Masanobu Haga

Structure and antitumor activity of a branched (1→3)-β-d-glucan from the alkaline extract of Amanita muscaria☆

A beta-(1----6)-branched (1----3)-beta-D-glucan(AM-ASN) was isolated from the alkaline extract of the fruiting bodies of Amanita muscaria. AM-ASN had [alpha]D - 11 degrees in 0.5 M sodium hydroxide. Its estimated molecular weight was 95,000 in this alkaline solution and 260,000 in a neutral solution. The branches in the glucan were primarily single, (1----6)-linked D-glucopyranosyl groups, two for every seven residues in the (1----3)-linked main chain. AM-ASN exhibited significant antitumor activity against Sarcoma 180 in mice, and a mixture of AM-ASN with mitomycin C was more effective against the tumor than mitomycin C only.

Diisopropylidene acetals of D-allose and D-ribo-hexulose (D-psicose)☆

Abstract Acetonation of D -allose in the presence of sulfuric acid gives 2,3:5,6-di- O -isopropylidene-β- D -allofuranose ( 4 ) in good yield. Oxidation of 4 with methyl sulfoxide and acetic anhydride gave 2,3:5,6-di- O -isopropylidene- D -allono-1,4-lactone (7). Compound 4 was also obtained from 1,2:5,6-di- O isopropylidene-α- D -allofuranose ( 1 ) in one step by an acetal-migration reaction. The acetonation of D - ribo -hexulose ( D -psicose) in the presence of anhydrous copper sulfate and sulfuric acid has been re-examined, and the main product has been shown to be 1,2:3,4-di- O -isopropylidene- D -psicofuranose ( 12 ), by conversion of 12 into 6-deoxy- D -psicose ( 16 ) through 1,2:3,4-di- O isopropylidene-6- O-p -tolylsulfonyl- D -psicofuranose ( 14 ).

Synthesis and reactions of glycosyl methyl- and benzyl-xanthates: A facile synthesis of 1-thioglycosides

Abstract Treatment of acetylated glycosyl bromides of d -galactose, d -glucuronic acid, and d -xylose with potassium methyl- and benzyl-xanthates in alcohol affords the corresponding glycosyl methyl- and benzyl-xanthates respectively. The same condensation in acetone yields the corresponding 1-thioglycosides and diglycosyl sulfides instead of glycosyl xanthates. The glycosyl xanthates, on heating with sodium iodide in acetone, give the corresponding 1-thioglycosides in high yield. The mechanism of decomposition of glycosyl xanthates is discussed in detail.