ABSTRACT:The effect of the stage of lactation on blood redox homeostasis of bovine and buffalo cows was evaluated. The investigation was carried out on early lactating and mid-late lactating cows, reared in a farm located in Campania (southern Italy). Plasma concentration of α-tocopherol and ascorbate, the total antioxidant capacity (TAC), glutathione peroxidase (GPx), and superoxide dismutase activities were higher (P < 0.01) in mid-late lactating cows, thus suggesting a higher consumption of antioxidants during early lactation. Plasma concentration of protein-bound carbonyls (PC) and nitrotyrosine (N-Tyr), and the level of lipid hydroperoxides (LPO) were higher (P < 0.01) in early lactating cows, thus suggesting that lipid peroxidation and peroxynitrite production are crucial in determining oxidative modifications in plasma. TAC was positively correlated with ascorbate concentration (P < 0.03), and negatively correlated with PC concentration (P < 0.002), and ascorbate was negatively correlated with PC (P < 0.03) in mid-late lactating group. These findings demonstrate that circulating ascorbate plays a major role in preventing protein modifications induced by carbonyls, and that ascorbate scavenging effect is impaired during early lactation. We calculated a protein oxidative stress index as the ratio (PC + N-Tyr)/TAC multiplied by 100, and we found that this parameter was higher (P < 0.0001) in early lactating cows. Therefore, it could be useful for assessing the extent of protein oxidative damage in relation to the whole antioxidant status. Further, we suggest that the LPO/GPx ratio multiplied by 100 might be used as lipid oxidative stress index in lactating cows. This index was higher (P < 0.0001) in early lactating cows, and might represent a standard parameter for evaluating the lipid damage depending on a deficiency of the enzymatic antioxidant defence. These parameters are proposed for a possible effective description of physiological changes associated with lactation.

Phenylpropanoid glycosides (PPG), like other phenolic compounds, are a powerful antioxidants and the Verbascoside (VB) is one of the most active of them. A previous study, by using in vitro exposure of blood human lymphocytes to Verbascoside, reported a significant increasings of chromosome fragility compared to control. In the present study, four homogeneous groups of rabbits were used to test in vivo the VB and/or Lycopene (LP) by feeding the animals without VB and LP (control), in presence of VB or/and LP for 80 days. Lymphocyte cell cultures were performed in three different times: 0, 40 and 80 days of the experiment and the cytogenetic tests that we used [CA-test (Chromosome Abnormalities in terms of chromosome and chromatid breaks) and Sister Chromatid Exchange (SCE-test)] have revealed no mutagenic effects on chromosomes. Indeed, mean values/cell of CA and SCE decreased during the experiment with some difference among and within groups, with significant decreasing value only for some group. The study shows clear evidence that diets rich in Verbascoside (and/or Lycopene) do not originate any mutagenic activity, resulting no cytotoxic for the animals and, suggesting a possible their use in both animal and human diets.

Dioxins are lipophilic compounds with a small molecular weight and are highly persistent, bioaccumulative and toxic. Dioxin detoxification is associated with an increased production of reactive oxygen species (ROS). In physiological conditions the body is protected against ROS and their toxic products by a wide range of antioxidant systems. We hypothesize that the imbalance between ROS production, associated with dioxin exposure, and the antioxidant defence capacity, may lead to oxidative stress, with consequent increased consumption of antioxidants and accumulation of toxic compounds in blood and tissues. The objective of this study was to evaluate the effect of exposure to dioxins on the plasma redox status of lactating buffalo cows. To this aim, the major liposoluble (retinol and α-tocopherol) and water-soluble (ascorbate) antioxidants, the superoxide dismutase (SOD) and glutathione peroxidase (GPx) activity, the total antioxidant capacity (TAC), as well as specific protein oxidation markers (protein bound carbonyls and nitro-tyrosine) and lipid oxidation markers (hydroperoxides), were chosen as indices of blood redox status. The concentration of antioxidants, protein-bound carbonyls (PC), nitro-tyrosine (N-Tyr), and hydroperoxides (LPO), the SOD and GPx activity, and the TAC were measured in plasma samples obtained from buffalo cows exposed to environmental levels of dioxins higher (n=21, group A) or lower (n=29; group B) than those permitted. Plasma titres of antioxidants, as measured by HPLC, and the total antioxidant capacity, as measured by trolox equivalents capacity, were higher in group B than in A. Similarly, SOD and GPx activities were higher in group B than in A. Conversely, plasma levels of PC, N-Tyr and LPO, as measured by ELISA, were higher in group A than in B. Our results suggest that exposure to dioxins impairs the plasma antioxidant defence system of lactating buffalo cows, and that metabolic processes associated with dioxin detoxification might induce or enhance oxidation of protein and lipids. This adverse effect on blood redox status might have negative implications for animal health and reproduction, and might compromise animal welfare.