Valentina Pavić

Effects of organic selenium supplemented to layer diet on table egg freshness and selenium content

Abstract The aim of the research was to determine the effects that organic selenium supplemented in layer diets has on its content in the edible part of egg, on egg freshness and activity of glutathione peroxidase (GSH-Px) in hens’ blood. The experiment lasted for 30 days and was completed on 240 laying hens of the Hy Line Brown hybrid. Hens were divided into 2 experimental groups (E1 and E2), each consisting of 120 hens housed in 24 cages. Hens were fed a commercial diet containing 18% of crude protein and 11.60MJ ME/kg. The experiment was set up in two different feeding treatments. The E1 group had diets supplemented with 0.2ppm of selenium, and E2 had diets with 0.4ppm of selenium (organic selenium Sel-Plex®, Alltech, inc.). The GSH-Px activity was higher in blood of hens in the E2 group than in the E1 (P<0.05). Furthermore, statistically the E2 group had a significantly higher portion of selenium in egg yolks and albumen than the E1 group (P<0.05). Analysis of effects that feeding treatments have on egg freshness over three examined periods (fresh eggs, eggs stored for 14 and for 28 days at 4ºC) showed better results for HU (Haugh units) and TBARS (thiobarbituric acid reactive substances) in the E2 eggs than in the E1 eggs.

Design and Synthesis of Some New 1,3,4-Thiadiazines with Coumarin Moieties and Their Antioxidative and Antifungal Activity

A series of newly disubstituted (compounds 4a,b) and trisubstituted 1,3,4-thiadiazines 5a–l with various substituents was prepared utilizing different thiosemicarbazides and 3-α-bromoacetylcoumarins as starting compounds. The structures of the synthesized 1,3,4-thiadiazines are elucidated and confirmed utilizing the corresponding analytical and spectroscopic data. All of the new thiadiazine derivatives were tested for their antioxidant activity, employing different antioxidant assays (DPPH scavenging activity, iron chelating activity, power reducing activity). Compounds 5b, 5f, 5j and 4b were proven to be the best DPPH radical scavengers, while compounds 5h and 5j have shown the best iron chelating activity. Thiadiazine derivatives were also tested on their antifungal activity against four mycotoxicogenic fungi, Aspergillus flavus, A. ochraceus, Fusarium graminearum and F. verticillioides. The best antifungal against A. flavus was proven to be compound 5e, while compounds 4a and 5c were the best antifungals on A. ochraceus, and compound 5g showed the best antifungal activity on F. verticillioides.

Mono- and bis-dipicolinic acid heterocyclic derivatives – thiosemicarbazides, triazoles, oxadiazoles and thiazolidinones as antifungal and antioxidant agents

Abstract A series of dipicolinic acid derivatives was synthesized and investigated for antimicrobial and antioxidant activity. Mono and bis derivatives of ethyl dipicolinate were utilized as starting materials for synthesis of mono- and bis-hydrazides. Thiosemicarbazides were obtained by reaction of hydrazides with isothiocyanates and cyclized into triazoles, thiadiazoles, oxadiazoles and thiazolidinones. Some of these products, especially those incorporating a thiazolidinone moiety in their structure, are excellent antioxidants, DPPH scavengers and antifungal agents.

Environmentally Friendly Approach to Knoevenagel Condensation of Rhodanine in Choline Chloride: Urea Deep Eutectic Solvent and QSAR Studies on Their Antioxidant Activity

A series of rhodanine derivatives was synthesized in the Knoevenagel condensation of rhodanine and different aldehydes using choline chloride:urea (1:2) deep eutectic solvent. This environmentally friendly and catalyst free approach was very effective in the condensation of rhodanine with commercially available aldehydes, as well as the ones synthesized in our laboratory. All rhodanine derivatives were subjected to 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) scavenging activity investigation and quantitative structure-activity relationship (QSAR) studies were performed to elucidate their structure-activity relationship. The best multiple linear QSAR model demonstrate a stability in the internal validation and Y-randomization (R2 = 0.81; F = 24.225; Q2loo = 0.72; R2Yscr = 0.148). Sphericity of the molecule, ratio of symmetric atoms enhanced atomic mass along the principle axes in regard to total number of atoms in molecule, and 3D distribution of the atoms higher electronegativity (O, N, and S) in molecules are important characteristic for antioxidant ability of rhodanine derivatives. Molecular docking studies were carried out in order to explain in silico antioxidant studies, a specific protein tyrosine kinase (2HCK). The binding interactions of the most active compound have shown strong hydrogen bonding and van der Waals interactions with the target protein.