Eucalyptus viminalis leaf extract alters the productivity and blood parameters of healthy broiler chickens.

BACKGROUND AND AIM: As an alternative to natural and chemically synthesized direct-acting bactericides, there has been an increase in the use of plant extracts, which possess a set of phytochemicals with potential for microbial disease control; this is due to the spectrum of secondary metabolites present in extracts, which include phenolic compounds, quinones, flavonoids, alkaloids, terpenoids, and polyacetylenes. The biologically active substances within plant extracts, which perform protective functions for plant tissues, can have ambiguous effects on the animal body. Therefore, the aim of this study was to assess the ability of gamma-octalactone, isolated from Eucalyptus viminalis extract, to inhibit various LuxI/LuxR quorum-sensing (QS) systems in bacteria, and to evaluate its effect on broiler chickens. MATERIALS AND METHODS: Phytochemical analysis of E. viminalis extract was performed. The ability of gamma-octalactone to inhibit QS was evaluated using four different LuxI/LuxR bacterial test systems. In vivo assessments were performed on one hundred and twenty 7-day-old broiler chickens (Arbor Acres cross), split into four groups of 30 chickens: 1. Control group: Basic diet (BD); 2. experimental Group I: BD + gamma-octalactone at a dosage of 0.05 ml/kg live weight/day; 3. experimental Group II: BD + gamma-octalactone at a dosage of 0.1 ml/kg live weight/day; and 4. experimental Group III: BD + gamma-octalactone at a dosage of 0.2 ml/kg live weight/day. Hematological blood parameters were assessed using an automatic hematological analyzer (URIT-2900 Vet Plus, URIT Medial Electronic Co., China) and an automatic biochemical analyzer (CS-T240, Dirui Industrial Co., Ltd., China). Statistical analyses were performed using SPSS Statistics Version 20 (IBM); averages (M), standard deviations (σ), and standard deviation errors (m) were calculated. Results with p≤0.05 were considered significant. RESULTS: Based on the phytochemical analysis results, libraries of compounds with putative QS inhibitory properties were compiled. Gamma-octalactone exhibited a pronounced inhibitory effect on the LuxI/LuxR QS systems, characterized by EC50 values of 0.15-0.4 mM. In the in vivo portion of this study, broiler chicken live weights increased in all experimental groups, with the most significant increase in Group III (14.0%), in relation to the control group. Blood serum from the experimental group chickens had significantly higher levels of triglycerides and uric acid (p≤0.05), in comparison to the control group chickens. With respect to blood serum enzyme activity and antioxidant status indicators, the experimental group chickens had a higher level of gamma-glutamyl transferase, an enzyme associated with amino acid metabolism, than those in the control group; this increase was especially pronounced in Group III, with 37.0% increase (p≤0.05). Superoxide dismutase and catalase levels were higher in the experimental groups than the control group, corresponding to increases of 30.4-56.2% (p≤0.05), 33.3-83.3%, and 27.9-45.5% (p≤0.05) in Groups I, II, and III (p≤0.05), respectively. Morphological blood parameters did not display significant changes due to gamma-octalactone. CONCLUSION: According to the results of this in vivo study in broiler chickens, gamma-octalactone, isolated from E. viminalis leaf extract and supplied at a dosage of 0.2 ml/kg live weight/day, led to an increase in the activity of blood plasma digestive enzymes, increased live weight, and had a positive effect on lipid metabolism and antioxidant status.

Effect of the combined action of Quercus cortex extract and probiotic substances on the immunity and productivity of broiler chickens.

AIM: This study was designed to investigate the synergistic effect of the combined action of probiotic bacterial strains (Bifidobacterium adolescentis and Lactobacillus acidophilus) and Quercus cortex extract as biologically active substances in the feed on the immunity and productivity of Gallus gallus domesticus. MATERIALS AND METHODS: For the experiment, 120 7-day-old broiler chickens were selected (4 groups, n=30, 3 replicates with 10 birds in each group). The groups were as follows: The reference group - basic diet (BD); experimental Group I - BD + Q. cortex extract (Q. cortex), 2.5 ml/kg of body weight; experimental Group II - BD + probiotic preparation based on B. adolescentis, 80.0 million colony-forming units (CFU), and L. acidophilus, 1.0 million CFU (dosage in accordance with the recommendations of the manufacturer); and experimental Group III - BD + probiotic + extract of Q. cortex. The following methods of study were used: Chemiluminescence and biochemical and hematological analysis. RESULTS: The results of the experiment showed a slight decrease in the level of leukocytes in Groups II (p≤0.05) and III, and of hemoglobin in Group III (p≤0.05), compared to the reference group. The level of alanine aminotransferase and aspartate aminotransferase in Group II was higher than both the reference group (p≤0.05) and the other groups. Introduction of Q. cortex extract into the diet increased the level of triglycerides (p≤0.05) and urea in the blood serum. The combined use of probiotic preparations and the extract resulted in an increase in the level of iron in the blood serum by 78.1% (p≤0.05) in Group III. An increase in indicators of the antioxidant system (catalase increased in Group I by 27.2% (p≤0.05) and by 3.0-12.7% in other groups; superoxide dismutase increased by 3.0-13.2%) and nonspecific immunity (ß-lysine increased by 8.8-16.0%) was noted. Introduction of the extract and probiotic preparation into the diet contributed to increasing the live weight of chickens at the age of 15 days by 5.9 and 7.4%, respectively (p≤0.05). In experimental Group II, this trend continued, and by the end of the period, the weight of animals exceeded that of their peers in other groups by 0.7-7.0%. Given the high preservation rate of poultry in the II and III Groups, and the low feed consumption per 1 kg of live weight gain (by 3.1-6.7%), the efficiency of growth was higher than in the reference group. CONCLUSION: Thus, the combined use of probiotic strains of bacteria and Q. cortex extract helped to increase the antioxidant activity of the organism and antimicrobial components of blood plasma compared with broiler chickens with similar growth rates but without the supplementation of this combination.

Antimicrobial activity of the indolicidin-derived novel synthetic peptide In-58.

Natural peptides with antimicrobial activity are extremely diverse, and peptide synthesis technologies make it possible to significantly improve their properties for specific tasks. Here, we investigate the biological properties of the natural peptide indolicidin and the indolicidin-derived novel synthetic peptide In-58. In-58 was generated by replacing all tryptophan residues on phenylalanine in D-configuration; the α-amino group in the main chain also was modified by unsaturated fatty acid. Compared with indolicidin, In-58 is more bactericidal, more resistant to proteinase K, and less toxic to mammalian cells. Using molecular physics approaches, we characterized the action of In-58 on bacterial cells at the cellular level. Also, we have found that studied peptides damage bacterial membranes. Using the Escherichia coli luminescent biosensor strain MG1655 (pcolD'::lux), we investigated the action of indolicidin and In-58 at the subcellular level. At subinhibitory concentrations, indolicidin and In-58 induced an SOS response. Our data suggest that indolicidin damages the DNA, but bacterial membrane perturbation is its principal mode of action. Copyright © 2017 European Peptide Society and John Wiley & Sons, Ltd.