Roberto Badiello

Pulse radiolytic study of hydrogen transfer from glutathione to organic radicals.

(1982). Pulse Radiolytic Study of Hydrogen Transfer from Glutathione to Organic Radicals. International Journal of Radiation Biology and Related Studies in Physics, Chemistry and Medicine: Vol. 41, No. 6, pp. 595-602.

On the chemical radioprotection by organic selenium compounds in vivo.

This paper deals with the radioprotection afforded by selenocystine, selenomethionine, colloidal selenium, selenoxanthene, selenoxanthone, and selenochromone in living rats. Our evaluation of radioprotection was based on the ability of the compounds to alleviate the mortality and the leukopenia occurring in rats exposed to irradiation of 600, 750, and 900 R. The results show that these compounds have an action similar to, and sometimes even superior to, that of cysteine. A preliminary study was made of the mechanism of action of the selenium derivatives by measurement of the retention of selenium in the blood, and its distribution at the subcellular level in the liver.

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.

Primary and Secondary Radicals in the Radiation-induced Inactivation of Yeast Alcoholdehydrogenase

SummaryRadiation inactivation of YADH in dilute aqueous solution that does not contain oxygen is due to H atoms and OH radicals, whose inactivating efficiencies are in the ratio 9 : 1. The same species are responsible for the transient absorption arising in pulse-irradiated YADH in the region of 300–320 nm, and in this case their relative efficiencies are 7·5 to 1. This resulted from steady-state and pulse radiolysis experiments using radical scavengers such as t-butanol, formate and N2O. It appears that oxygen, when present, may also contribute to the enzyme inactivation through its radiation-induced radicals. Secondary radicals originated by reaction of OH radicals with CNS−, Br− and I−, all inactivate the enzyme at a faster rate than their primary parent radical. Their relative inactivating efficiencies are of the same order as their rate constants for reaction with YADH.

I. The Terpene Marrubiin

The biosynthesis of the diterpene marrubiin has been studied using some labelled possible precursors: [2-14C] mevalonate, [1-14C] acetate, [2-14C] acetate, [2-14C] pyruvate, [2,3-14C] succinate, [1,4-14C] succinate, [5-14C] ketoglutarate and [1,5-14C] citrate. Metabolism times of 24, 36, 48, 72 and 96 hours were used. The labelled compounds were supplied in solution to flowering white horehound (Marrubium vulgare L.), cut at the base of the stem. The incorporation results indicate that marrubiin undergoes a rapid turnover with a biological half life of about 24 hours. The rate of up-take of 14C from the prcursors is in the following order: [2-14C] mevalonate, [2-14C] acetate, [1-14C] acetate, [2-14C] pyruvate and [2,3-14C] succinate. Incorporation of 14C from the other compounds is negligible. If [2-14C] mevalonate is used, labelled marrubiin is formed 10 - 100 times more active than with the other precursors. The results suggest that all the precursors are degradated to acetic units through the Krebs cycle before their utilization, with the exception of mevalonate. Some samples of marrubiin (I) have been degradated chemically to the corresponding ketoderivative (II), in order to determine the distribution of radioactivity between the decahydronaphthalenic and furanic parts. The results are in good agreement with the distribution of the radioactivity in the molecule, as expected from the terpenoid structure of marrubiin.

Further Observations on in vivo Radioprotection of Rats by Selenourea

Abstract This paper deals with a study of some tests in rats in vivo after gamma irradiation in the presence and in the ab sence of selenourea. The factors considered were the total protein content, the protein pattern, and some serum enzymes, like GOT, GPT and AP. The result shows that the preadministration of selenourea modifies fovourably the changes induced by ionizing radiation

Notizen: Pulse Radiolysis of Selenium Containing Compounds: Selenomethionine

The pulse radiolysis of aqueous solutions of selenomethionine has been studied under both neutral and acid conditions and the transient optical absorption spectra have been observed. The reactivities of both eāq and OH radicals have been measured as well as the formation and the decay kinetics of the transient species.

Rate of uptake of75Se, as selenourea-75Se, in rats in vivo

Die Geschwindigkeit der Verteilung und Fixierung des Selenharnstoff-75Se wurde in diversen Rattenorganen in vivo und bei Stoffwechselzeiten von 6 h bis zu 14 Tagen untersucht. Die Selenharnstoffmengen varierten zwischen 0,4 und 3,0 mg pro Tier.

The role o eneral metabolites in the biosynthesis of natural products. 3. The phytosterol 22, 23-dihydrostigmasterol.

The Authors have studied the role of some general metabolites in the biosynthesis of the 22,23-dihydrostigmasterol in Wistaria Sinensis flowers, gathered during the period April—July. The rate of uptake of the following possible precursors has been investigated: [2-14C] acetate, [2-14C] pyruvate, [2,3-14C] succinate, [1,4-14C] succinate, [1,4-14C] fumarate, [5-14C] ketoglutarate, [1,5-14C] citrate and [2-14C] mevalonate. Metabolism periods of 12, 24, 36, 48 and 72 hours have been used. Mevalonate and acetate have shown the highest degree of incorporation, as in agreement with the known data on their role in the biosynthesis of sterols. The incorporation of radioactivity from [2,3-14C] succinate has been significant from the other compounds negligible. Some metabolic relationships have been found especially among acetate, pyruvate, succinate and the other substances involved in the Krebs cycle.