Narrow Results

A method is described for preparation of monosubstituted derivatives of platinum and palladium coproporphyrin-I. The method is based on chemical differentiation of one of the four alkoxycarbonyl groups of the starting coproporphyrin-I tetraalkyl ester by selective acid hydrolysis. The hydrolysis results after chromatographic purification to pure mono hydroxycarbonyl coproporphyrin, which can be subsequently coupled with a chemical species carrying a functional group of interest. The described method is used for preparation of phosphorescent metalloporphyrin labeling reagents having an isothiocyanato reactive group.

Synthesis of monofunctional derivatives of platinum(II) and palladium(II) coproporphyrin-II with the isothiocyanato reactive group is presented. The compounds exhibit strong phosphorescence at room temperature in deoxygenated aqueous solutions and they enable facile covalent labeling of proteins and other biomolecules under slightly alkaline conditions. The performance of the compounds as phosphorescent labeling reagents is studied and the results are considered in relation to the results for the respective labeling reagent of coproporphyrin-I isomer. The results show that the derivatives of coproporphyrin-II exhibit similar reactivity and emission efficiency to that of the derivatives of coproporphyrin-I isomers. Thus, the coproporphyrin-II derivatives serve as alternative labels to coproporphyrin-I in the design of sensitive bioassays based on phosphorescence and time-resolved fluorescence detection.

An isothiocyanato-functionalized phthalocyanine (Pc) was synthesized in good yield from the corresponding amine-substituted Pc. This Pc reacted with ethanolamine, biotin hydrazine, and biotin diethylamine under mild conditions (room temperature in DMF or DMSO in the presence of TEA) to produce the corresponding thiourea products in 60–75% yields. All Pcs showed intense Q absorptions in DMF around 677 nm, emissions centered at 683 nm, and fluorescence quantum yields in the range 0.18–0.27. The Pcs were phototoxic to human carcinoma HEp2 cells (IC${}_{50}$$\sim$ 7 at 1.5 J/cm${}^2)$ and localized in multiple organelles, including the lysosomes, Golgi and ER. One biotin-Pc conjugate was injected via tail vein into nude mice bearing HT-29 tumors and demonstrated selective localization in the tumor tissue.

An isothiocyanato-functionalized phthalocyanine (Pc) was synthesized in good yield from the corresponding amine-substituted Pc. This Pc reacted with ethanolamine, biotin hydrazine, and biotin diethylamine under mild conditions (room temperature in DMF or DMSO in the presence of TEA) to produce the corresponding thiourea products in 60–75% yields. All Pcs showed intense Q absorptions in DMF around 677 nm, emissions centered at 683 nm, and fluorescence quantum yields in the range 0.18–0.27. The Pcs were phototoxic to human carcinoma HEp2 cells (IC₅₀ ~ 7 at 1.5 J/cm²) and localized in multiple organelles, including the lysosomes, Golgi and ER. One biotin-Pc conjugate was injected via tail vein into nude mice bearing HT-29 tumors and demonstrated selective localization in the tumor tissue.