Conversion Of Salicylic Acid Research Articles

Hydroxyl radical generation in β-thalassemic red blood cells

To provide more experimental evidence for the proposed role of oxygen free radicals in red blood cell (RBC) damage in β-thalassemia, hydroxyl radical generation was studied in thalassemic (Th) vs. normal (N) RBC. ḃOH fluxes were quantified by the conversion of salicylic acid (SA) into its hydroxylated products, 2,3- and 2,5-dihydroxybenzoic acids (DHBA) and catechol, assayed with HPLC coupled to electrochemical detection. No significant difference in spontaneous ḃOH generation between N-RBC and Th-RBC was found. Ascorbic acid (0.5–3.0 mM) induced many-fold increases in SA hydroxylation in a dose-dependant manner in both types of cells. In the presence of ascorbate (1.0 mM), the SA hydroxylated products were determined in Th-RBC vs. N-RBC as follows (nmol/ml): 2,5-DHBA, 1.45 ± 0.06 vs. 1.81 ± 0.05 ( p = 0.001); 2,3-DHBA, 1.89 ± 0.21 vs. 1.15 ± 0.08 ( p = 0.008) and catechol, 0.87 ± 0.13 vs. 0.38 ± 0.05 ( p = 0.006). The results showed significant increase in the total SA hydroxylation in Th-RBC as compared to N-RBC with a tendency to form 2,3-DHBA and catechol at the expanse of 2,5-DHBA. The excessive ·OH generation in Th-RBC is attributed to the abnormally high content of redox active iron in the cytosolic and/or membrane compartments of these cells.

Reduction of Salicylic Acid to Salicylaldehyde with Modulated Alternating Voltage

The effect of superimposing sinusoidal, triangular, and square‐wave alternating voltage (aV) on the potentiostatic reduction of salicylic acid to salicylaldehyde has been studied. Polarization curves with aV modulation were measured with an amalgamated copper rotating disk electrode. Enhanced dc current densities were observed with increasing magnitude of superimposed aV. However, aV frequency and type did not have significant effect on the resulting dc current densities. Batch cell electrolysis experiments were conducted with a H‐type cell. The conversion of salicylic acid and yield of salicylaldehyde were measured as functions of electrolysis time, aV magnitude, type, and frequency. The superimposed aV significantly enhanced the reaction rate, conversion of salicylic acid, and the yield of salicylaldehyde. The energy consumption of ac electrolysis was higher than that of dc electrolysis.

Salicyl phenolic glucuronide pharmacokinetics in patients with rheumatoid arthritis.

The pharmacokinetics of salicyl phenolic glucuronide (SPG) and other salicylic acid (SA) metabolites were studied at three aspirin dosage regimens in eight patients with rheumatoid arthritis. Each patient received 1, 2 and 4 g enteric coated aspirin (ASA) daily in ascending order. At the end of each 2-week dosage period, plasma and urine were collected over a dosage interval for the estimation of various pharmacokinetic parameters. With increasing ASA dosage, mean clearance of SA to SPG was approximately constant (1.8 +/- 0.3, 1.7 +/- 0.2, and 1.5 +/- 0.2 ml/min at 1, 2 and 4 g/day, respectively) when related to plasma concentrations of total SA. The percentage of the ASA dosage recovered in urine as SPG increased from 5.2 +/- 1.1 to 7.1 +/- 1.1 to 10.5 +/- 1.7 at 1, 2 and 4 g/day, respectively. It was concluded, however, that the conversion of SA to SPG is saturable, since the mean clearance of SA to SPG decreased when calculated with respect to the plasma concentration of unbound SA (13.4 +/- 1.6, 11.0 +/- 1.4, and 6.6 +/- 1.9 ml/min at 1, 2 and 4 g/day, respectively). The kinetics of the formation and excretion of salicylurate and the excretion of gentisate were similar to those found in previous studies.

Salicylate metabolite kinetics after several salicylates.

Single oral doses of aspirin (ASA, 1,500 mg), sodium salicylate (NaSA, 1,500 mg, 1,200 mg), and salicyluric acid (SUA, 500 mg) were given to five subjects. Serial plasma and urine samples were collected for 24 hr (plasma) and up to 48 hr (urine); salicylic acid (SA), SUA, and gentisic acid (GA) were measured by high-pressure liquid chromatography. The plasma concentration/time profiles for SUA after ASA and NaSA were fitted to the empirical equation CpSUA = A-Bt-Ce-alpha t -- (A-C)e-beta t. Michaelis constants (Vm and Km) for the conversion of SA to SUA were calculated from the equation (formula see text), where Cl is the renal clearance of SUA, ke is the rate constant of elimination of SUA, CpSA is the plasma concentration of salicylic acid. The term Cl (formula see text) is the estimated rate of formation of SUA from SA at any time (t). The calculated values (mean +/- SD) of Vm, Km, and Kmf (Km in terms of unbound SA) were 43.4 +/- 10.1 mg SA/hr, 14.3 +/- 3.4 mg SA/l plasma, and 0.75 +/- 0.15 mg unbound SA/l plasma. The Vm values were in accord with those reported, but the value for Km was considerably lower. Renal clearances of SUA and GA were 340 +/- 51 and 65 +/- 10 ml/min.

About the Conversion of Salicylic Acid into Zinc Salicylate in Ointments and Pastes Containing Both Zinc Oxide and Salicylic Acid

About the Conversion of Salicylic Acid into Zinc Salicylate in Ointments and Pastes Containing Both Zinc Oxide and Salicylic Acid