Browsing by Author "VALENZUELA, A"

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    FLAVONOIDS AS STABILIZERS OF FISH-OIL - AN ALTERNATIVE TO SYNTHETIC ANTIOXIDANTS
    (1993) NIETO, S; GARRIDO, A; SANHUEZA, J; LOYOLA, LA; MORALES, G; LEIGHTON, F; VALENZUELA, A
    The antioxidant activities against fish oil oxidation of six commercially available flavonoids and of five flavonoids purified from two Chilean native plants were compared to those of dl-alpha-tocopherol and of two synthetic antioxidants, butylated hydroxytoluene and butylated hydroxyanisole. Among the commercial flavonoids, catechin, morin and quercetin showed a higher activity when fish oil oxidation (either spontaneous or Fe2+-induced) was assessed from the formation of peroxides or thiobarbituric acid-reactive substances. Among the native flavonoids, the 5,3',4'-trihydroxy-7-methoxy flavanone (designated as Pt-2) showed the highest antioxidant activity. Mixtures of quercetin or of Pt-2 with dl-alpha-tocopherol produced better inhibitory effects when compared to that of each substance assayed by itself. Also, when Pt-2 and quercetin were assayed in combination (0.3 g/kg oil and 0.7 g/kg oil, respectively), a synergistic antioxidant effect was observed. Results indicate that several flavonoids could be used as natural antioxidants as a means to replace those synthetic antioxidants, the use of which has been questioned.
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    RIBOFLAVIN STATUS AND PHOTOINDUCED RIBOFLAVIN BINDING TO THE PROTEINS OF THE RAT OCULAR LENS
    (1988) SALIMHANNA, M; VALENZUELA, A; SILVA, E
    The presence of radioactivity in lenses of rats injected intraperitoneally with a solution of tryptophan and 14C-riboflavin, irradiated during 48 hours and under N2 atmosphere, was detected. The excitation fluorescence spectrum (.lambda.emission = 520 nm) of the soluble lens fraction corresponds to the riboflavin decomposition product of lumichrome type. When 14C-riboflavin enriched lenses were exposed to visible light, a photo-induced binding between riboflavin and a water insoluble protein fraction of the lenses was observed. This finding may help to clarify the lens modifications during aging and in cataractogenesis.
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    TRYPTOPHAN-RIBOFLAVIN PHOTOINDUCED ADDUCT AND HEPATIC-DYSFUNCTION IN RATS
    (1988) DONOSO, MDN; VALENZUELA, A; SILVA, E