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= 0.334±0.006 and 0.263±0.002 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 (18.5±4.83 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 ≤ 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.Â

Effet de quelques flavonoïdes sur une pénicillinase de Bacillus cereus

L’effet inhibiteur de certains flavonoïdes sur l’activité d’une β-lactamase d’une souche de Bacillus cereus a été testé et la relation structure-fonction a été établie. L’activité de La β-lactamase est déterminée en présence de différentes concentrations de la pénicilline G; le Km est de 106,3256 ± 32,0861 µM et la Vmax est de 0,6836 ± 0.00974 µM/min. Ces résultats reflètent une affinité de l’enzyme sur la pénicilline G. Six molécules de flavonoïdes ont été testées pour leur capacité à inhiber la b-lactamase. Le type d’inhibition et les constantes d’inhibition (Ki) ont été déterminés à une concentration de 150 µM. Parmi les molécules testées, l’épicatéchine et la naringine sont des inhibiteurs incompétitifs. La catéchine, la morine et la rutine sont des inhibiteurs compétitifs. La naringénine ne présente aucun effet inhibiteur. Les flavonoïdes ont une fonction 4-oxo semblable à celle de l’acide clavulanique et la pénicilline G. Il semble que le type du cycle, la position de OH et la présence d’un sucre dans les structures des molécules ont une importance majeure

L’impact du contexte urbain et environnemental sur le rafraichissement de la température en ÉTÉ : cas du grand ensemble de Diar El Mahçoul à Alger

Dans le cadre d’une recherche doctorale sur la perception des ambiances urbaines dans le quartier Diar El Mahçoul, conçu par Fernand Pouillon, nous avons relevé au cours de notre travail de terrain la satisfaction des habitants quand au confort d’été dans les espaces extérieurs. Les recherches sur les problématiques des ambiances ont démontré que dans les milieux urbains les ambiances microclimatiques sont modifiées par l’influence de plusieurs paramètres aussi bien naturels qu’urbains et architecturaux. Compte tenu de la situation géographique de ce quartier, sur les hauteurs d’Alger, à proximité de la mer méditerranée et des masses végétales ainsi de sa morphologie de type grand ensemble, nous avons supposé l’influence de ces paramètres sur la température d’été. Afin de valider notre hypothèse, nous avons effectué des mesures microclimatiques dans la « Cité Confort Normal ». Suite à cela, nous avons fait une comparaison des paramètres microclimatiques collectées avec celles enregistrées par la station météo d’Alger. Les résultats ont conclu à des modifications climatiques particulièrement liées aux contextes urbain et environnemental et ont confirmé que durant la saison d’été, les températures dans la cité sont effectivement plus basses.   Mots clES: Alger, grand ensemble, Diar El Mahçoul, Fernand Pouillon, ambiances urbaines, microclimat urbain.   ABSTRACT Diar El Mahçoul neighbourhood, designed by F. Pouillon in Algiers, was the subject of several written typomorphologique evoking the quality of its architecture. However, no study has approached this area because of its ambiantale dimension. This paper is a part of a doctoral research on the urban environments perception in this housing district where we identified an inhabitant's satisfaction about summer comfort in outdoor spaces during our fieldwork. We supposed that this district location on Algiers heights near the Mediterranean Sea and the large vegetation surfaces around influence summer temperature. In order to validate our assumption, we took microclimatic measures in "Cité Confort Normal" and we made a comparison measures recorded by Algiers weather station (ONM). Results concluded that climate changes related to urban and environmental contexts is confirmed; particularly during the summer, temperatures in the city are lower. Keywords: Algiers, large housing estates, Diar El Mahçoul, Fernand Pouillon, urban microclimate

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