Narrow Results

The review summarizes the synthesis and study of properties of the bioconjugates of chlorophyll a and bacteriochlorophyll a with carbohydrates, carboranes and other moieties, focusing on the synthetic methods of obtaining conjugates and preliminary biological testing thereof. Boronated chlorins and bacteriochlorins can be used in both photodynamic and boron neutron capture therapy.

Glucose-, galactose- and lactose-containing photosensitizers based on derivatives of chlorophyll a and bacteriochlorophyll a were synthesized with the use of [3+2] cycloaddition between sugar azides and triple bond derivatives of chlorins and bacteriochlorins. Unlike bacteriochlorin cycloimide, chlorin was detected to form a Cu-complex during the click reaction. An approach to the synthesis of metal-free glycosylated chlorins was developed with the use of "protection" by Zn²⁺ cation and subsequent demetalation. It is based on the action of alkynyl chlorin e₆ derivative Zn-complex, which is resistant to the substitution by copper cation. Bacteriochlorin p cycloimide conjugate with per-acetylated β-D-lactose was obtained and shown to become water-soluble after unblocking of the lactose hydroxy functions. NMR studies allowed for the elucidation of structure, tautomeric form and conformation of the obtained compounds.

A regioselective synthesis of glycoconjugates based on bacteriochlorophyll a and lactose derivatives has been carried out. The conjugation was achieved via 1,3-dipolar cycloaddition of bacteriochlorins containing a terminal triple bond and a lactose azide derivative. The conjugates obtained in this way had one or two disaccharide fragments attached to pyrrol A, the exocyclic imide ring of the tetrapyrrolyc macrocycle, or to both positions. Exhaustive NMR analysis by 1D and 2D NMR experiments (¹H-¹H COSY, TOCSY, ROESY, ¹H-¹³C HSQC, HMBC, and ¹H-¹⁵N HMBC) allowed us to determine the structures and configurations of the glycoconjugates obtained. A bioassay of the glycoconjugates using the Hep2 cell line showed that the highest efficiency was observed for the glycosylated bacteriopurpurinimide containing a lactose residue at pyrrole ring A.

Macromolecular assemblies, like viruses, are often built by multiple copies of a few components. These may have similar or diverse functions. The multivalency of the assembly allows ligand recognition with high avidity. Nevertheless, affinity is linked to the monovalent ligand interaction, related to the nature of the interactive surface. Such interactions can be followed in real time by the aid of surface plasmon resonance. Thus a sensor surface may be prepared with either the assembly or the ligand immobilized at the sensor and their interaction studied. Kinetic and thermodynamic properties of ligand binding to the macro-molecular assembly can be determined. Variations in the structure of the assembly, like those occurring during virus infection may also be revealed by this technique.