呫吨化合物对大肠埃希菌和金葡菌的光敏抗菌活性研究

The photobactericidal activity of xanthene derivatives against Escherichia coli and Staphylococcus aureus

目的测定六种呫吨(xanthene)化合物的光敏抗菌活性以及它们的物理化学性质,评价两者之间的联系.方法通过测量最低致死浓度(MLC)和Daniel抑菌圈法测定六种呫吨化合物的光敏抗菌活性;采用对-亚硝基二甲基苯胺(RNO)脱色反应检测单线态氧产率.结果有光无光条件下,除Na2Fl外的其余五种化合物均表现出不同水平的抗菌性能.无光条件下,五种呫吨化合物对测试菌固有毒性基本相同;光照条件下,五种化合物则显示出较强的光敏毒性,化合物对大肠埃希菌的MLC值为250～125μmol/L,对金葡菌的MLC为31.3～lμmol/L;对同种菌的光敏毒性强度与化合物的单线态氧的产率基本一致.结论呫吨化合物对大肠埃希菌及金葡菌均表现出较强的光敏毒性,呫吨化合物的固有毒性主要取决于化合物分子的母核结构,取代基团对其影响较小.随着卤代原子的增加,单线态氧的产率增加,光敏活性加强;金葡菌对呫吨化合物较大肠埃希菌更为敏感.

Objective To investigate the physicochemical properties of six xanthene derivatives and their photobactericidal activity against Escherichia coli and Staphylococcus aureus, and find the relationship between them. Methods The photobactericidal activity of six xanthene derivatives against E. coli and S. aureus was determined by agar dilution method and the modified methods of Daniels; singlet oxygen yields were measured by monitoring the bleaching of p-nitrosodimethylaniline. Results Na2F1 showed no inherent toxici- ty and photoxicity in experiments. Without illumination, the staining agents except Na2F1 almost showed the same level of inherent toxicity to either E. coli or S. aureus. Upon illumination, the photosensitizers except Na2F1 showed more apparent phototoxicity to all organisms with an minimum lethal concentration （MLC） of 250μmol/L - 125μmol/L against E. coli and an MLC of 31.3μmol/L- 1μmol/L against S. aureus. In vitro chemical test showed that each of the xanthene derivatives was able to photosensitize the production of singlet oxygen corresponding to their photobactericidal activity. Conclusions In general the staining agents tested here showed different phototoxicity to E. coli and S. aureus. The inherent toxicity of staining agents was most dependent on the structure of parent nucleus, and substituting groups had slight effects on the inherent activity. With the increasing of the number of the halogen substituents, the singlet oxygen yields increased, and the phototoxic activity increased too. The staining agents examined showed stronger effects in their phototoxicity to S. aureus compared with that of E. coli.