In this work, the spectrophotometric studies on the kinetics of redox reaction between gold(III) bromide complexes and sodium nitrite, were carried out. From the kinetic curves collected under different conditions of reactants concentration, addition of bromide ions, temperature, pH and ionic strength, corresponding rate constants have been determined. The obtained results suggest the complex path of the [AuBr4]– reduction consisting of two parallel, bimolecular reactions where different reductant species (HNO2 and NO2–) take place and consecutive step with the metallic gold production. The second-order rate constants at 20oC are equal to 2.948 and 0.191 M–1·s–1, respectively. The values of activation enthalpy and activation entropy for the first and the second parallel step of the reaction were found to be ΔH‡ = 29.18 kJ·mol–1 and ΔS‡ = –13.95 J·mol–1·K, and ΔH‡ = 40.75 kJ·mol–1 and ΔS‡ = –31.06 J·mol–1·K, respectively. It was found that the reaction accelerates significantly with the increase of pH and is inhibited with the increase of Br– concentration. The substitutive, inner-sphere mechanism of electron transfer in the studied system was also suggested.
The use of lactoferrin (LF) and/or lactobacillus sp. (LB) to improve animal health and production has increased recently. However, information regarding the immune-modulatory role of LB supplementations either alone or in combination with LF in sheep remains unclear. Therefore, the present study was designed to evaluate the immune modulating properties and the antioxidant activity of supplementing commercially available LF and/or LB in healthy lambs. For this reason, twenty-four apparently healthy Ossimi lambs were used. After three weeks of acclimatization, the lambs were randomly allocated to four equal-sized groups and assigned to receive one of the following supplements: LB at a dose of ~ 1 g active ingredient/head (group 1), LF at a dose rate of 0.5 gm /head (group 2), a combination of both treatments using the same dosing regimens (group 3), and (group 4) received only 10 mL of isotonic saline and was considered as a control group. All supplements were given orally twice daily for 30 consecutive days. Blood samples were collected from each lamb before starting the experiment (T0) and two weeks (T15), and four weeks (T30) after giving supplements for hematological examinations, serum biochemical analyses, and RT-PCR assays. Our findings demonstrated that lambs receiving LB showed statistically significant (P<0.05) higher values of total leucocytes, lymphocytes and lysozyme activity than those receiving LF. In contrast, lambs that received LF had significantly (P< 0.05) higher values of serum catalase, nitric oxide and GSH with a significantly lower MDA level compared with those supplemented with LB. A combination of LF and LB supplementation elicited maximal up-regulation of Tollip, TLR4, IL-5, and IL-6 gene expression compared with other groups. The results suggest that bovine LF and or LB could be used as useful nutritional supplements to support the immune system in healthy lambs.