迷迭香水提液及迷迭香酸对大肠杆菌感染小鼠保护作用研究OA

This study aimed to investigate the in vitro antibacterial activity of rosemary aqueous extract and its active component,rosmarinic acid,against Escherichia coli,as well as their protective effects on intestinal damage in infected mice.Rosemary aqueous extract was prepared using the hot water reflux extraction method.The in vitro antibacterial activity was evaluated using the Oxford cup assay and the micro-broth dilution method,and the minimum inhibitory concentration(MIC)was determined.A mouse model of Escherichia coli infection was established to observe the effects of pretreatment with the rosemary aqueous extract or rosmarinic acid on the survival rate,body weight,intestinal function,organ pathology,and serum biochemical indices of infected mice.The results showed that the rosmarinic acid content in the rosemary aqueous extract was 6.73 mg/g.Rosemary aqueous extract at 1.00 g/mL and 0.50 g/mL exhibited moderate sensitivity against Escherichia coli,while 0.25 g/mL rosemary aqueous extract and 1.0～4.0 g/L rosmarinic acid showed low sensitivity.The MIC of rosemary aqueous extract and rosmarinic acid were 0.250 00 g/mL and 4.000 00 g/L respectively.The rosemary aqueous extract demonstrated dose-dependent antibacterial activity within 12 hours.In vivo experiments revealed that pretreatment with rosemary aqueous extract(0.25 g/kg and 0.50 g/kg)or rosmarinic acid(3.365 mg/kg)improved the survival rate and alleviated weight loss in infected mice.The 0.50 g/kg rosemary aqueous extract ameliorated intestinal hypermotility,reduced organ damage and intestinal histopathological alterations,and reduced serum inflammatory factor content and transaminase activity.The study shows that rosemary aqueous extract and rosmarinic acid exhibit inhibitory effects against Escherichia coli and mitigate infection-induced intestinal damage,demonstrating potential as green feed additives for the prevention and control of Escherichia coli infections in livestock and poultry.