Biomedical subjects

G Feroci

Publications and source records attributed to G Feroci.

5 recordsLinked to original sources

PubMed1998

Study of the antioxidant effect of several selenium and sulphur compounds.

Four selenium derivatives (sodium selenate, sodium selenite, selenourea and selenomethionine) and the sulphur analogues (sodium sulfate, sodium sulfite, thiourea and methionine), together with urea, were examined by means of polarography to study their reactivity towards superoxide ion O2. In order that experimental results could be applied to physiological conditions and to control the electroreduction of oxygen, most reactions were carried out in model systems (in the presence and in the absence of triphenyl phosphine oxide and at increasing pH) which are briefly described and discussed. Sodium sulfite and thiourea react with molecular oxygen; selenourea originates an anodic wave, although under other pH conditions. Other compounds (selenate, selenite, seleno-methionine and methionine) display an interesting antioxidant capacity because they catalyse the disproportion of the superoxide ion, as documented by the increase in the limiting current. Methionine appears to be particularly efficient in this respect, since it retains its catalytic ability in a poorly protic environment. Experimental results support the view that exogenous compounds, administered for particular purposes, can display unanticipated, and sometimes positive, side effects.

Antioxidants↗

PubMed1997

Interaction of iron(II) with bile salts.

Iron(II) ions react with small aggregates of cholate, glycocholate, chenodeoxycholate, and deoxycholate to form soluble and colloidal compounds. Taurocholate under conditions used does not react with the Fe2+ ion. Small aggregates of dihydroxy bile salts (predominating in the premicellar region, at concentrations of the bile salt above 1 mmol dm-3) have a larger affinity for Fe2+ compared to those formed from cholate anions. In their interactions with small aggregates of cholate anions, the Fe2+ ion shows an affinity comparable to that of Cu2+ and Cd2+ and somewhat larger than that of Zn2+. Small aggregates of cholate show a higher ability to mask Fe2+ than those of taurocholate and glycocholate. Interaction of glycocholic acid anions with Fe2+ ions is sufficient to prevent iron(II) precipitation.

Anions↗

PubMed1996

Interaction between trace elements: selenium and cadmium ions.

The interaction between several inorganic and organic selenium-containing compounds (selenite, selenate, selenourea and selenomethionine) and Cd2+ ions was studied by polarography. The changes in polarographic currents and half-wave potentials of the metal ions as a function of the Se-derivative concentration were followed. Experimental results suggest a different behaviour depending on the oxidation state of selenium. Any interaction between selenate and Cd2+ ions can be excluded. In the case of selenite, the presence of complexes in the solution was demonstrated. The shift in the Cd2+ reduction half-wave potential when a relatively high concentration of selenourea is present indicates formation of complexes, while the decrease in limiting current reflects the limited solubility of the complex itself. Results concerning selenomethionine suggest a very weak interaction with Cd2+ ions. These preliminary results are discussed in comparison with previous findings in cellular systems and may prove helpful in understanding cadmium ion toxicity and the in vivo altered distribution of various metal ions following the administration of selenium compounds.

Cadmium↗

PubMed1995

Interaction between Cu2+ ions and cholic acid derivatives followed by polarography.

Interaction of bile salts with Cu2+ ions in unbuffered systems containing 0.15 M NaNO3 was followed by measuring polarographic limiting currents and half-wave potentials. Whereas taurocholate forms neither soluble complexes nor compounds of limited solubility, cholate, glycocholate, and dehydrocholate from both soluble complexes and slightly soluble salts of copper(II) with small aggregates of bile salts. The stability of soluble complexes is comparable for cholates, dehydrocholates, acetates, and acetylglycinates, but smaller for glycocholates. The solubility of the copper(II) salts with small aggregates decreases in the sequence: glycocholate > cholate >> dehydrocholate. It is proposed that these salts are formed by interaction of a copper(II) ion with two carboxylic groups located on the small aggregate in a sufficiently small distance. In the presence of excess cholate the precipitated copper(II) salts are dissolved. It is assumed that at high bile salt concentrations, where precipitates are not observed, larger aggregates are formed that have free carboxylate groups, which increase their solubility in aqueous solutions. For glycocholate, within the accessible concentration range and within the time-frame used (24 h for the establishment of the equilibrium), the formation of such larger aggregates was not observed, even when its "cmc" is comparable with that of cholate. The absence of formation of larger aggregates for dehydrocholate parallels its tendency not to form "micelles".

Carboxylic Acids↗

PubMed1994

Interaction between reactive oxygen species and coenzyme Q10 in an aprotic medium: a cyclic voltammetry study.

The involvement of coenzyme Q (CoQ) as an antioxidant agent in several oxidative processes both in vitro and in vivo is nowadays pointed out by several biochemical and clinical studies, but the chemical mechanisms of this action are not yet unequivocally established. Electrochemistry provides very useful techniques for the analysis of the kinetics and thermodynamics, and mechanisms of chemical phenomena involving electron transfers, e.g. in the case of radical reactions. In the present study we used cyclic voltammetry to investigate the interactions between oxygen radicals and ubiquinone in aprotic medium, a condition similar to that existing in the biological membranes. The results obtained showed that ubiquinone is more easily reduced than oxygen, ruling out the possibility of an electron transfer from semiquinone to oxygen to produce superoxide radicals. On the contrary, it was demonstrated that fully reduced quinone is able to scavenge the superoxide radical, by reduction to peroxide ion, lowering actually the oxidative potential in the medium.

Antioxidants↗