Katarzyna Rybicka-Jasińska

C-C bond forming reactions catalyzed by chiral metalloporphyrins

Porphyrins are abundant in nature facilitating many enzymatic reactions by being present in the active sites of many enzymes. Consequently, over the years, a number of chiral metalloporphyrins have been synthesized and have proved efficient in catalyzing C–C bond forming reactions. Herein, we review the synthesis of chiral metalloporphyrins and their catalytic activity in cyclopropanation, cyclopropenation, and C–H insertion reactions.

Porphyrins inactivate Nosema spp. microsporidia

The study of organic/inorganic molecules with activity against intracellular fungi of the phylum Microsporidia is of critical importance. Here, for the first time, the inactivation of these parasitic fungi by porphyrins is reported. The biological effects of porphyrins (10 µM and 100 µM) on the microsporidian Nosema ceranae was investigated in honeybee hosts using cage experiments. A significant reduction in the number of spores (from 2.6 to 5 fold) was observed in Nosema-infected honeybees with a sucrose-protoporphyrin amide [PP(Asp)2] syrup diet compared to the control honeybees. PP(Asp)2 and the other porphyrin examined in vitro, TMePyP, had a direct impact on the microsporidia. Notably, neither porphyrin requires light excitation to be active against microsporidia. Moreover, microsporidia preincubated with these porphyrins exhibited decreased ability to infect honeybees. In particular, PP(Asp)2, possessing amphiphilic characteristics, exhibited significant inactivation of microsporidia, preventing the development of the microsporidia and diminishing the mortality of infected honeybees. In addition, the porphyrin-treated spores examined by scanning electron microscopy (SEM) showed morphological changes in their exosporium layers, which were distinctly deformed. Thus, we postulate that the mechanism of action of porphyrins on microsporidia is not based on photodynamic inactivation but on the destruction of the cell walls of the spores.

Synthesis of chiral porphyrins and their use in photochemical oxidation of carbonyl compounds

A series of chiral A4, A2B2, and AB3 porphyrins bearing proline moieties at the meso-phenyl group has been synthesized. Photostability studies revealed that the number of L-proline units and their position on meso-phenyl rings strongly influence the decomposition rate of the catalyst. 5,10,15-Tris(mesityl)-20-(3-prolinanilidylphenyl)-21,23H-porphyrin is the most stable while porphyrin bearing four 3-prolinanilidylphenyl substituents completely decomposes in CHCl3 within 3 h. Singlet oxygen quantum yields of the conjugates were determined by measuring the peak areas of the NIR emission of 1O2 (1280 nm) generated by these compounds and compared to that generated by the reference standard TPP. Selected porphyrins were tested as catalysts in the photooxidation of carbonyl compounds at the α-position.