ABSTRACT
Phenolic acids and flavonoids were characterized by cyclic voltammetry and total antioxidant activity in the reaction with the ABTS cation radical. Anode peak voltages (Eap) and their pH dependences were determined for the studied phenolic acids and flavonoids. The Eap and Trolox equivalent antioxidant capacity (TEAC) values were found to correlate for polyphenols, which react with the ABTS cation radical in two steps. Correlation between the half-wave potential (Ep/2) and TEAC was determined for electrochemically irreversible compounds. Mechanisms of the reaction of phenolics on the electrode involving one- and two-electron oxidation are proposed.
Subject(s)
Antioxidants/chemistry , Flavonoids/chemistry , Hydroxybenzoates/chemistry , Phenols/chemistry , Plants/chemistry , Potentiometry/methods , Hydrogen-Ion Concentration , Kinetics , Molecular StructureABSTRACT
An express electrochemical method for determining the metabolic activity of live cells based on the possibility of an electron exchange between an electrode and elements of the biological electron transfer chain in the presence of a mediator is proposed. This method is useful for studying any live cells (animal, plant, and microbial), including anaerobic, dormant, and spore cells. The sample preparation and measurement itself does not take more than 30 min. The detection limit in a volume of 15 ml amounts to 10-5 cells/ml. The applicability of the assessment method of the metabolic activity level during the transition of the bacteria Mycobacterium smegmatis into an uncultivable dormant state was demonstrated. This method is of special value for medicine and environmental control, detecting latent forms of pathogens. An optimal combination of the methods for the express analysis of latent pathogens is proposed.
Subject(s)
Mycobacterium smegmatis/physiology , Electrochemistry/methods , Electrodes , Mycobacterium smegmatis/cytologyABSTRACT
Dynamics of transformation of Mycobacterium smegmatis cells by cultivation under nonoptimal conditions (partial starvation) to dormant, nonculturable form has been studied. For this aim, an electrochemical method was developed to detect both viable and 'viable but nonculturable' (VBNC) cells. The current produced by bacteria placed at the electrode surface was measured in the presence of 2,6-dichlorophenol indophenol (DCIP) at the applied potential of 350 mV. It has been established that electrochemical activity changes parallel with the growth of biomass. The transition of M. smegmatis to a dormant, nonculturable state goes along with the decrease of the detection current up to 20% of the maximum level. This means that nonculturable cells have rather high rest metabolic activity. The course of the CFU values has a complicated character during bacterial growth. The placement of the bacterial culture on the solid medium appears to cause a new stress that stops proliferation and stimulates aggregation. Both processes distort CFU measurement results. The quantitative estimation of the viable but nonculturable cells by counting colonies, measuring optical density and current produced by bacteria has been discussed.
Subject(s)
Mycobacterium smegmatis/growth & development , 2,6-Dichloroindophenol , Cell Proliferation , Cell Survival , Electrochemistry/methods , Electrodes , Mycobacterium smegmatis/chemistry , Mycobacterium smegmatis/isolation & purificationABSTRACT
By means of polarography and tree-angle scan voltammetry, AdoCbl, MeCbl and OH-Cbl were studied in mixtures and separately. The possibility to obtain a polarographic scope of quality for each of the natural cobalamins studied was shown. The ability of cobalamins to be adsorbed on a mercury electrode enables to increase the sensitivity of the method by conducting the accumulative adsorption from solutions with the concentration up to 1 microgram/ml.
Subject(s)
Polarography/methods , Vitamin B 12/analysis , Adsorption , Electrodes , SolutionsABSTRACT
AdoCbl, MeCbl and OH-Cbl were studied by methods of polarography and three-angle scan voltammetry. Cobalamines studied show a specific electrochemical activity that can be taken as a basis for their identification after separation and purification. The high sensitivity of the method allows to carry out the quantitative analysis of AdoCbl at concentrations ranging from 10(-6) M to 10(-4) M.
Subject(s)
Cobamides/analysis , Polarography/methods , Vitamin B 12/analysis , Electrochemistry , Polarography/instrumentation , SolutionsABSTRACT
The electrochemical behaviour of the electron transfer proteins -- cytochromes b5, c and P-450 was studied by classical polarography and electrolysis with spectrophotometric monitoring. It was shown electrons are directly transferred from the electrode to oxidized cytochromes c and b5. Cytochrome P-450 is not reduced on the electrodes. However, the reduced inactivated from of cytochrome P-420 was detected at high potential values (-1,5 v).
