Szocs K, Gabor F, Csik G, Fidy J
Institute of Biophysics, Semmelweis University of Medicine, Budapest, Hungary.
J Photochem Photobiol B. 1999 May;50(1):8-17. doi: 10.1016/S1011-1344(99)00062-7.
The possibility and conditions for the induction of porphyrin synthesis by exogenous delta-aminolaevulinic acid (ALA) and its applicability for the inactivation of Gram-negative bacteria Escherichia coli B. by photodynamic therapy (PDT) have been studied. The bacteria are supplemented with ALA in the log phase of growth, and are grown in a synthetic medium at 37 degrees C in the dark. The efficiency of porphyrin synthesis is detected by fluorescence spectroscopy performed on the isolated bacterial cells and the medium, respectively, and compared with results of high-performance liquid chromatography (HPLC) analysis. ALA stimulates the synthesis of protoporphyrin in the bacteria by a factor of five to six, and an increased amount of the more hydrophilic derivatives with a significant contribution of mesoporphyrin by a factor of two to three is observed in the culturing medium. The optimal conditions of ALA treatment with respect to PDT are 10-15 min of incubation of a bacterial culture of 2 x 10(7) cells ml-1 with (5-9) x 10(-3) mol l-1 ALA. The ALA-treated cells are irradiated by white light of 80 mW cm-2 under growth conditions and a decrease to 0.6% of the number of colony-forming units (CFUs ml-1) is observed after 90 min of irradiation.
研究了外源性δ-氨基乙酰丙酸（ALA）诱导卟啉合成的可能性和条件，以及其在光动力疗法（PDT）灭活革兰氏阴性菌大肠杆菌B中的适用性。在细菌生长的对数期向其补充ALA，并使其在37℃的合成培养基中于黑暗中生长。分别通过对分离出的细菌细胞和培养基进行荧光光谱检测卟啉合成效率，并与高效液相色谱（HPLC）分析结果进行比较。ALA可使细菌中原卟啉的合成增加5至6倍，并且在培养基中观察到亲水性更强的衍生物（中卟啉有显著贡献）的量增加了2至3倍。关于PDT，ALA处理的最佳条件是将2×10⁷个细胞/毫升的细菌培养物与（5 - 9）×10⁻³摩尔/升的ALA孵育10 - 15分钟。在生长条件下，用80毫瓦/平方厘米的白光照射经ALA处理的细胞，照射90分钟后观察到菌落形成单位（CFU/毫升）数量减少至0.6%。
