Browsing by Author "Porubin, Diana"

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    ACTIVITATEA ANTIOXIDANTĂ A UNOR COMPUŞI DIN PRODUSE SECUNDARE VINICOLE LA REDUCEREA NITRITULUI
    (CEP USM, 2007) Gonţa, Maria; Porubin, Diana
    In the stomach, the dietary nitrite reacts with the nitrosable substrates (amines, amides, etc.) forming carcinogenic N-nitroso compounds. The process of inhibition of NOC formation is based on the reduction of the nitrite to NO, which is not a direct nitrosating agent. Considering all this, we have decided to study the nitrite reduction, using various com-pounds, as: quercetin (Que), (+)catechin ((+)Ct), rezveratrol (Rezv), dihydroxyfumaric acid (DFH), the dimethylic ester of the dihydroxyfumaric acid (EDMD), the dimethylic ester of the tartaric acid (EDMT) and ascorbic acid (AA) used as reference. We obtained that the increase of the reductants concentration leads to the increase of the reduction rate of nitrite, which indicates the existence of a dose dependent effect. The reduction rate was investigated function of the pH value: 1.5, 2.6, 3.4, 4.6 and 5.6. The reductants and nitrite concentrations were of 1·10-4 M. The best results were obtained at pH 1.5 for all reductants. Thus, the pH has a direct influence on nitrite reduction. The most efficient nitrite-reducing agents are Cver, (+)Ct, Rezv, and DFH4, followed by EDMD and AAs, whereas EDMT showed very weak antioxidant properties. This can be explained by the chemical structure of the investigated compounds and their behavior in various reaction media.
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    INHIBITION OF IN VITRO NITROSATION OF NORNICOTINE
    (Academia de Știinițe a Moldovei, 2007) Porubin, Diana
    The inhibition of nornicotine nitrosation was studied. The concentration of nornicotine was 100 μM and nitrite 1000 μM. As inhibitors were used following compounds: ascorbic acid (as reference) (800, 1000, and 5000 μM), dihydroxyfumaric acid (1000 μ M), (+)catechin (1000 μM), resveratrol (1000 μM), tartaric acid (1000 μM), quercetin (1000 μM), and grape seed extract (50, 100, 150 μg/ml). The best inhibitory effect was obtained for AAs at 5000 μM (90.7%), (+)Ct (95.5 %) and GSE at 150 μg/ml (96.1%). The small inhibitory effect was observed for TA – 22,5%.