Studies on the Influence of Photosensitizing Dyes on Microorganisms Part Ⅰ. Study on the Antimicrobial Activity of Photosensitizing Dyes

The author studied the antimicrobial activity of photosensitizing dyes as food preservatives, and obtained the following results: 1) Antimicrobial activities of photosensitizing dyes to various sorts of microorganisms are in parallel with each other. 2) The following are the photosensitizing dyes which showed a relatively high antimicrobial activity to all the tested organisms: four kinds of monomethine cyanine, NK 266 (4.4'-dimethyl-3.3'-dihepthyl-2.2'-monomethine thiazolocyanine-3-iodide), NK 400 (4.4'-dimethyl-3.3'-diocthyl-2.2'-monomethine thiazolocyanine-3-iodide), NK 564 (4.4'-dimethyl-3.3'-dihepthyl-2.2'-monomethine thiazolocyanine-3-chloride), NK 570 (4.4'-dimethyl-3.3'-diocthyl-2.2'-monomethine thiazolocyanine-3-acetate); a kind of mesochlor pentamethine cyanine, NK 74 (3.3'-diethyl-10-chlor-2.2'-pentamethine thiocyanine-3-iodide); a kind of styryl type dye, NK 573 (2.6. bis (p-dimethylaminostyryl) pyridine-1-methylacetate). 3) Many photesensitizing dyes were proved to be of use as food preservatives. For the practical use, however, further tests on the toxicity and trial application to foods are necessary.