4-O-β-D-Galactopyranosyl-D-xylose: A new synthesis and application to the evaluation of intestinal lactase

Article abstract of DOI:10.1016/S0008-6215(00)90554-8

4-O-β-D-Galactopyranosyl-D-xylose (2) was prepared from benzyl 2,3-O-isopropylidene-β-D-xylopyranoside by glycosylation with 2,3,4,6-tetra-O-benzoyl-α-D-galactopyranosyl bromide and subsequent deprotection. Compound 2 was hydrolyzed in vitro by intestinal lactase; the V(max) was 25% of that with lactose and the K(m) was 370 mM (cf. 27 mM for lactose). Oral administration of 2 to suckling rats led to urinary excretion of D-xylose which could be estimated colorimetrically. 4-O-β-D-Galactopyranosyl-D-xylose (2) was prepared from benzyl 2,3-O-isopropylidene-β-D-xylopyranoside by glycosylation with 2,3,4,6-tetra-O-benzoyl-α-D-galactopyranosyl bromide and subsequent deprotection. Compound 2 was hydrolyzed in vitro by intestinal lactase; the V_max was 25% of that with lactose and the K_tu was 370mM (cf. 27mM for lactose). Oral administration of 2 to suckling rats led to urinary excretion of D-xylose which could be estimated colorimetrically.