Porphyrins with directly meso-attached disaccharide moieties: Synthesis, self-assembly and cellular study

Abstract

A series of porphyrins with directly meso-attached “sucrose” moiety by the carbon C-6′ of its “fructose” end was synthesized, and their physico-chemical and aggregation properties studied by spectroscopic (fluorescence, circular dichroism, resonance light scattering) techniques. The effect of selected porphyrins on tumor cells was also evaluated.

The Self-Aggregation of Porphyrins with Multiple Chiral Centers in Organic/Aqueous Media: The Case of Sugar- and Steroid-Porphyrin Conjugates

“…Following the first road, we have prepared a series of porphyrin–carbohydrate conjugates with “sugar” moieties directly placed in the meso-position via robust covalent C-C links [ 34 , 35 , 38 ], showing more stability towards hydrolytic or enzymatic degradation relative to the O -glycosidic bonds generally used ( Scheme 1 ). The choice of the appended, polar sugars in combination with the lipophilic pentafluorophenyl substituents (C 6 F 5 ) was dictated by the will to finely tune the amphiphilic properties of the porphyrin platforms and, thus, their aggregative behavior in aqueous media.…”

“…With this finding in mind, we recently studied how the particular molecular structure of the selected “sugar” moiety can influence the self-aggregation behavior of porphyrin–sugar conjugates in aqueous media. For such a purpose, porphyrin 5 with a more complex sugar group appended on the 10- and 20- meso positions (i.e., sucrose) was synthesized and preliminary results on its self-assembly attitude were directly compared with the A 2 B 2 porphyrin analogues 2 and 4 [ 38 ]. As a main outcome, we found that 5 formed aggregated species in dimethyl acetamide (DMAC) or dimethylformamide (DMF)–water mixtures (3:2, v / v ), featuring unexpected CD spectra.…”

“… Glycoporphyin conjugates ( 1 – 5 ) employed in the aggregation studies thoroughly reported in References [ 34 , 35 , 38 ]. …”

“…For many years, we have focused on the possibility to build up chiral porphyrin suprastructures by assembling inherently chiral porphyrin derivatives having single or multiple stereogenic centers peripherally located on the macrocycle thanks to the conjugation with diverse biomolecules, as amino acids, glucosides or steroids [ 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 ]. The self-aggregation of these compounds was induced in organic/aqueous mixtures by the so-called “good-bad” solvent protocol, in which porphyrins solubilization in a “good” solvent is followed by the addition of the proper amount of a “bad” one, where typically the macrocycle is insoluble, even at low concentrations.…”