Flow injection analysis coupled with carbon electrodes as the tool for analysis of naphthoquinones with respect to their content and functions in biological samples

Naphthoquinones are one of the groups of secondary metabolites widespread in nature, where they mostly appear as chromatic pigments. They embody broad-range of biological actions from phytotoxic to fungicidal. An anticancer effect of naphthoquinones stimulates an interest in determination and characterization of single derivatives of 1,2- and 1,4-quinones in biological samples. The main aim of this work was to suggest a technique suitable to determine lawsone, juglone and/or plumbagin in biological samples and to study of their influence on BY-2 tobacco cells. The BY-2 tobacco cells were cultivated in the presence of the naphthoquinones of interest ( 500 mu g.l(-1)) for 24 h and then the morphological changes were observed. We found out that naphthoquinones triggered the programmed cell death at BY-2 cells, which can be confirmed by the apoptotic bodies in nucleus. After that we suggested and optimized different electrochemical techniques such differential pulse voltammetry ( DPV) coupled with hanging mercury drop ( HMDE) and carbon paste electrode, micro flow device coupled with carbon screen printed electrodes and flow injection analysis coupled with Coulochem III detector to determine them. The detection limits of naphthoquinones of interest were expressed as 3S/N and varied from units to hundreds of ng per millilitres according to methods used. Moreover, we utilized DPV coupled with HMDE and micro flow device to determine content of juglone in leaves Persian walnut ( Juglans regia). We determined that the leaves contained juglone tenths of g per 100 g of fresh weight. The results obtained show the convincing possibilities of using of these methods in analysis of plant secondary metabolites

Lead Ions Encapsulated in Liposomes and Their Effect on Staphylococcus aureus

The aim of the study was the preparation of a liposome complex with encapsulated lead ions, which were electrochemically detected. In particular, experiments were focused on the potential of using an electrochemical method for the determination of free and liposome-encapsulated lead and determination of the encapsulation efficiency preventing the lead toxicity. Primarily, encapsulation of lead ions in liposomes and confirmation of successful encapsulation by electrochemical methods was done. Further, the reduction effect of the liposome matrix on the detected electrochemical signal was monitored. Besides encapsulation itself, comparison of toxicity of free lead ions and lead ions encapsulated in liposome was tested. The calculated IC50 values for evaluating the lead cytotoxicity showed significant differences between the lead enclosed in liposomes (28 mu M) and free lead ions (237 mu M). From the cytotoxicity studies on the bacterial strain of S. aureus it was observed that the free lead ions are less toxic in comparison with lead encapsulated in liposomes. Liposomes appear to be a suitable carrier of various substances through the inner cavity. Due to the liposome structure the lead enclosed in the liposome is more easily accepted into the cell structure and the toxicity of the enclosed lead is higher in comparison to free lead ions

Hazards of secondary bromadiolone intoxications evaluated using high-performance liquid chromatography with electrochemical detection

This study reported on the possibility of intoxications of non-target wild animals associated with use of bromadiolone as the active component of rodenticides with anticoagulation effects. A laboratory test was done with earthworms were exposed to bromadiolone-containing granules under the conditions specified in the modified OECD 207 guideline. No mortality of earthworms was observed during the fourteen days long exposure. When the earthworms from the above test became a part of the diet of common voles in the following experiment, no mortality of consumers was observed too. However, electrochemical analysis revealed higher levels of bromadiolone in tissues from earthworms as well as common voles compared to control animals. There were determined comparable levels of bromadiolone in the liver tissue of common voles after primary (2.34 +/- 0.10 mu g/g) and secondary (2.20 +/- 0.53 mu g/g) intoxication. Therefore, the risk of secondary intoxication of small mammalian species feeding on bromadiolone-containing earthworms is the same as of primary intoxication through baited granules. Bromadiolone bio- accumulation in the food chain was monitored using the newly developed analytical procedure based on the use of a liquid chromatography coupled with electrochemical detector (HPLC-ED). The HPLC-ED method allowed to determine the levels of bromadiolone in biological samples and is therefore suitable for examining the environmental hazards of this substance

CoulArray Detector as a Tool for Estimation of Acute Toxicity of Silver(I) Ions

Biochemical markers suitable for monitoring of environmental pollution as well as for protecting of human health are searching. In this study, the effect of silver(I) ions on guppy fishes (Poecilia reticulata) was investigated. For this purpose, we employed hyphenated technique of high performance liquid chromatography coupled with multichannel CoulArray electrochemical detector. Content of cysteine in fishes treated with 0.5 and/or 1 mu g/l of silver(I) ions was 290 and/or 240 ng/g at the end of seven day long treatment. Reduced and oxidized glutathione were also determined. The enhance in GSSG content accompanied by decrease in GSH content confirms our hypothesis on increasing risk of oxidative stress in fishes due to treatment with silver(I) ions. In addition, we attempted to gain more information about health state of animals exposed to heavy metals from chromatograms measured by CoulArray detector. We counted areas of all signals detected up to 30 minutes in chromatograms of tissues from fishes treated with all concentrations of silver(I) ions. The content of thiols and thiols related compounds as a sum of signals areas enhanced with increasing concentration of silver(I) ions and time of exposition

Determination of Vitamin C (Ascorbic Acid) Using High Performance Liquid Chromatography Coupled with Electrochemical Detection

Vitamin C (ascorbic acid, ascorbate, AA) is a water soluble organic compound that participates in many biological processes. The main aim of this paper was to utilize two electrochemical detectors (amperometric - Coulouchem III and coulometric - CoulArray) coupled with flow injection analysis for the detection of ascorbic acid. Primarily, we optimized the experimental conditions. The optimized conditions were as follows: detector potential 100 mV, temperature 25 C, mobile phase 0.09% TFA: ACN, 3: 97 (v/v) and flow rate 0.13 mL.min(-1). The tangents of the calibration curves were 0.3788 for the coulometric method and 0.0136 for the amperometric one. The tangent of the calibration curve measured by the coulometric detector was almost 30 times higher than the tangent measured by the amperometric detector. Consequently, we coupled a CoulArray electrochemical detector with high performance liquid chromatography and estimated the detection limit for AA as 90 nM (450 fmol per 5 mu L injection). The method was used for the determination of vitamin C in a pharmaceutical preparations ( 98 +/- 2 mg per tablet), in oranges ( Citrus aurantium) ( varied from 30 to 56 mg/100 g fresh weight), in apples (Malus sp.) (varied from 11 to 19 mg/100 g fresh weight), and in human blood serum (varied from 38 to 78 mu M). The recoveries were also determined

Utilizing electrochemical techniques for detection of biological samples

Heavy metals rank among the most toxic compounds occurring in the environment; they are also dangerous due to bioaccumulation. Plants and animals have developed a number of protective mechanisms. The detoxification mechanisms of heavy metals in different organisms have been intensively studied for many years. We aimed at investigation of detoxification mechanisms of maize plants treated with 0, 50, 100, 150, 200, 400 and 500 μM Cd(II) solutions for six days. In particular, we observed their growth and determined the Cd content (by differential pulse anodic stripping voltammetry) and thiol concentration (by HPLC) in the treated plants. Maize plants took up 6 pg of Cd per gram per hour at the lowest dose and 23 pg Cd per g per hour at the highest Cd dose. The relations of glutathione and phytochelatin contents, applied Cd dose, cultivation time, growth curve and plant morphology were investigated

Palladium biosensor

In this paper we proposed a palladium(II) biosensor. The biosensor is based on determining of interactions between palladium(II) and metallothionein modified hanging mercury drop electrode by means of differential pulse voltammetry. We studied influence of two supporting electrolytes (potassium or sodium chloride) on the signals of the biosensor. Based on the results obtained we found potassium chloride (0.05 M) as the most suitable supporting electrolyte to determine palladium(II). The detection limit of the biosensor for palladium ions was evaluated as 100 nM with RSD about 10%. Moreover, we utilized the biosensor for measurement of the target molecule in the presence of human blood serum and human urine