RESUMO
BACKGROUND AND OBJECTIVES: Antimicrobial peptides produced by lactic acid bacteria have gained enormous attention owing to their health benefits. This study aimed to isolate, purify and characterize the antibacterial protein produced by autochthonous Lactobacillus casei TA0021 strain. MATERIALS AND METHODS: The antagonistic activity of L. casei TA0021 against a number of pathogenic bacteria was tested by agar well diffusion assay. The antimicrobial agent in the neutralized supernatant fluids was subjected to the action of proteolytic enzymes, catalase, lipase and lysozyme, and their tolerance to variable pH and temperature was estimated. The proteinaceous antagonistic compound was precipitated by 60% w/v ammonium sulphate, desalted and subjected to cation exchange and gel filtration chromatography. Approximate molecular weight of Lactocin was determined by SDS-PAGE and non-denaturing gel electrophoresis. Hemoglobin release assay and cytotoxicity effect of Lactocin TA0021 was determined. The results were statistically analyzed. RESULTS: The antagonistic agent active against Salmonella Typhimurium and Shigella flexneri appeared resistant to catalase and lipase treatments, while sensitive to the tested proteolytic enzymes. Lactocin TA0021 resisted acidic pH values of 3.0, while alkaline pH values of >9 completely destroyed the activity. The antibacterial peptide was approximately 68 KDa and heat labile as lost its activity at 100°C after 5 minutes. The bacteriocin was non-toxic to MRC-5 cell lines and non-hemolytic. Purification method lead to increase in antibacterial activity while, subsequent decrease in recovery and yield was observed with increasing purification fold. CONCLUSION: The purified antimicrobial protein from L. casei TA0021 might be used for application in medicinal and food products.
RESUMO
INTRODUCTION: Medicinal plants are increasingly used in the treatment of cardiovascular diseases due to their multifaceted properties. This study was designed to investigate anti-arrhythmic and anti-inflammatory potentials of the natural bioflavonoid, troxerutin (TXR) in myocardial ischemia/reperfusion (I/R) injury in diabetic rats. METHODS: Male Wistar rats were randomly divided into 4 groups (control, controlâ¯+â¯TXR [150â¯mg/kg, daily], diabetic, and diabeticâ¯+â¯TXR). Type-1 diabetes was induced by an intraperitoneal injection of streptozotocin (50â¯mg/kg) and lasted for 10 weeks. After mounting on the Langendorff apparatus, isolated hearts in all groups received a normal Krebs-Henseleit solution for 20â¯min of stabilization period, followed by 30â¯min of regional ischemia through ligation of the left anterior descending coronary artery, and 60â¯min of full reperfusion. During the experiment, the electrocardiograms were recorded and the arrhythmias [number, duration and incidence of premature ventricular complexes (PVC), ventricular tachycardia (VT), ventricular fibrillation (VF), and arrhythmia score] during I/R phases were assessed based on the Lambeth Convention. Ischemic left ventricular samples were used to determine the activities of lactate dehydrogenase (LDH), interleukin-1beta (IL-1ß), and tumor necrosis factor (TNF-α). RESULTS: The arrhythmias induced by I/R were not significantly changed in diabetic group as compared to the control group. However, pretreatment with TXR significantly reduced the number of PVC and duration and incidence of VF in ischemic phase in comparison to the untreated animals (Pâ¯<â¯0.05). In addition, the duration, and incidence of most arrhythmias during reperfusion phase were significantly declined by TXR administration in both control and diabetic groups (Pâ¯<â¯0.05). Pretreatment of rats with TXR significantly reduced myocardial inflammatory cytokines TNF-α and IL-1ß levels after I/R insult in diabetic as well as control hearts (Pâ¯<â¯0.05). CONCLUSION: Preconditioning with TXR could provide cardioprotection by anti-arrhythmic and anti-inflammatory effects against I/R injury in rat hearts. This effect of TXR can introduce this material as a protective agent in cardiovascular diseases.
