悬铃木叶片暗棕色抑菌化合物的稳定性及其活性

从悬铃木叶片中提取的暗棕色抑菌化合物在生理盐水中的吸收光谱与用相同方法从樟树叶片中提取的抑菌化合物的吸收光谱相类似；抑菌化合物分别在pH4.0-8.0的0.16mol/L Na^ 盐溶液和含5％的葡萄糖溶液中对光热稳定，在pH3.5以下容易析出；在柠檬酸、磷酸及Tris-HCl等常用的缓冲溶液系统中，在pH4.0-8.0范围内也稳定；10mmol/L的F3^3 、Cu^2 、Ca^2 、Mg^2 、Zn^2 等两价金属离子，在生理pH条件下，对抑菌化合物的稳定性没有影响；抑菌化合物和常用的LB培养基先混合后再灭菌的抑菌活性与分别灭菌后再混合的抑菌活性没有明显差异，其抑菌活性的强弱为：金黄色葡萄球菌＞枯草杆菌＞巨大芽孢杆菌＞大肠杆菌＞苏云金杆菌。

Stability and Activity of Anti-microbial Dark Brown Compound from Leaves of Platanus orientalis

The anti-microbial dark brown compound isolated from the leaves of Platanus orientalis has high stability in solutions of 0.16 mol/L NaCl and 5% glucose with pH4.0～8.0, and precipitates in the solutios with pH below 3.5. It is also stable when the compound is resolved in buffers of citrate, phosphate and Tris-HCl, and in the solutions containing 10 mmol/L Fe3＋,Cu\+\{2+\},Ca2＋,Mg\+\{2+\} and Zn\+\{2+\} ions with pH7.0 respectively. Moreover, there is no difference of anti-microbial activities of the antimicrobial dark brown compound whether it is sterilized with LB culture medium or sterilized separately before used. The sensitivities of different bacteria to the antimicrobial dark brown compound with the different sterilized treatments are Staphylococcus aureaus>Bacillus subtilis>Bacillus megatherium>Escherichia coli>Bacillus thuringiensis.