New types of glycolipids from the surface lipids of Nicotiana umbratica

The surface lipids of Nicotiana umbratica contained several varieties of glycolipids. Three types of glucose esters and five types of sucrose esters were isolated and identified from this species. These glycolipids contained short-chain fatty acids such as acetic, methylpropionic, methylbutyric, 3-methylpentanoic, 4-methylpentanoic and methylhexanoic acids. The acetylated positions of each compound were determined by 2-D NMR, using the HMBC technique. The structures of the glucose esters were 1,6-di-O-acetyl-2,3-4-tri-O-acyl-alpha-D-glucopyranose (I), 6-O-acetyl-2,3,4-tri-O-acyl-alpha-D-glucopyranose (II) and 2,3,4-tri-O-acyl-alpha, beta-D-glucopyranose (III). The structures of the sucrose esters were 6-O-acetyl-2,3,4-tri-O-acyl-alpha-D-glucopyranosyl-1,3-di-O-acetyl-beta- D- fructofuranoside (IV), 2,3,4-tri-O-acyl-alpha-D-glucopyranosyl-1,3-di-O-acetyl-beta-D-fructofur anoside (V), 6-O-acetyl-2,4-di-O-acyl-alpha-D-glucopyranosyl-3-O-acetyl-beta-D- fructofuranoside (VI), 2,3,4-tri-O-acyl-alpha-D-glucopyranosyl-3-O-acetyl-beta-D-fructofuranosi de 2,3,4-tri-O-acyl-alpha-D-glucopyranosyl-3-O-acetyl-beta-D-fructofuranosi de (VII) and 2,3,4-tri-O-acyl-alpha-D-glucopyranosyl-beta-D-fructofuranoside (VIII). Among them, I, IV, V and VI were isolated for the first time from plants of the family Solanaceae. These newly isolated glycolipids were inhibitory against barnyardgrass growth.