Among a series of
fucolipids accumulating in human colonic and liver
adenocarcinoma, two neutral
fucolipids have been isolated and their
carbohydrate structures have been characterized by methylation analysis, mass spectrometry, enzymatic degradation, and
proton NMR spectrometry as shown in Structures 1 and 2 below. These
glycolipids are either absent or present in very small quantity in normal colonic mucosa and normal liver tissue. (formular; see text) Difucosyl neolactonorhexaosylceramide (Structure 1) gives a doublet or a triplet on high performance thin layer chromatography and can be separated into four to five fractions on high pressure high performance liquid chromatography. These components have the same
carbohydrate structure, but have different
fatty acid composition. Fractions are characterized by a predominance of either alpha-hydroxy C16
fatty acid or alpha-hydroxy C24
fatty acid. Trifucosyl neolactonoroctaosylceramide (structure 2) gives two discrete bands, which are designated Z3 and Z4, on high performance thin layer chromatography. Methylation analysis and nuclear magnetic resonance spectra show that the Z3 and Z4 have identical
carbohydrate structures. All the cases of
cancer tissue that accumulate di- or trifucosyl structure (1 or 2 above) also accumulated lactofucopentaose(III)
ceramide. A possible enhancement in a specific synthetic pathway including type 2 chain elongation coupled with alpha 1----3 fucosylation in human
cancer is discussed.