Structural and hydration studies of waxy and mealy potato starch cultivars by deuterium,carbon-13 CP-MAS/MASS NMR,and electron microscopy

Proton and deuterium pulsed Nuclear Magnetic Resonance (NMR) techniques were employed to investigate the hydration properties of raw and cooked (steamed, oven baked and microwave baked) waxy (LaSoda and Pontiac) and mealy (Russet Burbank and Norchip) potato cultivars and starches. Three water components (T_2Q internal, T_2A medium and T_2B long component) were resolved in potato cultivars and starches. The first water component T_2Q is assigned to the anisotropically bound water within the potato starch granule structure. The T_2A corresponds to trapped water, whereas, the T_2B-long component is assigned to the average between weakly bound and free water populations. The anisotropically bound water (T_2Q internal) in potato cultivars and starches does not seem to be in fast chemical exchange with free and weakly bound water populations. Well defined powder patterns with a residual deuterium quadrupole splitting of about 1 kHz were observed at 22°C for raw potato cultivars and starches (17%, w/w). The quadrupole splitting, however, disappeared after cooking as a result of heat induced structural changes, and only rapidly, isotropically reorienting water remained. The T_2A and T_2B values were also significantly affected by the cooking method. The T_2B values of cooked potatoes were shorter than those of raw potatoes. Heat induced structural changes were reflected in the shorter T_2B value of the cooked and crushed potatoes. Lower average ¹H NMR transverse relaxation rates were observed in cooked waxy (LaSoda) in comparison with those of other potatoes.     

Development and validation of a ultraperformance liquid chromatography–tandem mass spectrometry method for quantifying free and total dabigatran in human plasma: An application for a bioequivalence study

Dabigatran etexilate mesylate (DABE), a prodrug, quickly changes into dabigatran (DAB) after its oral administration. Accordingly, detecting DABE in plasma is practically unmanageable. An ultraperformance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS) technique was developed and validated to compute free DAB in participants. For the first time, the central composite design, a type of response surface methodology, was applied for optimizing variables affecting the cleavage of glucuronide bond. In addition, the pharmacokinetic parameters of generic medication (okanadab) were determined, and the obtained outcomes were compared with those of the branded drug (pradaxa). The sample preparation was done using methanol as a protein precipitant and the separation was achieved using an ACQUITY UPLC BEH C₁₈ column (2.1 × 50 mm, 1.7 μm). The elution was isocratically conducted using 10 mM ammonium formate:methanol (72:28, v/v) as a mobile phase and the flow rate was 0.25 mL/min. Multiple reaction monitoring and positive electrospray ionization were used. The determination was performed within 1 min, and the calibration growth curve was established over a range of 1.19–475 ng/mL using DAB-d3 as a tagged internal standard. Bioequivalence research was validated following the US Food and Drug Administration (US FDA) guidelines for bioanalytical procedures and acceptable outcomes were achieved. The outcomes for okanadab and pradaxa did not differ significantly.     

Effects of aqueous extracts of Acacia albida stem bark on Wistar albino rats infected with Trypanosoma evansi

The effect of aqueous extract of Acacia albida stem bark was investigated in Wistar albino rats infected with Trypanosoma evansi. The extract showed highest reduction in parasitemia at the dose of 600 mg/kg body weight (bw). A dose of 300 mg/kg bw improved packed cell volume the most by 14.35%. The group treated with 150 and 600 mg/kg bw of the extract showed significant decrease (P < 0.05) in alanine transaminase and aspartate transaminase levels which were lower than those of the group treated with diminazene aceturate. The group treated with 150 mg/kg bw of the extract showed the least urea, albumin and protein level and lowest relative organ weight. There was a significant difference (P < 0.05) in the levels of catalase and Thiobarbituric acid reactive substances in liver and kidney of the animals in the infected-untreated group and the extracts-treated groups. The results of this study show that the extracts of A. albida have antitrypanosomal activity against T. evansi infection.     

Weak Allee effects and species coexistence

In this article, we study the population dynamics of a two-species discrete-time competition model where each species suffers from either predator saturation induced Allee effects and/or mate limitation induced Allee effects. We focus on the following two possible outcomes of the competition: 1. one species goes to extinction; 2. the system is permanent. Our results indicate that, even if one species’ intra-specific competition is less than its inter-specific competition, weak Allee effects induced by predation saturation can promote coexistence of the two competing species. This is supported by the outcome of two-species competition models without Allee effects. Also, we discuss our results and future work on multiple attractors in competition models with Allee effects.     

Determination of γ-hexachlorocyclohexane and its metabolites in biological samples from rat

We have determined γ-hexachlorocyclohexane (lindane) and its metabolites in urine, serum and feces samples from rats using HPLC-UV-Vis and confirmation of mass with matrix assisted laser desorption/ ionization-time of flight (MALDI-TOF) analysis. Samples were collected from rats treated orally with lindane (17.6 mg/kg; 1/5 of LD₅₀) or vehicle for 2 weeks. Lindane and metabolites were extracted from samples with hexane and analyzed. The HPLC–MALDI-TOF is highly sensitive to the point of detecting very low level (5 ppm) of lindane and metabolites. The HPLC-UV-Vis analysis confirmed the presence of lindane in urine (386–1652 ppm), serum (207–371 ppm) and feces (5–74 ppm). Control samples had no peak corresponding to lindane. MALDI-TOF analysis of urine and serum samples showed a major peak at 293 m/z, whereas feces showed a minor peak at 292–293 m/z, which were consistent with the peak obtained for standard lindane (293 m/z). Our data indicates that HPLC-UV-Vis–MALDI-TOF combo method is sensitive for detecting and quantifying lindane and its metabolites in serum, urine and feces. Our results further showed that minor quantities of lindane and metabolites were excreted through feces confirming that the main pathway for excretion of lindane and metabolites is through urine.     

A selective and efficient chemosensor for the rapid detection of arsenic ions in aqueous medium

Research on Chemical Intermediates - The development of selective, efficient, and economical sensors for the rapid determination of arsenic in an aqueous medium is of paramount importance, due to...     

Ligand and Structure-Based In Silico Determination of the Most Promising SARS-CoV-2 nsp16-nsp10 2′-o-Methyltransferase Complex Inhibitors among 3009 FDA Approved Drugs

As a continuation of our earlier work against SARS-CoV-2, seven FDA-approved drugs were designated as the best SARS-CoV-2 nsp16-nsp10 2′-o-methyltransferase (2′OMTase) inhibitors through 3009 compounds. The in silico inhibitory potential of the examined compounds against SARS-CoV-2 nsp16-nsp10 2′-o-methyltransferase (PDB ID: (6W4H) was conducted through a multi-step screening approach. At the beginning, molecular fingerprints experiment with SAM (S-Adenosylmethionine), the co-crystallized ligand of the targeted enzyme, unveiled the resemblance of 147 drugs. Then, a structural similarity experiment recommended 26 compounds. Therefore, the 26 compounds were docked against 2′OMTase to reveal the potential inhibitory effect of seven promising compounds (Protirelin, (1187), Calcium folinate (1913), Raltegravir (1995), Regadenoson (2176), Ertapenem (2396), Methylergometrine (2532), and Thiamine pyrophosphate hydrochloride (2612)). Out of the docked ligands, Ertapenem (2396) showed an ideal binding mode like that of the co-crystallized ligand (SAM). It occupied all sub-pockets of the active site and bound the crucial amino acids. Accordingly, some MD simulation experiments (RMSD, RMSF, R_g, SASA, and H-bonding) have been conducted for the 2′OMTase—Ertapenem complex over 100 ns. The performed MD experiments verified the correct binding mode of Ertapenem against 2′OMTase exhibiting low energy and optimal dynamics. Finally, MM-PBSA studies indicated that Ertapenem bonded advantageously to the targeted protein with a free energy value of −43 KJ/mol. Furthermore, the binding free energy analysis revealed the essential amino acids of 2′OMTase that served positively to the binding. The achieved results bring hope to find a treatment for COVID-19 via in vitro and in vivo studies for the pointed compounds.     

Multicomponent synthesis of novel thiazolo[3,2-a]pyridin-8-yl-phosphonates as a model of plant growth regulator

A series of thiazolo[3,2-a]pyridin-8-yl-phosphonate derivatives have been obtained by the reaction of diethyl (E)-((4-oxothiazolidin-2-ylidene)methyl)phospohonate, malononitrile and two equivalent of various aromatic aldehydes in a multicomponent reaction with good yields. The structures of the new compounds are confirmed by spectroscopic methods (IR, ¹H, ¹³C, ³¹P NMR and HRMS). Compound diethyl-(Z)-(5-amino-6-cyano-2-(4-nitrobenzylidene)-7-(4-nitrophenyl)-3-oxo-3,7-dihydro-2H-thiazolo[3,2-a]pyridin -8-yl)phosphonate (4k) at 1?mM concentration enhanced biomass plant height, number of branches and leaf area of tomato plants of at least two-fold compared to the control plants. In common bean plants, this compound enhanced the chlorophyl content and delayed senescence in comparison to the control plants. Therefore, in future studies, the compound(s) would be further tested to evaluate deeply their mode of action at physiological, biochemical and molecular level to finally enhance crop productivity of various plants.     

Common fixed points Noor iteration for a finite family of asymptotically quasi-nonexpansive mappings in Banach spaces

In this paper, we introduce a general iteration scheme for a finite family of asymptotically quasi-nonexpansive mappings. The new iterative scheme includes the modified Mann and Ishikawa iterations, three-step iterative scheme of Xu and Noor and Khan and Takahashi scheme as special cases. Our results are generalizations as well as refinement of several known results in the current literature.