comparison of the spectra obtained with those of a number of porphyrins used as standards ( protoporphyrin , uroporphyrin , and coproporphyrins ) shows that the autofluorescence excited at about 400 nm ( soret band ) is due to the presence of a mixture of these or other porphyrins in the nerve .
C0042093
uroporphyrin
C0032712
porphyrins