Synthesis of the Neoglycoconjugates of Phenolic Glycolipid-related Trisaccharides for the Serodiagnosis of Leprosy

Abstract

The trisaccharide segment of the phenolic glycolipid I of Mycobacterium leprae was synthesized effectively in the form of p-(2-methoxycarbonylethyl)phenyl glycoside by the condensation of p-(2-methoxycarbonylethyl)phenyl 4-O-benzyl-3-O-methyl-α-L-rhamnopyranoside and 2, 3-di-O-methyl-4-O-(2, 4-di-O-acetyl-3, 6-di-O-methyl-β-D-glucopyranosyl)-α-L-rhamnopyranosyl chloride in the presence of silver triflate and 1, 1, 3, 3-tetra-N-methylurea, and subsequent selective deprotection. This was then coupled to BSA by the acyl azide method, giving NT-P-BSA. The NT-P-BSA showed very high reactivity and specificity to leprosy sera. The trisaccharide-BSA conjugate with a β-linked rhamnosylrhamnose unit (βT-P-BSA) was also synthesized.