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carboxylase Biochem Pharmacol. 53 67 – 74 . [6]. R. Böger S. Bode-Böger J. Frölich 1996 The L-arginine — nitric oxide pathway: Role in atherosclerosis and therapeutic implications Atherosc. 127 1 – 11 . [7]. R. Böger S

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Boger, R. H. (2008) L-Arginine therapy in cardiovascular pathologies: beneficial or dangerous? Curr. Opin. Clin. Nutr. Metab. Care 11 , 55–61. Boger R. H. L-Arginine therapy in

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, M., Schleiffer, R., Gosse, F., Hasselmann, M. and Seiler, N. (1995) Beneficial effects of L-arginine on intestinal epithelial restitution after ischaemic damage in rats. Digestion 56 , 400-405. Beneficial effects of L-arginine

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Adams MR, Forsyth CJ, Jessup W, Robinson J, Celermajer DS: Oral L-arginine inhibits platelet aggregation but does not enhance endothelium-dependent dilation in healthy young men. J. Am. Coll. Cardiol. 26, 1054

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Simple, rapid and selective NP-TLC and RP-TLC methods are described for analysis of l -arginine, its primary metabolites (l -citrulline, l -glutamine, l -ornithine, asymmetric N G , N G -dimethyl-l -arginine, symmetric N G , N G ′-dimethyl-l -arginine, N G -nitro-l -arginine, N G -hydroxy-l -arginine, N G -monomethyl-l -arginine, agmatine, putrescine, spermidine, spermine, and creatine) and selected drugs (dexamethasone, prednisolone, furosemide, vancomycin, amikacin, fluconazole, digoxin, captopril, dipyrone, metoprolol, and sildenafil), in different therapeutic groups, in model solutions and in spiked human urine. NP-TLC and RP-TLC methods have been used to study the retention of the substances. A variety of mobile phase systems were evaluated for separation of ARG and its metabolites — methanol-50% acetic acid 3:1 ( v/v ) on silica gel and 5% acetic acid-methanol-acetonitrile 50:35:15 ( v/v ) on RP-18 — and for separation of the drugs — acetonitrile-water 2:3 ( v/v ) on silica gel. The effects on selectivity of the polar modifier of mobile phases were also studied.

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Summary

A simple, rapid, and specific thin layer chromatographic (TLC) method has been developed and validated for the simultaneous estimation of icariin and l-arginine from commercial polyherbal formulations for sexual dysfunction. The separation of the methanol extract of these formulations was achieved on silica gel 60 F254 aluminum backed TLC plates by using ethyl acetate-acetone-glacial acetic acid-formic acid-water 12:2:1:2:2 (υ/υ) as mobile phase. Densitometric analysis of icariin and l-arginine was monitored in absorbance mode at 270 and 195 nm, respectively. The linear regression analysis data for the calibration plots for icariin and l-arginine showed good linear relationship with r 2 = 0.9984 +- 0.01 and 0.9968 +- 0.02, in the concentration ranges of 250–750 and 500–1500 ng/spot, respectively. The method was validated for precision, robustness, and recovery. The average percentage recovery was found to be 98.26% for icariin and 99.63% for l-arginine. The limits of detection and quantitation were 72, 116 and 238, 383 ng/spot, respectively, for icariin and l-arginine. Statistical analysis proves that the method is repeatable and selective for the estimation of the targeted drugs. Since the proposed mobile phase effectively resolves the icariin and l-arginine, this method can be applied for the identification and quantitation of these components in herbal extracts and marketed formulations.

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Abstract  

A new thermokinetic reduced extent method for the product inhibition of single substrate enzyme-catalyzed reactions is proposed and compared with the traditional initial rate method in this paper. The arginase-catalyzed hydrolysis of L-arginine to L-ornithine and urea was studied at 37C in 40 mM sodium barbiturate-HCl buffer solution (pH=9.4). Michaelis constant (K m) for arginine and maximum velocity (V m) of the reaction were determined by initial method and thermokinetic method. The activation of exogenous manganese to this reaction was also studied. The product inhibition constant (K P), which cannot be obtained directly from the initial rate method, was determined by thermokinetic without adding L-ornithine to the reaction system. When the concentration of Mn2+ in cell is 0.1 mM, the enzyme gets its full activity. Incubation arginase with appropriate concentration of Mn2+resulted in increased Vmax and a higher sensitivity of the enzyme to product with no change in the K m for arginine. We suggest that the exogenous manganese ions in solution have just recovered the activity of arginase, which was lost in dissolving and dilution, but no effect on the mechanism of the reaction.

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Abstract  

A simple and efficient column chromatographic method has been developed for the sequential separation of U(VI), Th(IV) and Ce(III) using poly[dibenzo-18-crown-6] as stationary phase and l-arginine as a counter ion. The different elution patterns with various eluting agents were observed for individual element. The capacity of poly[dibenzo-18-crown-6] for U(VI), Th(IV) and for Ce(III) was found to be 0.96, 0.86 and 1.49 (±0.01) mmol/g of crown polymer, respectively. The method is efficient to separate the elements in multicomponent mixtures and has good recovery. The method is extended to determine the U(VI), Th(IV) and Ce(III) from monazite sand. The method is simple, rapid and selective having good reproducibility (~±2%).

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Acta Physiologica Hungarica
Authors: Z Oreščanin, Z Oreščanin, Z Oreščanin, SR Milovanović, SR Milovanović, and SR Milovanović

In the present study we investigated the mechanism of nitric oxide induced relaxation of renal arteries, with or without endothelium, taken from normotensive and spontaneously hypertensive (SH) rats. With this purpose in mind, the effects of the nitric oxide donor, sodium nitroprusside (SNP), with and without L-arg in the medium, on isolated rat renal artery relaxation were studied. Relaxing effect of SNP was higher in normotensive (10-5 M of SNP caused 220% of relaxation in the cases with endothelium and 240% without endothelium), in comparison with SH rats (100% of relaxation with endothelium and 150% without). L-arg antagonized the relaxing effect of SNP in the examined renal arteries, more in normotensive (100-160% with endothelium and 110-195% without) than in hypertensive ones (0-10% with endothelium and 35-75% without) at SNP concentrations 10-7-10-5 M, respectively (*P<0.05; **P<0.001). L-arg did not significantly change relaxing effect of SNP in the isolated renal arteries with endothelium taken from SH rats, which show that L-arg, by modifying the chemical versatility of NO into redox active forms -nitrosonium (NO+) and -nitroxyl (NO-), produces different relaxing effects in normotensive and hypertensive isolated arteries of rats, with or without endothelium, potentiating the role of nitroxyl induced relaxation in SH rats.

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