5 research outputs found

    Role of the caffeic acid oxidation products on the iron mobilization at the soil-root interface

    Get PDF
    Previous results show that the reduction of Fe(III) by caffeiic acid (CAF) is strongly influenced by the pH of the reaction medium (DEIANA et al., 1995). In particular, it has been found that al pH > 3.8 the reducing activity of CAF towards the Fe(III) ions in solution is low, but it increases when Fe(III) is complexed as Fe(III)-polygalacturonate. The mobilization of the Fe(II) ions, which form upon the Fe(III) reduction, has been shown to depend mainly on the nature of the Fe(III)-polygalacturonate complexes (DEIANA et al., 1994a). In particular, it bas been observed a high redox activity of CAF towards Fe(III) when the metal ion is coordinated by the carboxilic groups of the macromolecule. The Fe(III) reduction has been found to decrease when an oxydrilic group was inserted in the Fe(III) coordination sphere. The Fe(II) produced partly diffuses into the external solution and partly is still strongly held by the polysaccharidic matrix. The oxidation of CAF by Fe(III) gives rise to the formation of products (OP) with different polymerization degree, some of which are similar to those found in natural systems (DEIANA et al., 1994b). In order to determine the role of these products in the Fe(III) reduction as well as in the mobilization of the Fe(II) produced it was set up an electrochemical method to synthetize these products (DEIANA et al., 1994b). Here are reported some results about the interaction which establish between the CAF oxidation products and iron in both oxidized and reduced form

    Sieroprevalenze di CAEV, MAP e CpHV1 in capre allevate in Sardegna e loro effetti sulle caratteristiche del latte

    No full text
    The aim of this thesis is to investigate whether seropositivity to CAE (caprine arthritis), PTB (paratuberculosis) and CpHV1 (goat herpesvirus type 1) may influence the coagulative characteristics of goat milk and its cheese yield. 1272 samples of milk and serum have been collected from goats distributed in 35 farms in Sardinia. The milk was analyzed for chemical parameters such as fat, protein, lactose, pH, somatic cell count and total bacterial load. The milk was also tested with the lactodynamography test for the classic parameters (RTC, K20, A30) and for the modeling parameters, while the nanocaseification was performed on 560 randomly extracted samples. Antibodies were investigated for the three pathologies with the ELISA technique for CAEV and PTB, and with serum neutralization for CpHV1. Data was analyzed using statistical software. The results obtained show a wide diffusion of the three pathologies with high prevalence rates. Although productions tend to be better on average in subjects with negative CAEV, PTB and CpHV1, no significant statistical associations have been observed, therefore seropositivity does not seem to negatively influence the capacity of cheesemaking milk of goats affected by these diseases. The control of these diseases in the future will be crucial

    Interaction of oxidation products from caffeic acid with Fe(III) and Fe(II)

    No full text
    Phenolic substances in the soil–plant system can be oxidized by metal ions, inorganic components, molecular oxygen as well as by phenoloxidases, giving rise to the formation of products of low or high molecular weight. Interactions of these products with iron, in both reduced and oxidized form, can affect the iron mobility in soil and rhizosphere, and thus its availability to plants. Here we report the results of a study on the complexing and reducing activity of the oxidation products from caffeic acid (CAF), obtained via electrochemical means, towards Fe(III) and Fe(II) in aqueous solution in the 3.0–6.0 pH range. The HPLC analysis of the filtered solutions after the CAF oxidation showed the formation of two main groups of products: (i) CAF oligomers formed through radicalic reactions which do not involve the double bond of the CAF lateral chain and (ii) products where this bond is involved. These oxidation products (COP) were found to interact with both Fe(III) and Fe(II) with formation of soluble and insoluble Fe(III)‐, and Fe(II)‐COP complexes. The COP were found to be able to reduce Fe(III) to Fe(II) mainly at pH < 4.0. A low redox activity was observed at pH ≥ 4.5 due to Fe(III) hydrolysis reactions as well as to the decrease in the redox potential of the Fe(III)/Fe(II) couple. Formation of hydroxy Fe(III)‐COP polymers occurs at pH > 3.5
    corecore