Synthesis, Self-Assembling Properties and Incorporation of Carbohydrate-Substituted Porphyrins into Cell Membrane Models

Abstract

A general and very efficient synthesis of new carbohydrate-substituted porphyrins is described. Reaction of porphyrin 6 with different glycosyl imidates 7 a ± g leads to the formation of carbohydrate-substituted porphyrins 9 a ± g in good yield. Subsequent demetallation and removal of the carbohydrate protection groups leads to the metal-free compounds 11 a ± g. In aqueous solution, compounds 11 a ± g tend to form defined water-soluble aggregates in a self-assembling process. In methanol/water mixtures the aggregation process depends upon the configuration of the anomeric carbon in the carbohydrate moiety. The porphyrinic aggregates are characterized by strong exciton splitting in the Soret absorption spectrum and a red shift for all absorption bands. Interaction of the porphyrinic aggregates with phosphatidylethanolamine and DMPC liposomes leads to very efficient incorporation of mainly monomeric porphyrins 11 a ± g into the liposomes, as was indicated by very large binding constants. At low liposome concentrations noncovalent porphyrin dimers were detected.

Self‐Promoted Glycosylation for the Synthesis of β‐N‐Glycosyl Sulfonyl Amides

“…This observation is in line with Grundler and Schmidt's synthesis and attempted glycosylation with donor 6. [34] The donor has due to this only sporadically been used since the work by Schmidt and only to glycosylate reactive alcohols, [35,36] i. e. no carbohydrate alcohols, amino acid alcohols [37] or weak nucleophiles like amides. The inherent problem with glycosylation using a GlcNAc donor could be overcome by using the N-Troc protected donor 7, which gave good yields and high selectivity, when using excess of the donor (entry 19 vs 20).…”

Basic principles of photodynamic therapy

“…1 . It has been shown that aggregation changes the photophysical properties of porphyrin, chlorin, and phthalocyanine photosensitizers [85][86][87][88][89][90][91][92][93][94][95][96]. Aggregation shortens the triplet-state lifetime and decreases the singlet-oxygen quantum yield by dissipating the energy through internal conversion [92][93][94][95][96][97].…”

Multimeric glycotherapeutics: New paradigm

“…Most of the structures described in the literature are stable in non-polar organic solvents and in the solid phase. Only the classic amphiphils, such as micelles, liposomes, and aggregates of carbohydrate-substituted porphyrines [26], are able to form non-covalent structures in aqueous solutions. Our aim therefore was to design a stable inaqueous solution, non-covalent polymer instead of true polymers ( Figure 2).…”