carboxylase Biochem Pharmacol. 53 67 – 74 .
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Authors:N. Balogh, F. Krausz, P. Lévai, and et al.
, 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
Authors:Irena Baranowska, Piotr Markowski, Andrzej Wilczek, Magdalena Szostek, and Marlena Stadniczuk
Simple, rapid and selective NP-TLC and RP-TLC methods are described for analysis of l
-arginine, its primary metabolites (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 (
) on silica gel and 5% acetic acid-methanol-acetonitrile 50:35:15 (
) on RP-18 — and for separation of the drugs — acetonitrile-water 2:3 (
) on silica gel. The effects on selectivity of the polar modifier of mobile phases were also studied.
Authors:P. K. Gupta, V. V. Kuber, V. K. Ghosh, S. G. Bhope, V. Sharma, and S. Purohit
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 r2 = 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.
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 (Km) for arginine and maximum velocity (Vm) 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 (KP), 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 Km 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.
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%).
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.