In order to elucidate the relationship between the structure and anti-HIV a
ctivity of sulfonated polysaccharides, two anhydro-pentose monomers having
different configurations of substituents at C2 and C3 positions from D-ribo
se, 1,4-anhydro-2,3-di-O-tert-butyldimethylsilyl-alpha -L-arabinofuranose a
nd -D-xylofuranose, were polymerized, respectively, with PFS catalyst to gi
ve (1 --> 5)-alpha -L-arabinofuranan and (1 --> 5)-alpha -D-xylofuranan der
ivatives. After deprotection and subsequent sulfonation, sulfonated arabino
furanan and xylofuranan having Various molecular weights and degree of sulf
onation were obtained. Commercially available xylan ((1 --> 4)-beta -D-xylo
pyranan) Was also sulfonated to give sulfonated xylan. These sulfonated pen
tosans having higher degrees of sulfonation of 1.4-1.9 (maximum, 2) were fo
und to have potent anti-HIV activities in the EC50 of 0.1-0.6 mug/ml which
were as high as those of sulfonated ribofuranans and ribopyranans reported
previously, suggesting that the sulfonated pentofuranan-type polysaccharide
s having a high degree of sulfonation had potent anti-HIV activity. In addi
tion, the sulfonated arabinofuranan and xylofuranan had higher blood antico
agulant activities, 36 and 28 unit/mg, respectively, than those of sulfonat
ed xylan with six-membered pentopyranosidic unit, 14-15 unit/mg, suggesting
that the flexible furanan-type backbone structure worked effectively in th
e high activity. (C) 2001 Elsevier Science Ltd. All rights reserved.