Isolation and Characterization of Major Gangliosides from Frog Liver

Abstract

Four major gangliosides isolated from frog liver were characterized by compositional analysis involving GLC and GC-MS, methylation analysis, chromium trioxide oxidation, and enzymatic hydrolysis. The results revealed that the most major ganglioside in the tissue was GM4 containing N -acetylneuraminic acid and the others were GM4 containing N-glycolylneuraminic acid, GD1a, and a fucosyl ganglioside which was tentatively assigned to be a-galactosyl a-fucosyl GM1. This is the first report describing the presence of GM4 containing N-glycolylneuraminic acid. The fatty acids in both GM4 were mainly a-hydroxylated, and those in the fucosyl ganglioside were exclusively nonhydroxy fatty acids. The GDla contained both nonhydroxy and a-hydroxy fatty acids in a ratio of about 3:2. The predomi-nant species were 22:0, 23:0, 24:0, and 24:1 in both species of the fatty acids. The long-chain bases of these four gangliosides consisted of C₁₈-sphingosine and C₁₈-phytosphingosine together with significant amounts of C₁₆ to C₁₉ dihydroxy and trihydroxy bases with iso and anteiso structures.