Assessment of vitamin B12 levels and cardiovascular risk factors in metformin- and non-metformin-treated type 2 diabetic patients.

Oxidative stress enhances cardiovascular risk. Metformin decreases intestinal absorption of vitamin B12. Our objective was the evaluation of type 2 diabetics focusing on differences due to their treatment. A prospective study on 224 type 2 diabetics was realized between 2015-2018 in Targu Mures, Romania, divided into 2 subgroups (metformin vs. other therapy - 2nd/3rd generation sulfonylureas, insulin, dietary regimen -, followed for at least one year) and non-diabetic controls (n=25) for oxidative stress level comparison. Serum homocysteine (HC), vitamin B12 were determined by chemiluminescence (Immulite One). Lipid peroxidation was assessed by serum malondialdehyde (MDA) measurement (HPLC). Biochemical tests, minerals, cystatin C, high-sensitivity C reactive protein (hs-CRP) were measured on Konelab20Xti, glycated hemoglobin on Nycocard Reader. GraphPad InStat-3 was used for statistics. Negative correlation occured between serum vitamin B12 and HC, this vitamin's level was significantly lower and serum zinc was significantly higher in patients on metformin. Hyperhomocysteinemia was present in 87% of the subjects, 46% had zinc deficiency and 41% elevated hs-CRP. Serum cystatin C showed positive correlation with creatinine. Serum MDA was significantly higher in diabetics compared to control patients. Elevated hs-CRP and homocysteine represent raised cardiovascular risk. Intense oxidative stress, vitamin, mineral deficiencies are frequent in diabetic subjects.

Profiling the Concentration of Reduced and Oxidized Glutathione in Rat Brain Using HPLC/DAD Chromatographic System.

This study aimed to develop a HPLC/DAD method in order to determine and quantify the reduced glutathione (GSH) and oxidized glutathione (GSSG) levels in rat brain. Due to the presence of the thiol group (-SH), GSH can interact with the Ellman's reagent (DTNB), with which it forms a reaction product through which the level of GSH can be quantified, using the DAD detection system. Chromatographic separation was achieved after a derivatization process by using a mobile phase acetonitrile (A) and phosphate buffer (20 mM, pH = 2.5) (B). The compounds of interest were detected at 330 nm using a chromatographic C8 column. The method of determination met the validation criteria, specified by the regulatory bodies. The applicability of the method was demonstrated in a chronic toxicology study of central nervous system (CNS), following different treatment regimens with haloperidol.

A Simple HPLC/DAD Method Validation for the Quantification of Malondialdehyde in Rodent's Brain.

In the present study, a HPLC/DAD method was set up to allow for the determination and quantification of malondialdehyde (MDA) in the brain of rodents (rats). Chromatographic separation was achieved on Supelcosil LC-18 (3 µm) SUPELCO Column 3.3 cm × 4.6 mm and Supelco Column Saver 0.5 µm filter by using a mobile phase acetonitrile (A) and phosphate buffer (20 mM, pH = 6) (B). Isocratic elution was 14% for (A) and 86% for (B). The injection volume (loop mode) was 100 µL with an analysis time of 1.5 min. Flow rate was set at 1 mL/min. The eluted compound was detected at 532 nm by a DAD detector by keeping the column oven at room temperature. The results indicated that the method has good linearity in the range of 0.2-20 µg/g. Both intra- and inter-day precision, expressed as RSD, were ≤15% and the accuracies ranged between ±15%. The lower limit of quantification (LLOQ), stability, and robustness were evaluated and satisfied the validation criteria. The method was successfully applied in a study of chronic toxicology following different treatment regimens with haloperidol and metformin.

Oxidative stress and peripartum outcomes (Review).

Pregnancy, labor and childbirth are accompanied by excessive oxidative aggression. The excessive formation of free radicals [reactive oxygen species (ROS), reactive nitrogen species (RNS), chlorine reactive species (CRS)] causes cellular oxidative damage, which can be scavenged by enzymatic or non-enzymatic antioxidants in normal healthy pregnancy, physiological labor and delivery without any complications. An imbalance between the pro-oxidant and antioxidant factors may lead to oxidative stress, which contributes to the development of many diseases. This oxidative aggression can be a precursor for pathologies in the pregnant woman including eclampsia, miscarriage, preterm labor, and intrauterine growth retardation; in the offspring it may lead to bronchopulmonary dysplasia/chronic lung disease, necrotizing enterocolitis, retinopathy of prematurity, and periventricular leukomalacia. This review summarizes the studies conducted to identify the mechanisms of oxidative stress and the effect of cell membrane oxidation, the mechanisms that are behind oxidative stress-related diseases, and also those studies which have demonstrated the effect of antioxidants in preventing diseases or diminishing the effects of oxidative stress in the body, in obstetrics and neonatology.

Efficacy of a commercial herbal formula in chicken experimental coccidiosis.

BACKGROUND: Coccidiosis represents a serious threat to the poultry industry, affecting production and causing high morbidity, mortality and significant costs resulting from treatment and prophylaxis. In-feed anticoccidials have been used for decades for managing avian coccidiosis and were very effective until drug resistance emerged. The use of natural remedies has become a promising alternative in combating coccidiosis in chickens. Therefore, the purpose of the present study was to assess the efficiency of a commercial herbal formula (H), as oral liquid preparations, in experimental chicken coccidiosis. METHODS: Two independent controlled battery experiments (BE1 and BE2) were designed and the product was tested in 3 different formulas (H1, H2 and H3): H1 contained a propylene glycol extract of Allium sativum and Thymus serpyllum; H2 contained Origanum vulgare, Satureja hortensis and Chelidonium majus; and H3 contained Allium sativum, Urtica dioica, Inula helenium, Glycyrrhiza glabra, Rosmarinus officinalis, Chelidonium majus, Thymus serpyllum, Tanacetum vulgare and Coriandrum sativum. Chickens were divided into five groups for each BE as follows: (i) uninfected untreated control (UU1, UU2); (ii) infected untreated control (IU1, IU2); (iii) infected treated with amprolium (ITA1, ITA2); and (iv, v) two experimental groups infected treated with H1 (ITH1) and H2 (ITH2) formulas in the BE1 and with H3 (ITH3-5 and ITH3-10) formula in the BE2. The chickens from infected groups were challenged with 5000 (BE1) and 50,000 (BE2) sporulated oocysts of Eimeria spp. (E. acervulina, E. tenella and E. maxima), respectively. The anticoccidial efficacy was assessed by recording the following: oocysts output (OPG), lesion score (LS), weight gain (WG), feed conversion ratio (FCR) and anticoccidial index (ACI). Additionally, polyphenolics and flavonoids (caffeic-chlorogenic acid, apigenin, kaempferol, luteolin, quercitin, quercitrin) from herb extracts found in H3 formula were determined by the liquid chromatography-tandem mass spectrometry (LC-MS/MS) method. RESULTS: H1 and H2 reduced the WG, and increased the FCR and OPG compared with controls. H1 reduced the duodenal lesions, whilst H2 reduced the caecal lesions, compared with control. H3 decreased the OPG of Eimeria spp., reduced the total lesion score and improved the zootechnical performance (weight gain and feed conversion ratio). According to ACI value, H1 and H2 had no efficacy on Eimeria spp. infection, but H3 had good to marked anticoccidial effect, the ACI being slightly greater in the group ITH3-5. According to the results of LC-MS/MS, the concentration of polyphenols in H3 formula was the highest, the sum of chlorogenic acid and caffeic acid being 914.9 µg/ml. CONCLUSIONS: H3 formula is a promising natural anticoccidial and field trials are recommended in order to validate the obtained data.

Extractability of polyphenols from black currant, red currant and gooseberry and their antioxidant activity.

In this study, we analyzed extracts of Ribes (black currant, red currant and gooseberry) fruits obtained with methanol, methanol 50% and water. For each extract total polyphenol content, total flavonoid content and total anthocyanin content was assessed. The antioxidant activity of extracts was evaluated by 1,1-Diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical scavenging capacity and by the photo-chemiluminescence (PCL) method. Identification and quantification of individual phenolic compounds was performed by means of high performance liquid chromatograph coupled with diode array detector (HPLC-DAD) analyses. From each fruit, best extraction of polyphenols was obtained with methanol 50%. In case of red currants and gooseberry there was no significant difference in flavonoids and anthocyanins extraction rate by the different extraction solvents. For black currants the methanol and methanol 50% extract presented the highest antioxidant activity. For red currants extracts with methanol 50% showed stronger antioxidant activity (IC50 = 5.71 mg/ml for DPPH, IC50 = 1.17 mg/ml for ABTS) than those with methanol or water. In case of gooseberry by the DPPH test the water extract proved to be the most active (IC50 = 5.9 mg/ml). In the PCL test black currants methanol 50% extract was over 6 times more powerful as the ones from red currants. In case of gooseberries, water extract presented the highest antioxidant activity (41.84 µmol AAE/g). In black currant cyanidin-3-glucoside was the major compound. Quercetin 3-O-glucoside was identified in each sample. From cinnamic acid derivatives neochlorogenic acid was present in black currants in the highest amount (356.33 µg/g).

Reversed phase HPLC for strontium ranelate: Method development and validation applying experimental design.

A reverse-phase HPLC (RP-HPLC) method was developed for strontium ranelate using a full factorial, screening experimental design. The analytical procedure was validated according to international guidelines for linearity, selectivity, sensitivity, accuracy and precision. A separate experimental design was used to demonstrate the robustness of the method. Strontium ranelate was eluted at 4.4 minutes and showed no interference with the excipients used in the formulation, at 321 nm. The method is linear in the range of 20-320 µg mL-1 (R2 = 0.99998). Recovery, tested in the range of 40-120 µg mL-1, was found to be 96.1-102.1 %. Intra-day and intermediate precision RSDs ranged from 1.0-1.4 and 1.2-1.4 %, resp. The limit of detection and limit of quantitation were 0.06 and 0.20 µg mL-1, resp. The proposed technique is fast, cost-effective, reliable and reproducible, and is proposed for the routine analysis of strontium ranelate.

Nitrones: not only extraordinary spin traps, but also good nitric oxide sources in vivo.

Free radicals are involved in the development of reperfusion injuries. Using a spin trap, the intensity of such lesions can be reduced. Nitrones (effective in vivo spin traps) were tried in this work as in vivo nitric oxide donors. Nitrite and nitrate concentration values (rabbit blood) were used as biomarkers of nitric oxide production. Most nitrones did not increase plasma concentrations of nitrite and nitrate; on the contrary, reduced plasma concentrations of these indicators were noted. However, glyoxal isopropyldinitrone, in a dose of 50 mg kg-1, was highly effective in increasing nitric oxide production. At the same time, nitrones do not react with hepatic homogenates, proving that the release of nitric oxide takes place in the tissues and is not related to hepatic metabolism. Before using nitrones in vivo, they were tested in vitro for the ability to release nitric oxide following a reaction with the hydroxyl radical.

Preparation and investigation of mefenamic acid - polyethylene glycol - sucrose ester solid dispersions.

Mefenamic acid (MA) is a widely used non-steroidal antiinflammatory (NSAID) drug. The adverse effects typical of NSAIDs are also present in the case of MA, partly due to its low water solubility. The aim of this study was to increase the water solubility of MA in order to influence its absorption and bioavailability. Solid dispersions of MA were prepared by the melting method using polyethylene glycol 6000 and different types (laurate, D-1216; palmitate, P-1670; stearate, S-1670) and amounts of sucrose esters as carriers. The X-ray diffraction results show that MA crystals were not present in the products. Dissolution tests carried out in artificial intestinal juice showed that the product containing 10 % D-1216 increased water solubility about 3 times. The apparent permeability coefficient of MA across human Caco-2 intestinal epithelial cell layers was high and, despite the difference in solubility, there was no further increase in drug penetration in the presence of the applied additives.

Growing patterns to produce 'nitrate-free' lettuce (Lactuca sativa).

Vegetables can contain significant amounts of nitrate and, therefore, may pose health hazards to consumers by exceeding the accepted daily intake for nitrate. Different hydroponic growing patterns were examined in this work in order to obtain 'nitrate-free lettuces'. Growing lettuces on low nitrate content nutrient solution resulted in a significant decrease in lettuces' nitrate concentrations (1741 versus 39 mg kg(-1)), however the beneficial effect was cancelled out by an increase in the ambient temperature. Nitrate replacement with ammonium was associated with an important decrease of the lettuces' nitrate concentration (from 1896 to 14 mg kg(-1)) and survival rate. An economically feasible method to reduce nitrate concentrations was the removal of all inorganic nitrogen from the nutrient solution before the exponential growth phase. This method led to lettuces almost devoid of nitrate (10 mg kg(-1)). The dried mass and calcinated mass of lettuces, used as markers of lettuces' quality, were not influenced by this treatment, but a small reduction (18%, p < 0.05) in the fresh mass was recorded. The concentrations of nitrite in the lettuces and their modifications are also discussed in the paper. It is possible to obtain 'nitrate-free' lettuces in an economically feasible way.

Nitrite and nitrate can be accurately measured in samples of vegetal and animal origin using an HPLC-UV/VIS technique.

Measurements of nitrite and nitrate are used in biomedical research to estimate the endogenous formation of nitric oxide (an important biomolecule). These anions are also toxins and their concentration is regulated in certain foodstuffs. There are many published methods for detecting nitrite and nitrate but most of them fail to detect nitrite in biological samples. A new HPLC-UV/VIS method was developed which easily detects low concentrations of nitrite and nitrate present in mammal blood, urine and in vegetal samples. The method is based on a pre-column derivatization of nitrite anion using the Griess reaction and direct determination of nitrate using its UV absorbance. A chromatographic process with detection at two wavelengths allows the determination of both anions in one run (23min with column reequilibration included). The limits of quantification in mammal blood are 2ng/ml and 200ng/ml for nitrite and nitrate, respectively. As regards vegetables, due to the need of sample dilution in the preparation steps, these limits are 3 times higher. Concentrations measured in rabbit blood samples ranged from 1.09 to 42.65µg/ml for nitrate and 15.8 to 384.6ng/ml for nitrite. Concentrations in vegetables ranged from below the limit of detection to 4g/kg for nitrate and from below the limit of detection to 369.2µg/kg for nitrite. The specificity of Griess reaction toward nitrite is under discussion since substances able to mimic this reaction were found, leading to compounds with spectral properties in visible domain indistinguishable from that of nitrite related azo dye.

Nitrones are able to release nitric oxide in aqueous environment under hydroxyl free radical attack.

Importance of a nitric oxide donor that can act as a spin trap might bring some new therapeutic possibilities regarding the treatment of ischemic diseases by reducing the intensity of free radical produced reperfusion lesions. These substances might be also used as a new type of photo protectors since they can absorb UV radiation, capture free radicals formed by interaction of UV radiation with tissue constituents, and tanning of the skin will be permitted due to nitric oxide release. The purpose of this work was to measure the ability of nitrones to release nitric oxide and how different factors (temperature, nitrone concentration, and free radicals) influence the releasing ability. Mostly, indirect determination of nitric oxide was carried out, by measuring nitrite and nitrate amounts (as decomposition products of nitric oxide), all nitrones proved to release significant amounts of nitric oxide. Nitrite measurements were made based on an HPLC-VIS method that uses pre-column derivatization of nitrite by forming an azo dye (limit of quantification: 5ng/ml). No good correlation was found between the amount of nitric oxide and temperature for most studied nitrones but between the formation of nitric oxide and nitrone concentration an asymptotic correlation was found. Fenton reagent also yielded formation of nitric oxide from nitrones and formed amounts were not different from those recorded for UV irradiation. Most of the nitrones effectively released about 0.5% of the maximum amount of nitric oxide that is chemically possible and estimated concentrations of 0.1µM were present in the solutions during decomposition.

The quantitative characterization of free radical sources and traps by electromigration applications.

Nowadays, very diverse human activities generate urgent demands for fast, sensitive reliable innovative tools capable of detecting major industrial, military, and other dangerous products. An important part of these compounds are free radicals. Capillary electrophoresis (CE), especially in its miniaturized format (lab-on-a-chip), and other electromigration methods offer special possibilities to resolve this problem. These measurements have a great opportuness because of very wide chemical and biological role of free radicals. Several compounds, e.g. monomers and some biologically important groups (as are nitrones) oppose oxidative challenges by virtue of their trap very rapidly oxygen- or carbon-centered radicals and generating other radical species which are stable and biochemically less harmful than the original ones. In many cases, conventionally, the relative trap capacity is measured against tert.-butylhydroperoxide (TBH). In this lecture are presented numerous important free radical species (active oxygen-, nitrogen- and carbon-centered ones, as HO, NO etc) and their adequate in vitro and in vivo applied bioanalytical methods, including liquid chromatography with electrochemical detection and mass spectrometry, gas chromatography with mass spectrometry, capillary electrophoresis, electron spin resonance and chemiluminescence analysis. A simple and highly sensitive method is the capillary zone electrophoresis with amperometric detection (CZE-AD); It was introduced to determine indirectly OH by analysing its reaction products with salicylic and dihydroxybenzoic acids. Hydroxylated radical products of these acids are often used as a relative measurement in free radical research. Accurate determination of pK(a) values is important for proper characterization of newly synthesized molecules. CZE method was used for determination of their values. Are initiated new research fields as Fenton-, electro-Fenton and photoelectro-Fenton chemistry and foreseen their perspectives. Nitric oxide is an important cell signaling molecule in physiology and pathophysiology. An indirect method for monitoring nitric oxide (NO) by determining nitrate and nitrite by microchip capillary electrophoresis (CE) with electrochemical (EC) detection has been developed. The amount of nitrite formed in this reaction (analyzed by capillary electrophoresis) was compared with the amount of oxygen consumed (measured by polarography). Were observed a linear relationship between the amount of consumed oxygen and the amount of nitrite formed in the measured range. These results demonstrate that polarographic measurements of the amount of oxygen consumed in the reaction with NO could be used to estimate the concentration of dissolved NO in authentic media. Polarography is an adequate method also to quantitative kinetic study of the free radical activity and of the trapping capacity of different compounds. This method is based on measure of the catalytic polarografic current of Fe(III) in the presence of free radical sources (TBH, hydrogen-peroxydes), and their traps. Personal contribution of the authors in this field is discussed.