Instituto de Ciências Agrárias, 28114Universidade Federal de Minas Gerais, Montes Claros, Brazil.
Escola de Veterinária, 28114Universidade Federal de Minas Gerais, Belo Horizonte, Brazil.
Food Sci Technol Int. 2020 Jan;26(1):11-20. doi: 10.1177/1082013219858529. Epub 2019 Aug 1.
Human ingestion of antimicrobial residues in dairy products is a problem of public health. In this study we evaluated antibacterial effectiveness of aqueous and ethanolic leaf extracts of L. as a natural alternative for reduction of spp. biofilms. Eight spp. strains from cows with mastitis and the strain (ATCC 25923) were evaluated. High performance liquid chromatography indicated the presence of phenolic compounds in the aqueous extract. Agilent Technologies gas chromatography revealed the presence of phenolic compounds, carbohydrates, and gallic acid in ethanolic extract. The tannin contents were 2.27 ± 0.01 and 2.67 ± 0.01% for ethanolic extract and aqueous extract, respectively. Extracts were evaluated in agar diffusion test and the size of inhibition zones were compared. The ethanolic extract was the most effective, showing minimum inhibitory concentrations and minimum bactericidal concentrations between 1.8-7.5 and 15.1-45.3 mg/ml, respectively. After tannin removal, the extracts were less effective, indicating these secondary metabolites as one of the main antibacterial compounds. The ethanolic extract at 45.3 mg/ml reduced mature biofilms in teat rubber (average: 3.91 log reduction) and stainless steel (average: 3.87 log reduction) after 5 min of contact. The extracts of leaves represent natural alternatives against spp. strains and the ethanolic extract shows potential as a natural sanitizer.
人摄入奶制品中的抗菌残留是一个公共卫生问题。在这项研究中，我们评估了作为减少 spp.生物膜的天然替代品的 L.叶的水提物和醇提物的抗菌效果。从乳腺炎奶牛中分离出 8 株 spp.菌株和 株（ATCC 25923）进行了评估。高效液相色谱法表明水提物中存在酚类化合物。安捷伦气相色谱法显示醇提物中存在酚类化合物、碳水化合物和没食子酸。单宁含量分别为 2.27±0.01%和 2.67±0.01%。提取物在琼脂扩散试验中进行了评估，并比较了抑菌圈的大小。醇提物最有效，最小抑菌浓度和最小杀菌浓度分别为 1.8-7.5 和 15.1-45.3mg/ml。单宁去除后，提取物的效果降低，表明这些次生代谢物是主要的抗菌化合物之一。醇提物在 45.3mg/ml 时，接触 5 分钟后可减少乳头橡胶（平均减少 3.91 个对数）和不锈钢（平均减少 3.87 个对数）上成熟的生物膜。 L.叶的提取物是针对 spp.菌株的天然替代品，醇提物具有作为天然消毒剂的潜力。
