peroxidase (POD: EC 1.11.1.7), glutathione reductase (GR: EC 1.8.1.7) and ascorbate peroxidase (APX: EC 1.11.1.1). The three mutants ( fows B17, B19 and B21) grew significantly better than the wild-type under salt stress (200 m M NaCl) but some salt sensitive individuals were still detectable in the populations of the mutants though in smaller numbers compared with the wild-type. The salt sensitive plants had slower growth rates, higher rates of lipid peroxidation and higher levels of reactive oxygen species (ROS) in their leaves compared with the more tolerant plants from the same genotype. These sensitivity responses were maximized when the plants were grown under high light intensity suggesting that the chloroplast could be a main source of ROS under salt stress. However, the salt sensitivity did not correlate with reduced K ⁺/Na ⁺ ratios or enhanced Na ⁺ uptake indicating that the sensitivity responses may be mainly because of accumulation of ROS rather than ion toxicity. SOD activities did not correlate to salt tolerance. Salt stress resulted in up to 10-fold increase in CAT activity in the sensitive plants but lower activities were found in the tolerant ones. In contrast, the activities of POD, APX and GR were down regulated in the sensitive plants compared with the tolerant ones. A correlation between plant growth, accumulation of ROS and differential modulation of antioxidant enzymes is discussed. We conclude that loss of activities of POD, APX and GR causes loss of fine regulation of ROS levels and hence the plants experience oxidative stress although they have high CAT activities.