25 research outputs found
INHIBITORY EFFECTS OF ANCHUSA AZUREA EXTRACTS ON XANTHINE OXIDASE ACTIVITY AND ITS HYPOURICEMIC EFFECTS ON MICE
Objective: The aim of the present study was to determine the effects of the polyphenols and flavonoids from Anchusa azurea on XO activities in vitro and on serum and liver uric acid levels in normal and potassium oxonate-induced hyper uricemic mice. In addition, the renal function of the mice after flavonoid administration was estimated by the determination of blood urea and creatinine analysis.Methods: In the present study, Anchusa azurea were extracted with solvent of varying polarity allowed its separation into four subfractions: crude extract (Cr) chloroform extract (ChE), ethyl acetate extract (AcE), and aqueous extracts (AqE). Total polyphenol and flavonoids contents of Anchusa azurea extracts were determined. The inhibitory activity of the extracts on the XO was evaluated and the type of inhibition was determined. Hyperuricemia is induced by intraperitoneally injection of potassium oxonate, the uric acid, urea and creatinine were measured in serum and supernatant of the liver. The effect of the extracts on renal function was evaluated. The rate of urea and creatinine levels can be indicators for the assessment of renal function.Results: AcE were the richest in polyphenols and ChE was the richest fraction in flavonoids. The inhibitory activity of the extracts on the XO was evaluated, the results obtained showed that the inhibition is dose-dependent and ChE and AcE have the best inhibitory effect (IC50= 0.334ñ0.006 and 0.263ñ0.002 mg/ml, respectively), and both showed a noncompetitive type of inhibition. For antihyperuricemic effect, AqE and CrE caused a decrease in serum uric acid (a decrease of 66%) followed by ChE with a percentage of 29.22 %. The AcE keeps almost the same value of uric acid of "PO" group. For the supernatant, only CrE caused a significant decrease of liver uric acid (18.5ñ4.83 mg/l). This decrease can be explained by the significant inhibition of the XO by inhibition of the synthesis pathways of uric acid. Comparing the urea level of "OP" group (0.48 g/l), only extracts CrE-AA, AqE-AA (0.41g/l, 0.39 g/l) decreased the level of urea significantly (P Ăąâ°Â€ 0.05) to the normal values of urea (0.34 g/l), we can conclude that the rate of urea and creatinine after treatment with plant extracts are normal and that the results of this study indicate the absence of renal damage in miceConclusion: Anchusa azurea fractions have a strong inhibitory effect on xanthine oxidase and also have a significant lowering effect on serum and liver creatinine and urea levels in hyper uricemic mice.Ă
Effet de quelques flavonoïdes sur une pénicillinase de Bacillus cereus
Lâeffet inhibiteur de certains flavonoĂŻdes sur lâactivitĂ© dâune ÎČ-lactamase dâune souche de Bacillus cereus a Ă©tĂ© testĂ© et la relation structure-fonction a Ă©tĂ© Ă©tablie. LâactivitĂ© de La ÎČ-lactamase est dĂ©terminĂ©e en prĂ©sence de diffĂ©rentes concentrations de la pĂ©nicilline G; le Km est de 106,3256 ± 32,0861 ”M et la Vmax est de 0,6836 ± 0.00974 ”M/min. Ces rĂ©sultats reflĂštent une affinitĂ© de lâenzyme sur la pĂ©nicilline G. Six molĂ©cules de flavonoĂŻdes ont Ă©tĂ© testĂ©es pour leur capacitĂ© Ă inhiber la b-lactamase. Le type dâinhibition et les constantes dâinhibition (Ki) ont Ă©tĂ© dĂ©terminĂ©s Ă une concentration de 150 ”M. Parmi les molĂ©cules testĂ©es, lâĂ©picatĂ©chine et la naringine sont des inhibiteurs incompĂ©titifs. La catĂ©chine, la morine et la rutine sont des inhibiteurs compĂ©titifs. La naringĂ©nine ne prĂ©sente aucun effet inhibiteur. Les flavonoĂŻdes ont une fonction 4-oxo semblable Ă celle de lâacide clavulanique et la pĂ©nicilline G. Il semble que le type du cycle, la position de OH et la prĂ©sence dâun sucre dans les structures des molĂ©cules ont une importance majeure
Gamma estimator of Jarzynski equality for recovering binding energies from noisy dynamic data sets
A fundamental problem in thermodynamics is the recovery of macroscopic equilibrated interaction energies from experimentally measured single-molecular interactions. The Jarzynski equality forms a theoretical basis in recovering the free energy difference between two states from exponentially averaged work performed to switch the states. In practice, the exponentially averaged work value is estimated as the mean of finite samples. Numerical simulations have shown that samples having thousands of measurements are not large enough for the mean to converge when the fluctuation of external work is above 4 kBT, which is easily observable in biomolecular interactions. We report the first example of a statistical gamma work distribution applied to single molecule pulling experiments. The Gibbs free energy of surface adsorption can be accurately evaluated even for a small sample size. The values obtained are comparable to those derived from multi-parametric surface plasmon resonance measurements and molecular dynamics simulations
Modified Douglas splitting methods for reactiondiffusion equations
We present modifications of the second-order Douglas stabilizing corrections method, which is a splitting method based on the implicit trapezoidal rule. Inclusion of an explicit term in a forward Euler way is straightforward, but this will lower the order of convergence. In the modifications considered here, explicit terms are included in a second-order fashion. For these modified methods, results on linear
stability and convergence are derived. Stability holds for important classes of reactionâdiffusion equations, and for such problems the modified Douglas methods are seen to be often more efficient than related methods from the literature.The work of A. ArrarĂĄs and L. Portero was partially supported by MINECO grant MTM2014-52859
Kinetics of Inhibition of Xanthine Oxidase by Lycium arabicum and its Protective Effect against Oxonate- Induced Hyperuricemia and Renal Dysfunction in Mice
Purpose: To evaluate the in-vitro inhibition of xanthine oxidase (purified from bovine milk) by extracts of Lycium arabicum, as well as it is in vivo hypouricemic and renal protective effects.Methods: Four extracts of Lycium arabicum, methanol (CrE), chloroform (ChE), ethyl acetate (EaE) and aqueous (AqE) extracts, were screened for their total phenolics and potential inhibitory effects on purified bovine milk xanthine oxidase (XO) activity by measuring the formation of uric acid or superoxide radical. The mode of inhibition was investigated and compared with the standard drugs, allopurinol, quercitin and catechin. To evaluate their hypouricemic effect, the extracts were administered to potassium oxonate-induced hyperuricemic mice at a dose of 50 mg/kg body weight.Results: The results showed that EaE had the highest content of phenolic compounds and was the most potent inhibitor of uric acid formation (IC50 = 0.017 ± 0.001 mg/mL) and formation of superoxide (IC50 = 0.035 ± 0.001 mg/ml). Lineweaver-Burk analysis showed that CrE and EaE inhibited XO competitively, whereas the inhibitory activities exerted by ChE and AqE were of a mixed type. Intraperetoneal injection of L. arabicum extracts (50 mg/kg) elicited hypouricemic actions in hyperuricemic mice. Hyperuricemic mice presented a serum uric acid concentration of 4.71 ± 0.29 mg/L but this was reduced to 1.78 ± 0.11 mg/L by EaE, which was the most potent hyporuricemic extract.Conclusion: L. arabicum fractions have a strong inhibitory effect on xanthine oxidase and and also have a significantly lowering effect on serum and liver creatinine and urea levels in hyperuricemic mice.Keywords: Lycium arabicum, Uric acid, Creatinine, Superoxide, Phenolic compounds, Flavonoids, Hyperuricemi
Olive oils from Algeria: Phenolic compounds, antioxidant and antibacterial activities
The phenolic compositions, antioxidant and antimicrobial activities against six bacteria of phenolic extracts of olive oil varieties from eleven Algerian varieties were investigated. The antioxidant activity was assessed by determining the scavenging effect on the DPPH and ABTS<sup>.+</sup> radicals. The antimicrobial activity was measured as a zone of inhibition and minimum inhibitory concentration (MIC) on human harmful and foodborne pathogens. The results show that total phenols was significantly (p < 0.05) correlated with DPPH (r = 0.72) and ABTS<sup>.+</sup> radicals (r = 0.76). Among the bacteria tested, <em>S. aureus</em> and to a lesser extent <em>B. subtilis</em> showed the highest sensitivity; the MIC varied from 0.6 to 1.6 mg·mL<sup>-1</sup> and 1.2 to 1.8 mg·mL<sup>-1</sup>, respectively. The results reveal that Algerian olive oils may constitute a good source of antioxidant and antimicrobial agents.<br><br>Se ha estudiado la composiciĂłn fenĂłlica y las actividades antioxidante y antimicrobiana, contra seis bacterias, de extractos de aceites de oliva de once variedades argelinas. La actividad antioxidante se evaluĂł mediante la determinaciĂłn del efecto captador de radicales de DPPH y ABTS<sup>.+</sup>. La actividad antimicrobiana se midiĂł como zona de inhibiciĂłn y como concentraciĂłn inhibitoria mĂnima (MIC) sobre bacterias perjudiciales humanas y agentes patĂłgenos transmitidos por los alimentos. Los resultados mostraron que los fenoles totales estĂĄ significativamente (p < 0,05) correlacionados con DPPH (r = 0,72) y los radicales ABTS<sup>.+</sup> (r= 0,76). Entre las bacterias ensayadas, <em>S. aureus</em> y, en menor grado <em>B. subtilis</em> mostraron la mayor sensibilidad; el MIC variĂł de 0,6 a 1,6 mg·mL<sup>-1</sup> y 1,2 a 1,8 mg·mL<sup>-1</sup> respectivamente. Los resultados muestran que los aceites de oliva argelinos pueden constituir una buena fuente de antioxidantes y agentes antimicrobianos
Migration of Naphthalene through Low Organic Content Sandy Soil Columns: Comparison of Unsaturated and Saturated Conditions
Improved Reweighting of Accelerated Molecular Dynamics Simulations for Free Energy Calculation
Accelerated
molecular dynamics (aMD) simulations greatly improve
the efficiency of conventional molecular dynamics (cMD) for sampling
biomolecular conformations, but they require proper reweighting for
free energy calculation. In this work, we systematically compare the
accuracy of different reweighting algorithms including the exponential
average, Maclaurin series, and cumulant expansion on three model systems:
alanine dipeptide, chignolin, and Trp-cage. Exponential average reweighting
can recover the original free energy profiles easily only when the
distribution of the boost potential is narrow (e.g., the range â€20<i>k</i><sub>B</sub>T) as found in dihedral-boost aMD simulation
of alanine dipeptide. In dual-boost aMD simulations of the studied
systems, exponential average generally leads to high energetic fluctuations,
largely due to the fact that the Boltzmann reweighting factors are
dominated by a very few high boost potential frames. In comparison,
reweighting based on Maclaurin series expansion (equivalent to cumulant
expansion on the first order) greatly suppresses the energetic noise
but often gives incorrect energy minimum positions and significant
errors at the energy barriers (âŒ2â3<i>k</i><sub>B</sub>T). Finally, reweighting using cumulant expansion to
the second order is able to recover the most accurate free energy
profiles within statistical errors of âŒ<i>k</i><sub>B</sub>T, particularly when the distribution of the boost potential
exhibits low anharmonicity (i.e., near-Gaussian distribution), and
should be of wide applicability. A toolkit of Python scripts for aMD
reweighting âPyReweightingâ is distributed free of charge
at http://mccammon.ucsd.edu/computing/amdReweighting/