α-Selective Solid-Phase Synthesis of Glycosyl Phosphate Repeating Structure Via the Phosphoramidite Method

Area of Science:

• Organic Chemistry
• Glycochemistry
• Parasitology

Background:

• Lipophosphoglycans (LPGs) are key surface molecules on Leishmania parasites, playing a vital role in host-parasite interactions and immune responses.
• Understanding LPG structure and function is essential for developing effective anti-Leishmania therapies.

Purpose of the Study:

• To develop a robust chemical synthesis method for producing homogeneous lipophosphoglycan (LPG) repeating units.
• To achieve the longest chemically synthesized homogeneous LPG chains to date.

Main Methods:

• Solid-phase synthesis utilizing a novel disaccharide α-1-phosphoramidite building block with para-t-butylbenzoyl protecting groups for enhanced solubility.
• Chain elongation via stable glycosyl boranophosphate linkages.
• Conversion of boranophosphodiesters to phosphodiesters using an oxaziridine derivative and a silylating reagent.

Main Results:

• Successful synthesis of disaccharide 1-phosphate repeating units of LPGs with high anomeric purity.
• Achieved α-selective synthesis of LPG chains up to 15 repeating units, the longest homogeneous chains reported.
• The developed method provides chain lengths equivalent to native LPGs.

Conclusions:

• The novel chemical synthesis provides a reliable route to long, homogeneous LPG repeating units.
• This advancement has significant implications for the development of novel anti-Leishmania pharmaceuticals and vaccines.
• The methodology offers a powerful tool for studying LPG structure-activity relationships.