Total Synthesis of a Partial Structure from Arabinogalactan and Its Application for Allergy Prevention

Abstract

Arabinogalactan, a microheterogeneous polysaccharide occurring in plants, is known for its allergy‐protective activity, which could potentially be used for preventive allergy treatment. New treatment options are highly desirable, especially in a preventive manner, due to the constant rise of atopic diseases worldwide. The structural origin of the allergy‐protective activity of arabinogalactan is, however, still unclear and isolation of the polysaccharide is not feasible for pharmaceutical applications due to a variation of the activity of the natural product and contaminations with endotoxins. Therefore, a pentasaccharide partial structure was selected for total synthesis and subsequently coupled to a carrier protein to form a neoglycoconjugate. The allergy‐protective activity of arabinogalactan could be reproduced with the partial structure in subsequent in vivo experiments. This is the first example of a successful simplification of arabinogalactan with a single partial structure while retaining its allergy‐preventive potential.

Expanding the Scope of Group Transfer Radical Reaction: Toward the Synthesis of Fluorinated Nucleoside Analogues Incorporating Difluorophosphonylated Allylic Ether Moieties

“…Acetate 20 (α/β 5/95) was easily prepared in 73% yield by treatment of (β)-acetal 18 with acetic anhydride in the presence of a catalytic amount of sulfuric acid following a standard procedure . Trichloroacetamidate 21 was synthesized from hemiketal 19 (α/β 50/50), obtained by hydrolysis of (β)- 18 in acetone/H 2 O at 50 °C for 6 h .…”