Synthesis,Characterization, and Conformational Study of Acylhydrazones of α,β‐Unsaturated Aldehydes

New acylhydrazone derivatives 1–6 have been synthesized by condensation of tert‐butylphenoxyhydrazide and cinnamaldehyde A or β‐chloro‐α,β‐unsaturated aldehydes B–F . They were characterized by IR, (¹H, ¹³C, ¹⁹F) nuclear magnetic resonance (NMR), and high‐resolution mass spectroscopy. The NMR data show the existence of the cis/trans‐amide conformers due to N–C(O) bond rotation in addition to the E/Z isomers around the C=C bond of some of the starting aldehydes. The solvent polarity effects on the ratios of the cis/trans‐amide rotamers have also been investigated. Importantly, rotational barriers around the N–C(O) bond for all compounds 1–6 (62.9–68.8 kJ mol^–1) were calculated using the coalescence‐temperature method according to the Eyring equation. The results are discussed and compared with those previously reported for related acylhydrazones of aryl adehydes and acetone.     

In Vitro Alpha-Amylase and Alpha-Glucosidase Inhibitory Activity and In Vivo Antidiabetic Activity of Withania frutescens L. Foliar Extract

Withania frutescens L. is a wild perennial woody plant used by the local population for diverse therapeutic purposes. This work aims to study for the first time the potential inhibitory effect of this plant hydroethanolic extract on α-amylase and α-glucosidase activities using in vitro methods and its antidiabetic and antihyperglycemic activities using alloxan-induced diabetic mice as a model for experimental diabetes. Two doses were selected for the in vivo study (200 and 400 mg/kg) and glibenclamide, a well-known antidiabetic drug (positive control) in a subacute study (28 days) where the antihyperglycemic activity was also assessed over a period of 12 h on diabetic mice. The continuous treatment of diabetic mice with the extract of Withania frutescens for 4 weeks succeeded to slowly manage their high fasting blood glucose levels (after two weeks), while the antihyperglycemic test result revealed that the extract of this plant did not control hyperglycemia in the short term. No toxicity signs or death were noted for the groups treated with the plant extract, and it shows a protective effect on the liver and kidney. The in vitro assays demonstrated that the inhibition of alpha-amylase and alpha-glucosidase might be one of the mechanisms of action exhibited by the extract of this plant to control and prevent postprandial hyperglycemia. This work indicates that W. frutescens have an important long term antidiabetic effect that can be well established to treat diabetes.     

On Reflection with Two-Sided Jumps

Journal of Theoretical Probability - In the first part of this paper, we pose and solve a new version of Skorokhod problem with jumps, reflected in the half line $$mathbb {R}^{+}$$ and associated...     

Optimization of extraction process and characterization of water-soluble polysaccharide (Galactomannan) from Algerian biomass; Citrullus colocynthis seeds

In this work, the optimization of extraction of polysaccharides from Citrullus colocynthis curd polysaccharides (CCPs) is investigated by using the analysis of variance. For this aim, a chemical extraction method has been developed in order to be able to isolate CCPs at high level of purity. The extraction was performed by using boiling water at different extraction times (30, 60 and 120?min), extraction temperatures (50, 75 and 100°C), and a material ratio (30, 60 and 100?g/ml), for maximum polysaccharide extraction. The 3-D response surface plot and the contour plot derived from the mathematical models are used to determine the optimal conditions. The optimum extraction conditions are as follows: extraction temperature 100°C, extraction time 120?min and the ratio of water 30?ml/g. Under these conditions, the experimental final mass is 210.6?mg which is very close to the predicted value (209.46?mg) with a regression coefficient of 94.01%. In addition, the existence of the polysaccharide has been confirmed by the characterization of the galactomannan obtained from C. colocynthisis obtained by Fourier transform infrared-attenuated total reflection, IR-Raman spectroscopy and X-ray diffraction.     

Intraspecific variability of carbon isotope discrimination and its correlation with grain yield in safflower: prospects for selection in a Mediterranean climate

The goals of the present study were to obtain a first estimate of intraspecific variability of carbon isotope discrimination (Δ) in safflower, a thistle-like herbaceous plant, and to determine the statistical relationship between Δ and grain yield as well as its components in a collection of 45 accessions of different origins. Grain yield and aboveground biomass, harvest index, average grain weight, and Δ (measured on the bulk leaf organic matter) were investigated in experimental field conditions. A large variability was noted for all traits but a principal component analysis (PCA) allowed to identify several homogeneous groups of accessions. Average grain yield per plant varied between 1 and 39 g. Δ varied between 21.3 and 25.2?‰, i.e. a large variation of 3.9?‰. In our experiment, the variation of Δ was not significantly related to that of grain yield in the whole accession sample. However, we found contrasting trends for this relation within accession groups. These initial results motivate further experiments to assess more in depth correlation between Δ and yield in safflower and are encouraging regarding the possibility of using Δ as an effective selection index in safflower to obtain genotypes that efficiently consume water. This study also highlighted one accession that combines the two characters required in the Mediterranean regions, i.e. high yield performance and high water-use efficiency.     

Synthesis and amphiphilic properties of S-alkylthiopentonolactones and their pentitol derivatives

The amphiphilic properties of S-alkylthiopentono-1,4-lactones (D-ribono-, D-arabinono-, D-xylono-) and corresponding pentitol derivatives with the general formula Su-SR (R=CnH2n+1) are studied. It was shown that CMC, surface area, CPP, and pC20 are influenced by the following structural parameters: alkyl chain length, the number of free hydroxyls, cyclic or acyclic Su structure, and alditol configuration.     

A new indole alkaloid,antioxidant and antibacterial activities of crude extracts from Saccocalyx satureioides

Abstract

The new acylated indole alkaloid glucoside indole-3-carboxylic acid-(6'-O-caffeoyl)-β-D-glucoside 1 has been isolated from the ethyl acetate (EtOAC) extract of Saccocalyx satureioides Coss. & Dur. (Lamiaceae) together with eight known secondary metabolites 2-9. Two indoles 2 and 3, five methylated flavone aglycones 4-8 and one monoterpene glucoside 9 were reported for the first time in the genus Saccocalyx. The structural elucidation of these compounds was accomplished by spectroscopic methods including 1?D (¹H and ¹³C) and 2?D (COSY, HSQC and HMBC) NMR techniques, and mass spectrometry, and by comparison with literature data. Light petroleum, EtOAc, chloroform and n-butanol (n-BuOH) extracts of S. Satureioides were screened for their antioxidant activity using DPPH radical scavenging and β-carotene bleaching methods. The antibacterial activity of these extracts indicates that n-BuOH and EtOAc extracts possess the strongest activity.     

Measurement experimental set-up for thermal characterization of low thickness polymers

The characterization of the thermal properties of polymers represents a fundamental step in improving materials for energy harvesting processes. Thermal conductivity, for example, is measured by measuring heat flux and temperature difference. This study seeks to design and fabricate an experimental set-up to measure the thermal conductivity of low-thickness polymers at room temperature. It is unique in that it is an affordable and lightweight instrument developed using electrical resistance as a heater and a limited number of components. Error analysis and reproducibility analysis were carried out for the thermal conductivity. The instrument was found to be reliable in making thermal conductivity measurements with an average of ±7%.     

Phase Transition of Rubidium Lead Tetrathiophosphate RbPbPS4

The single crystal structure of RbPbPS₄ was determined at 293 K. The compound crystallizes in the orthorhombic space group Pnma (No. 62) with a = 17.486(1) Å, b = 6.7127(5) Å, c = 6.4191(5) Å, V = 753.5(1) ų, Z = 4. Differential scanning calorimetry shows a reversible structural phase transition at 182 K on cooling and at 184 K on heating. The phase transition is attributed to the displacement of the lead atoms which are located on the mirror planes at room temperature. In the low temperature modification, the Pb²⁺ ions are moved away from the mirror plane thus changing the coordination number from seven at low temperature to six at room temperature. The low temperature phase of RbPbPS₄ is non‐centrosymmetric with space group P2₁2₁2₁, which is a maximal translationengleiche subgroup index 2 (t2) of Pnma. The analysis demonstrates that the phase transition is of second order, or at least nearly so.