Constituents of holothuroidea, 18.¹ isolation and structure of biologically active disialo- and trisialo-gangliosides from the sea cucumber Cucumaria echinata

Three new disialo- and trisialo-gangliosides, CEG-6 (6), CEG-8 (8), and CEG-9 (9), were obtained, together with one known ganglioside, HLG-3 (7), from the lipid fraction of the chloroform/methanol extract of the sea cucumber Cucumaria echinata. The structures of the new gangliosides were determined on the basis of chemical and spectroscopic evidence to be 1-O-[α-L- fucopyranosyl-(1→11)-(N-glycolyl-α-D-neuraminosyl)-(2→4) -(N-acetyl-α-D-neuraminosyl)-(2→6)-β-D-glucopyranosyl]-ceramide (6) and 1-O-[(N-glycolyl-D-neuraminosyl)-(2→11)-(N-glycolyl-D-neuraminosyl) -(2→4)-(N-acetyl-D-neuraminosyl)-(2→6)-D-glucopyranosyl]-ceramide (8, 9). The ceramide moieties of each compound were composed of an homogeneous sphingosine or phytosphingosine base and heterogeneous 2-hydroxy or nonhydroxylated fatty acid units. These gangliosides showed neuritogenic activity toward the rat pheochromocytoma cell line PC-12 in the presence of nerve growth factor.