Longifoside-A and -B: two new cerebrosides from Mentha longifolia (Lamiaceae)

Two new N-acyl-glycosphingosines (cerebrosides) named longifoside-A {6'-tetracosenamide, N-3,4-dihydroxy-1-(hydroxymethyl)-2-(beta-D-glucopyranosyl) heptadecyl]-(6'E)} and B {6'-tetracosenamide, N-3-hydroxy-1-(hydroxymethyl)-2-(beta-D-glucopyranosyl)-4Z-heptadecenyl]-(6'E)} have been obtained from the methanolic extract of Mentha longifolia belonging to the family Lamiaceae. Both the cerebrosides were purified as their acetate-derivatives: 6'-tetracosenamide, N-3,4-diacetoxy-1-(acetoxymethyl)-2-(tetraacetoxy-beta-D-glucopyranosyl) heptadecyl]-(6'E) and 6'-tetracosenamide, N-3-acetoxy-1-(acetoxymethyl)-2-(tetraacetoxy-beta-D-glucopyranosyl)-4Z-heptadecenyl]-(6'E). They were characterized with the aid of 1D and sophisticated 2D-NMR spectroscopic techniques.