Abstract: Novel pheophorbide derivatives of the general formula: ##STR1## [wherein Z is O or NH; n is an integer of 1 to 6; Y is NR'R" or ##STR2## wherein R', R" and R'" are the same or different or each represents a C.sub.1 to C.sub.4 lower alkyl group; X.sup.- is a halogen or organic acid ion); R.sub.1 is an ethenyl group; C.sub.1 to C.sub.4 lower alkyl group or ##STR3## (wherein m is an integer of 0 to 6; R.sub.6 is H or a C.sub.1 to C.sub.4 lower alkyl group); R.sub.2 is CH.sub.3, CHO or CH.sub.2 OH; either of R.sub.3 and R.sub.4 is H, with the other being OH, or both of them combine to represent .dbd.O; R.sub.5 is H or CO.sub.2 CH.sub.3) are provided.When administered to a cancer-carrying animal, the derivatives accumulate specifically in cancer tissues and emit characteristic fluorescent spectrum under irradiation of light, which enables one to detect the cancer tissues.

Abstract: Novel porphyrin derivatives of the general formula: ##STR1## wherein R.sub.1 each independently denotes a hydrogen, a C.sub.1 -C.sub.4 alkyl group or an ethenyl group, and R.sub.2 each independently denotes COZ(C.sub.m H.sub.2m)Q, COZCH(C.sub.m H.sub.2m Q).sub.2, --CH.sub.2 --Q [wherein Z is O, S or NH, m is an integer of 1 to 23, and Q is a di-(C.sub.1 -C.sub.4 alkyl)amino group or tri-(C.sub.1 -C.sub.4 alkyl)ammonium halide group] or ##STR2## (wherein X is a halogen); or R.sub.1 each independently denotes --C.sub.2 H.sub.4 --Q (wherein Q is the same as defined above), ##STR3## (wherein X is the same as defined above), and R.sub.2 each independently denotes a carboxyl group or a C.sub.1 -C.sub.4 alkoxycarbonyl group, and the production thereof are described. The quarternary ammonium salt type of the above compounds exhibit affinity and photosensitizing activity for cancer cells and can be employed for diagnosing and treating cancer under irradiation of laser light.