Sara Noemi

... Nelly LAVINTMAN, Juana TANDECARZ, Marta CARCELLER, Sara MENDIARA, and Carlos E. CARDINI Instituto de Investigaciones Bioquimicas “Fundacion Campomar” and Facultad de Ciencias Exactas y Naturales, Buenos Aires (Received May 27/September 9, 1974) ...

Free radical scavenging properties of hepatopancreas extracts of Pleoticus muelleri were evaluated by electron paramagnetic spin resonance spectrometry methods (EPR) against the stable 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical. The present study was carried out to characterize different physiological stages of the shrimp under environmental and nutritional stress, evaluating the effect on growth, survival, and functional morphology of the hepatopancreas. Feeding trials were carried out on juveniles (1 g initial weight) held in aquaria. Each diet, with different concentrations of vitamins A and E, was tested in triplicate groups during 25 days. The control groups were fed with fresh squid mantle and with a vitamin-free diet. For all of the diets, the extracts exhibited strong DPPH radical scavenging activity, suggesting that the tissue is a powerful natural antioxidant. Individuals fed with different concentrations of vitamin E showed the strongest effect on the DPPH radicals, reducing the DPPH radicals to 50%, after an incubation period of 3 min. In contrast, the extracts of control animals, fed with squid mantle, had the weakest antioxidant activity (4%). These data indicated that the presence of vitamin E in the diet can provide immediate protection against free radicals.

The purpose of this study was to measure the concentration of carotenoids and properties which occur in tissues to neutralize free radicals during ontogeny of Pleoticus muelleri. The stages of nauplius, protozoea, mysis and postlarvae of 1, 6, 10, 26, 30 days were examined from hatchery raised postlarvae from wild females. The β-carotene and the astaxanthin from the lyophilized tissue

.  The equilibrium of the reaction galvinoxyl radical + 4,4′-methylene-bis(2,6-di-tert-butyl-phenol) (IOH) ⇆ hydrogalvinoxyl + 4,4′-methylene-bis(2,6-di-tert-butyl-phenoxyl radical) was monitored by electron paramagnetic resonance spectroscopy between 213 and 293 K. The equilibrium constant was calculated for each temperature point and correlated to T −1 applying the Van't Hoff relationship lnK R = (−ΔH R 0/RT) + (ΔS R 0/R). The reaction enthalpy was

On the basis of previous and current studies, it has been possible to evaluate and compare the bond dissociation energies of the phenol (O–H) bond and of the methylene and methyl (C–H) bonds in Irganox (trade name) by means of electron paramagnetic resonance records of galvinoxyl–irganoxyl hydrogen transfer reaction equilibria. The bond dissociation enthalpy of the C–H methylene and methyl

ABSTRACT Ultraviolet and visible spectroscopy was applied to characterize and to measure the concentration of β-carotene dissolved in a dioxane and water mixture. The reaction of β-carotene in the presence of nitrite anion and acid medium was studied at different temperatures. The reaction systems were homogeneous and were kept anaerobic. Pseudo-first-order rate constants in respect of β-carotene were measured in the range from 293 to 313 K and pH 5.8 ± 0.2. The energy of activation was calculated to be E a = 67.2 ± 3.4 kJ/mol. We interpolate a value that may have biological interest, k β-carotene(310 K) = (9.70±0.78) · 10−3 s−1, in the presence of 9.3 · 10−3 M nitrite anion. Electron paramagnetic resonance spectroscopy was applied to characterize and quantify a persistent intermediate radical generated in the reaction system described. The recorded spectra showed triplet-type signals with a peak-to-peak value of 12.7 G. Nearly the same triplet radical-type intermediates were detected when studying the following reaction systems in pure dioxane: nitrogen dioxide (NO2)/β-carotene, nitric oxide (NO)/β-carotene and NO/NO2/β-carotene. Therefore, we proposed that the nitrogen oxides have also been intermediates in the reaction system of β-carotene, nitrite anion and acid medium, in the dioxane and water mixture. A mechanism was proposed and checked by employing the chemical kinetics simulation. The explanations developed would lead to a better understanding of the behavior of carotenoids in the presence of nitrite anion and nitrogen oxides.