##STR1## The invention relates to compounds represented by formula (I) and their salts: wherein R.sup.1 represents hydrogen, lower alkyl, halogen, cyano, or lower alkyloxycarbonyl, R.sup.2 and R.sup.3 each represents hydrogen, lower alkyl, C.sub.3 -C.sub.7 cycloalkyl, or aryl, or taken together may form piperazino or morpholino together with the adjacent nitrogen atom. These compounds scarcely emit fluorescence when present alone in an aqueous solution but, in the presence of a protein such as .alpha..sub.1 -AG, they bind to the protein to emit strong fluorescence, thus being suitable reagents for determining proteins existing in a minute amount in blood, particularly .alpha..sub.1 -AG.
本发明涉及由式(I)表示的化合物及其盐:其中,R.sup.1表示氢、低级烷基、卤素、
氰或低级烷氧羰基,R.sup.2和R.sup.3分别表示氢、低级烷基、C.sub.3-C.sub.7环烷基或芳基,或者与相邻的氮原子一起形成
哌嗪基或吗啉基。这些化合物在
水溶液中单独存在时几乎不发射荧光,但在存在蛋白质(如α1-AG)的情况下,它们与蛋白质结合后会发出强烈的荧光,因此适用于测定血液中存在微量的蛋白质,特别是α1-AG的试剂。