中文摘要：

采用琼脂扩散法和微量二倍稀释法检测桑树活性单体化合物桑根皮素对金黄色葡萄球菌、枯草芽孢杆菌、大肠杆菌、沙门氏菌、普通变形杆菌等5种常见食源性致病菌的抑制作用，探究热处理、紫外线照射、介质pH值、氧化剂和还原剂对桑根皮素抑菌活性的影响。桑根皮素对5种测试菌株的抑制作用强弱不一，对枯草芽孢杆菌和金黄色葡萄球菌2种革兰阳性菌（G＋）的抑制效果明显，其中对枯草芽孢杆菌的抑制活性最强，最低抑菌浓度（MIC）〈1．56μg/mL；而对沙门氏菌、普通变形杆菌和大肠杆菌3种革兰阴性菌（G-）的抑制活性较弱。紫外线照射或热处理温度〈100℃时对桑根皮素的抑菌活性没有明显影响，但热处理温度〉100℃使桑根皮素的抑菌活性明显减弱；在pH6—9范围内，桑根皮素的抑菌活性随着介质pH值增大有所减弱；随着还原剂（Na2SO3）的浓度增大，桑根皮素对金黄色葡萄球菌的抑制活性逐渐减弱，而氧化剂（H2O2）的浓度对其抑菌活性影响较小。研究结果提示桑根皮素是桑树中具有抑菌作用的重要物质之一，高温（〉100℃）、强碱性环境及高浓度还原剂对桑根皮素的抑菌活性有影响。

英文摘要：

In this study, inhibitory effects of morusin from mulberry （Morus L. ） against 5 common food-borne pathogenic bacteria, namely Staphyloccocus aureus, Bacillus subtilis, Escherichia coil, Salmonella spp. and Proteus vulgaris, were tested by agar diffusion method and microscale double dilution method. Meanwhile, the effects of thermal treatment, ultraviolet illumination, medium pH value, oxidant and reducer on the antibacterial activity of morusin were also investigated. The results indicated that inhibitory effects of morusin against the 5 tested bacterial strains were different. The two Gram-positive bacteria （ G ＋ ）, Bacillus subtilis and Staphylococcus aureus, were remarkably inhibited. Morusin had the highest antibacterial activity against Bacillus subtilis, with the minimum inhibitory concentration （MIC） below 1.56μg/mL. Its inhibition to the three Gram-negative bacteria （ G - ）, Salmonella spp., P. vulgaris and E. coli, was relatively weak. Ultraviolet illumination and thermal treatment below 100 ℃ had no obvious influence on the antibacterial activity of morusin. After thermal treatment of above 100 ℃, the antibacterial activity of morusin decreased obviously, Within pH 6 -9 range, the antibacterial activity of morusin decreased with increase of medium pH value. When the concentration of reducer Na2SO3 was increased, the antibacterial activity of morusin to Staphylococcus aureus declined gradually. The concentration of oxidant H2 Q2 had little influence on the antibacterial activity of morusin. These results suggest that morusin is one of the important substances of mulberry with antibacterial activity. High temperature （above 100 ℃）, strong alkaline and high concentration reducer had influence on the antibacterial activity of morusin.