草豆蔻有效部位对奶牛乳腺炎病原菌的抗菌活性研究

Antibacterial activity of Alpinia katsumadai Hayata against bacteria from milk of dairy cows suffering with mastitis

采用琼脂平板2倍稀释法测定了草豆蔻水提物、醇提物、醇-水提取物、挥发油4个活性部位对15个不同种属120株奶牛乳腺炎病原菌的最低抑菌浓度,用SPSS17.0软件中单因素方差分析法比较分析了4个活性部位分别对金黄色葡萄球菌、鲁氏不动杆菌和芽孢杆菌等11种菌株的抑菌活性的强弱;采用小鼠全身感染模型分析了草豆蔻油对金黄色葡萄球菌和大肠杆菌的体内抗菌活性。结果显示,草豆蔻4个活性部位对受试菌有不同程度的体外抗菌活性,且对革兰氏阳性菌的抗菌活性较对革兰氏阴性菌的活性强;在4个活性部位中,以挥发油的体外抗菌活性最强,除对4株单胞菌和7株大肠杆菌无抑菌活性外,对其余109株受试菌均有较强的活性,对革兰氏阳性菌的MIC50和MIC90分别为0.94～1.87mg/mL和0.47～1.87mg/mL,对革兰氏阴性菌的MIC50和MIC90均为0.47～29.92mg/mL。草豆蔻油在体内对金黄色葡萄球菌感染模型小鼠和大肠杆菌感染模型小鼠有强的保护作用。高、中、低3个剂量对金黄色葡萄球菌感染模型小鼠的保护率分别为100%、90%、80%,对大肠杆菌感染模型小鼠的保护率分别为100%、90%、40%,呈明显量效关系。结果表明,草豆蔻挥发油是中药草豆蔻对奶牛乳腺炎病原菌的抗菌活性物质,可用于奶牛乳腺炎等感染性疾病的防治和食品防腐剂的开发。

The minimum inhibitory concentrations（MICs） of water extract,ethanol extract,ethanol-water extract and essential oil from Alpinia katsumadai Hayata against 120 isolates from milk produced by dairy cow with mastitis were determined by agar dilution method.The data were analyzed using statistical software SPSS 17.0,and the multifactor analysis of variance（ANOVA） was used to compare the 4 active fractions of Alpinia katsumadai Hayata against different bacterial species.In vivo efficacy of essential oil against mouse systemic infections was evaluated with one isolate of S.aureus or E.coli,respectively.In result,the 4 extracted fractions of Alpinia katsumadai Hayata showed different antibacterial activity to different species of experimental bacteria,and they had higher activity against Gram-positive than Gram-negative isolates.The oil had the highest activity against 109 strains of Gram-positive and Gram-negative isolates among the 4 fractions,with MIC50 and MIC90 ranging from 0.94 to 1.87 mg/mL and from 0.47 to 1.87mg / mL against Gram-positive isolates,from 0.47to 29.92mg / mL and from 0.47to 29.92mg / mL against Gram-negative isolates,respectively.The oil also showed strong efficacy in mouse peritonitis model infected with S.aureus or E.coli.Their actions were dose-dependent.In conclusion,antibacterial substance of Alpinia katsumadai Hayata was its oil,which had broad-spectrum antibacterial activity which make it a potential candidate as antibacterial agent to treat infectious diseases and alternative substance to preserve food.