Synthesis, Tissue Uptake, and Toxicity of a Nickel Tetracarboranylphenylporphyrin
Porphyrins have been used for boron neutron capture therapy [BNCT] and photodynamic therapy [PDT] of experimental rodent tumors. PDT requires much less porphyrin than BNCT, typically 5 μg as compared to > 200 μg per gram body weight [gbw]. Toxicity is a major consideration in the use of boronated drugs for BNCT. At 265 μg/gbw, a boronated porphyrin, VCDP  (Figure 1) delivered 40 μg B/g to tumor tissue 4 days after the last of 12 intraperitoneal [ip] injections.1 There was transient hematologic and hepatic toxicity. If the VCDP dose rate was kept low (22 μg/gbw per ip injection; 12 injections over 4 days), lethality was under 10%. A tetraphenylporphyrin  containing four meta-nido-carborane cages was synthesized2 and when tested in mice found to be much more toxic than VCDP.
KeywordsNickel Toxicity Cage Boron CH2Cl2
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