Biomedical subjects

M Bartosz

Publications and source records attributed to M Bartosz.

6 recordsLinked to original sources

PubMed1999

Antioxidant activity: what do we measure?

Inhibition of oxidation of 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) by free radicals generated by decomposition of 2,2'-azobis(2-amidopropane) (ABAP) by antioxidants and biological material was studied. A correlation was found between the ability of various substances to delay the onset of ABTS oxidation and their rapid reduction of the ABTS+* cation radical, and between the ability to reduce the maximal rate of ABTS oxidation and slow reduction of ABTS+*. The length of the lag period of ABTS oxidation was found to be independent of ABTS concentration. Similar decrease of peroxynitrite-induced ABTS+* formation by antioxidants was observed when the antioxidants were added before and after peroxynitrite. All these findings indicate that the main effect of antioxidants in this system is reduction of ABTS+* and not prevention of its formation. Reduction of oxidation products rather than inhibition of their formation may be the predominant mode of action of antioxidants in various assays of antioxidant activity.

Amidines↗

PubMed1998

Simple determination of peroxyl radical-trapping capacity.

A simple spectrophotometric method of determination of peroxyl radical-trapping capacity (PRTC) of body fluids and food products is proposed. In this method, decomposition of 2,2'-azobis(2-amidopropane) hydrochloride (ABAP) is the source of peroxyl and alkoxyl radicals which oxidize 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) to a green cation radical. Antioxidant present in a sample inhibit the reaction; the induction time of the reaction is proposed as a parameter enabling determination of antioxidant content. Standard assay conditions are: 20 mM ABAP and 150 microM ABTS in 0.1 M phosphate buffer, pH 7.0, at 37 degrees C; absorbance is monitored at 414 nm. A 10-min assay allows for determination of the induction time of appropriately diluted sample. As examples of application of this method, PRTC values of several types of beverages are reported.

Alcoholic Beverages↗

PubMed1997

Antioxidant and prooxidant properties of captopril and enalapril.

Captopril ([2S]-1-[3-mercapto-2-methyl-propionyl]-L-proline) was found to protect erythrocytes from hemolysis caused by 2,2'-azobis (2-amidinopropane) (AAPH) and hypochlorite, erythrocyte membranes from lipid peroxidation caused by tert-butyl hydroperoxide (tBOOH) and hypochlorite, erythrocyte membrane ATPases from inactivation caused by tBOOH and hemoglobin from oxidation caused by AAPH and tBOOH. In all these systems enalapril ([S]-1-[N-(1-[ethoxycarbonyl]-3-phenylpropyl)-L-alanyl]-L-proline) was not protective or even increased the damage, especially with hypochlorite, probably due to chloramine formation. Captopril but not enalapril inhibited ascorbate autoxidation caused by Cu2+, which indicates that captopril binds Cu2+. On the other hand, deoxyribose degradation caused by iron and copper ions and DNA damage by o-phenanthroline/Cu2+/H2O2/beta-mercaptoethanol was enhanced by both captopril and enalapril. The effect of captopril was usually higher, apparently due to the reducing properties of captopril, which could reduce metal ions enabling their participation in the Fenton reaction. These results indicate that only -SH-group-containing inhibitors of angiotensin-converting enzyme (ACE) may exhibit antioxidant properties, and that the antioxidant/prooxidant action of ACE inhibitors depends on the system studied in vitro.

Adenosine Triphosphatases↗

PubMed1996

The copper complex of captopril is not a superoxide dismutase mimic. Artefacts in DMPO spin trapping.

The effect of captopril and of its copper complex on several superoxide-dependent reactions used to detect and assay superoxide dismutase activity was studied, including pyrogallol and hematoxylin autoxidation and Nitro Blue Tetrazolium reduction. In none of these systems were superoxide dismutase-like properties of captopril/Cu apparent. Captopril/Cu decreased the yield of DMPO-OH adducts generated by KO2 but this effect may be due to the acceleration of the decay of the adduct by captopril/Cu.

Antioxidants↗

PubMed1994

Stimulation of erythrocyte membrane Mg(2+)-ATPase activity by dinitrophenol and other membrane-disturbing agents.

Erythrocyte membrane Mg(2+)-ATPase activity was stimulated by echinocytogenic agents (2,4-dinitrophenol and salicylate), a stomatocytogenic agent Triton X-100 and other membrane-disturbing agents including hydrophobic organic anions, alcohols and detergents. Various possible mechanisms of the stimulation are possible but apparently most probable one consists in induction of membrane phospholipid scrambling by the compounds studied (as demonstrated for DNP) and of aminophospholipid translocase (flippase) activity.

2,4-Dinitrophenol↗

PubMed1988

Phagocytosis and killing of Listeria by guinea pig macrophages and neutrophils.

The rate of the phagocytosis and intracellular killing of Listeria monocytogenes by guinea pig macrophages and neutrophils in vitro was determined. The anti-bacterial activity of the phagocytes against virulent Listeria monocytogenes was compared with their activity against avirulent strain of Listeria and Proteus mirabilis. It is suggested that the contribution of the macrophages and the neutrophils to anti-bacterial protection can depend on physiological state of bacteria.

Animals↗