Neurotoxicity of tetraphenylporphinesulfonate (TPPS4) and a hematoporphyrin derivative (Photosan) in organotypic cultures of chick embryonic dorsal root ganglia

The neurotoxic effect of tetraphenylporphinesulfonate (TPPS4) and a hematoporphyrin derivative (HPD, Photosan) has been studied in organotypic cultures of chick dorsal root ganglia maintained in a semi-solid culture medium. The changes in two characteristics of neurite outgrowth, the mean radial length of neurites growing out from the ganglia and the area of neurite outgrowths, are used as parameters to evaluate the toxic effect. The porphyrins are tested over the concentration range 10-160 micrograms ml-1. TPPS4 is slightly more toxic than the HPD Photosan. The median inhibitory concentration (IC50) for TPPS4 is 45-50 micrograms ml-1 and for the HPD Photosan 50-60 micrograms ml-1, respectively. Nevertheless, the toxicity of the two drugs is relatively low compared to that of commonly used anticancer drugs, such as cisplatin or taxol.