Hanna Hopkała

Changes in antioxidant status of lung tissue in experimental diabetes in rabbits

OBJECTIVES Hyperglycaemia can result in oxidative stress which may affected as cellular tissue damage. DESIGN AND METHODS After 3, 6, 12 and 24 weeks of hyperglycaemia oxidative stress related parameters were measured in lung tissue of diabetic and control rabbits. RESULTS Decreased activities of antioxidative compounds and intensification of lipid peroxidation process were found in diabetic lung. CONCLUSIONS The data obtained suggest that hyperglycaemia induces oxidative stress in lung tissue which may play an important role in pathogenesis of diabetic complications.

Reversed‐Phase Thin‐Layer Chromatography of Three New Oral Antidiabetics and Densitometric Determination of Pioglitazone

Abstract The thin‐layer chromatographic behavior of new oral antidiabetic drugs, pioglitazone, rosiglitazone, and repaglinide has been investigated. For reversed‐phase (RP) chromatography, chemically bonded cyanopropyl plates with mobile phases comprising 1,4‐dioxane with phosphate buffers were used. The influence of the pH on the separation of the drugs was also examined. Then, a simple, rapid, and stability‐indicating high performance thin‐layer chromatographic method has been developed and validated for the quantitative determination of pioglitazone in tablets. Analysis was performed with 1,4‐dioxane–phosphate buffer of pH 4.4 (5:5) as the mobile phase. Detection and quantification were performed by classical densitometry at the wavelength of maximum absorption of pioglitazone, 266 nm. A calibration plot was constructed in the range of 0.4–2.4 µg/10 µL and was linear with a good correlation coefficient (r = 0.9957). Precision was validated by replicate analyses of standard solutions, and accuracy by analysis of fortified samples. The precision of the proposed chromatographic method expressed as mean relative standard deviation (RSD) was 4.99% and 2.57%, respectively, for the lowest and the highest calibration levels. Recovery from the fortified samples ranged from 98.09% to 103.28%. The mean (±SD) recovery from tablets was 99.79% ± 1.57%.

Differences in antioxidant status in skeletal muscle tissue in experimental diabetes.

BACKGROUND It has been suggested that oxidative stress may play an important role in pathogenesis of diabetic complications. The present study was designed to evaluate the oxidative stress-related parameters in alloxan (A)-induced long-term diabetes in rabbits. METHODS After 3, 6 and 12 weeks of diabetes, activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), glutathione reductase (GSSG-R) and concentrations of ascorbic acid (AA) and free sulfhydryl compounds (SH) were measured in skeletal muscle of diabetic rabbits and the normal control subjects. The products of lipid peroxidation (MDA) were also estimated. RESULTS In our tests, the muscle SOD activity, SH and AA concentrations were significantly reduced. CAT activity increased significantly at all time intervals. GSH-Px activity decreased after 3 weeks and then remained at the control level. GSSG-R activity decreased progressively at 3rd and 6th week and then significantly increased. MDA level increased initially, dropped below baseline after 6 weeks and then remained at the level of the control group. CONCLUSIONS The changes observed in the present experiment suggest a significant imbalance in antioxidative system in the skeletal muscle of rabbits with alloxan-induced diabetes. Such study may lead to therapeutic approaches for limiting the damage from oxidation reactions and preventing the diabetic complications.

Quantitative analysis of repaglinide in tablets by reversed-phase thin-layer chromatography with densitometric UV detection

A simple, rapid, and stability-indicating thin-layer chromatograph-ic method has been developed for quantitative determination of repaglinide in tablets. Analysis was performed on RP-8 TLC plates with acetonitrile—pH 6.0 phosphate buffer, 60 + 40 (% v/v), as mobile phase. Detection and quantification were performed by classical densitometry at the wavelength of maximum absorption of repaglinide, 225 nm. A calibration plot constructed in the range 0.6–3.6 µg/10 µL was linear with a good correlation coefficient (r = 0.998 ± 0.001, mean ± SD, n = 5). Limits of quantitation and detection of repaglinide were 0.27 µg/10 µL and 0.08 µg/10 µL, respectively. Instrumental precision established at three concentrations of the drug ranged from 3.92 to 0.97% for the lowest and highest concentrations of repaglinide, respectively. The mean intra-day and inter-day variability, including three concentrations of re-paglinide, were 1.93 and 2.25% (n = 9), respectively. Recovery from model mixtures, at three levels of addition, ranged from 103.06 to 102.49% for the lowest and highest levels, respectively. Total mean ± SD recovery was 102.71 ± 2.04% (n = 15). The mean ± SD recovery from commercially available tablets was 101.85 ± 1.83% (n = 10). The effect of pH, temperature, and UV light on degradation of repaglinide was also investigated. The analytical method presented was found to be simple, reliable, and convenient for routine pharmaceutical analysis. Its analytical performance fulfilled acceptance criteria established for TLC methods in the official literature.

TLC Analysis of Non-Steroidal Anti-Inflammatory Drugs and Videodensitometric Determination of Fenbufen in Tablets

The chromatographic separation of fenbufen, ibuprofen, ketoprofen, diclofenac sodium, mefenamic acid, and tiaprofenic acid has been investigated. Normal-phase chromatography on silica gel by the ascending and horizontal techniques, and reversed-phase chromatography on octadecyl-bonded silica gel (RP-18) in horizontal chambers, were performed with suitable mobile phases. The substances were identified by UV illumination at λ = 254 nm and by use of dyeing reagents. Reversed phase chromatography with phosphate buffer, pH 5.73-10% CTMA-Br in methanol, 3.5 + 6.5 (v/v), as mobile phase enabled better separation of the six drugs than normal-phase mode. A simple videodensitometric TLC method on silica gel RP-18 was developed and validated for quantitative determination of fenbufen in tablets. The limits of detection and quantification were determined by videodensitometry at λ = 254 nm. A calibration plot was constructed in the range 2.0-12.0 μg/5-μL spot and was linear with a good correlation coefficient (0.9926). RSD for quantitation of fenbufen were from 2.44 to 3.10%. The method was applied satisfactorily to pharmaceutical preparations.

Normal- and Reversed-Phase Thin-Layer Chromatography of Seven Oral Antidiabetic Agents

The chromatographic behavior of seven oral antidiabetic drugs -chlorpropamide, tolbutamide, glibenclamide, metformin, pioglitazone, rosiglitazone, and repaglinide - has been investigated. Normal-phase chromatography was performed on silica gel and alumina layers with mixtures of chloroform, diethyl ether, and ethyl acetate as mobile phases. For more effective resolution aqueous ammonia or acetic acid was added to the mobile phases. Silica gel enabled better separation than alumina. Reversed-phase chromatography was performed on octadecyl-bonded silica gel (RP-18) with mixtures of acetonitrile or 2-propanol with phosphate buffer as mobile phases. The effect of pH on the separation of the drugs was also examined. For separation of these drugs reversed-phase chromatography was more effective than use of normal-phase mode.

Rapid HPTLC Determination of Rosiglitazone in Pharmaceutical Formulations

Abstract A new, simple, rapid, and stability‐indicating high‐performance thin layer chromatographic (HPTLC) method has been developed and validated for the determination of rosiglitazone in tablets. Analysis was performed on silica gel 60F254 plates in horizontal chambers with chloroform–ethyl acetate–25% ammonium hydroxide (5:5:0.1, v/v) as mobile phase. Detection and quantification were performed by classical densitometry at 240 and 254 nm. The active substance was extracted from tablets with ethanol. Calibration plots were constructed in the range 0.2–1.0 µg/10 µL and were correlated with good correlation coefficients (r 240 = 0.9993; r 254 = 0.9994). Precision was validated by replicate analyses of standard solutions, and accuracy by analysis of fortified samples. The precision of the proposed chromatographic method, expressed as mean RSD was 3.58 and 2.76% for 240 nm, and 8.23 and 6.56% for 254 nm, for the lowest and the highest calibration levels, respectively. The mean recoveries from the fortified samples ranged from 89.48% to 99.38% for 240 nm, and from 89.05% to 100.89% for 254 nm. The mean recoveries from tablets were 101.95% and 103.2% for assays at 240 and 254 nm, respectively.

Interleukin-6 and oxidative stress in plasma of alloxan-induced diabetic rabbits after pioglitazone treatment.

There is evidence that oxidative stress might be implicated in promoting a state of systemic inflammation in diabetic patients. Understanding the role of reactive oxygen species in the inflammatory response in diabetes becomes essential in finding preventive treatments. Pioglitazone is a new oral antidiabetic agent with potent antioxidant and anti-inflammatory properties. The drug is a high affinity ligand of peroxisome proliferator-activated receptor gamma. This receptor seems to be involved in the control of inflammation by modulating the production of inflammatory mediators. In the present study, the changes in some markers of enhanced oxidative stress and in the level of pro-inflammatory interleukin-6 (IL-6) were examined in plasma of diabetic rabbits after 4 and 8 weeks of pioglitazone treatment. Ascorbic acid (AA) concentration and total antioxidant status (TAS) in plasma of diabetic animals were diminished and significantly elevated after pioglitazone treatment (p < 0.05). Protein carbonyl groups (PCG) content and IL-6 concentration were elevated in plasma of diabetic animals and significantly diminished after pioglitazone treatment. The results obtained in the present study confirm the relations of cytokine systems with oxidative stress in plasma of diabetic subjects. They also suggest the antioxidative and antinflammatory properties of pioglitazone.

Cyproheptadine ion-selective electrodes and their applications in some pharmaceutical formulations

Abstract Cyproheptadine hydrochloride (C) shows an antihistaminic as well as antimuscarine, antiserotonic and sedative activity. The present work describes sensitive and reasonably selective poly(vinyl chloride) membrane electrodes for Cyproheptadine. They are based on the use of cyproheptadine-tetrakis(4-chlorophenyl)borate (C-TC1PB) and cyproheptadine-dipicrylamine (C-DPA) as a novel electroactive compound. Cyproheptadine ion-selective poly(vinyl chloride) membrane electrodes contain an ion-pair complex of Cyproheptadine with 2-nitrophenyloctyl ether (ENPO), 2-nitrodiphenyl ether (ENdP), bis(2-ethylhexyl)sebacate (DOS) and l-isopropyl-4-nitrobenzene (IPNB) as solvent mediators. The performance of the electrodes was investigated by measuring the e.m.f. values of 10 −2 –10 −7 mol 1 −1 Cyproheptadine hydrochloride. The effect of pH on the potential readings of the Cyproheptadine electrodes was checked by the recording on the e.m.f. of 10 −3 mol 1 −1 Cyproheptadine hydrochloride with pH values from 2.5 to 7.0. Potentiometric selectivity coefficient were measured by the separate solution method using a 10 −3 mol 1 −1 concentration of Cyproheptadine and the some concentration of interferent cations. The electrode obtained with C-TC1PB with DOS and electrode with C-DPA with IpNB were used in the potentiometric determination of Cyproheptadine in bulk substance and tablets PERITOL 4 mg as indicator electrodes. The results are in good agreement with those obtained by UV spectrophotometric method. Keywords: Cyproheptadine hydrochloride; Ion-selective electrode; Potentiometric titration; Cyproheptadine determination; Drag analysis

Separation of fluoroquinolone antibiotics by TLC on silica gel, cellulose and silanized layers

Separation of the fluoroquinolone antibiotics has been examined using numerous mobile phases and commercially available TLC plates precoated with silica gel, cellulose, and chemically bonded silica gel (RP-C18). The best separation of the antibiotic standards was achieved on silica gel with methanol–acetone–1 mol L–1 citric acid–triethylamine, 2.8 + 2 + 0.2 + 0.5 (v/v) as mobile phase, on cellulose with dichloromethane–isopropanol–THF–25% ammonia, 4 + 6 + 3 + 3 (v/v), as mobile phase, and on silanized silica gel RP-C18 with methanol–0.07 mol L–1 phosphate buffer, pH 6–10 mmol L–1 benzyldimethyltetradecylammonium chloride, 6 + 3 + 1 (v/v), as mobile phase. The separated compounds were detected under UV irradiation at λ = 254 nm or by treatment of the plate surface with different dyeing agents.