A novel oligosaccharide, xylosyl beta 1-4xylosyl beta 1-(4-methylumbelliferone), synthesized by cultured human skin fibroblasts in the presence of 4-methylumbelliferyl-beta-D-xyloside.

4-Methylumbelliferyl-beta-D-xyloside (Xyl-MU) was added to the medium of cultured human skin fibroblasts. After incubation, the culture medium was pooled, concentrated with a lyophilizer, and dialyzed against distilled water. Then the Xyl-MU derivatives in the diffusate were purified by gel-filtration and HPLC. A novel Xyl-MU derivative was obtained, in addition to the previously reported Xyl-MU derivatives, Xyl-MU-induced glycosaminoglycan (GAG-MU), SA-Gal-Xyl-MU, GlcA-Xyl-MU, Gal-Gal-Xyl-MU, and Gal-Xyl-MU. This Xyl-MU derivative was subjected to carbohydrate composition analysis, enzyme digestion, Smith degradation and ion-spray mass spectrometric analysis, and the results indicated that it was Xyl beta 1-4Xyl beta 1-MU. Although the quantity of Xyl beta 1-4Xyl beta 1-MU synthesized by human skin fibroblasts increased with incubation time, its production was independent of that of the GAG-MU. Xyl-Xyl-MU is different from the intermediates in the regular pathway of GAG-MU biosynthesis initiated by added Xyl-MU, posing an interesting question as to its significance in GAG biosynthesis.