Diglucomelezitose, a novel pentasaccharide in silverleaf whitefly honeydew

Honeydew excreted by the silverleaf whitefly (Bemisia argentifolii Bellows and Pening) feeding upon upland cotton (Gossypium hirsutum L.) was isolated from cotton lint and fractionated into various oligosaccharides using a charcoal column eluted with aqueous isopropyl alcohol. ?Two oligosaccharide fractions from the charcoal column, enriched in tetra-and pentasaccharides, were further fractionated on a Bio-Gel P2 column. A fraction from the later column was separated into individual oligosaccharides using high-performance anion-exchange chromatography. One of the sugars isolated in this procedure was found to be novel pentasaccharide. Analysis of this oligosaccharide by NMR showed it to contain sucrose and melezitose moieties. The results of these analyses are consistent with a pentasaccharide of the following structure: O-alpha-D-glucopyranosyl-(1-->4 -O-alpha-D-glucopyranosyl-(1-->3)-O-beta-D-fructofuranosyl-(2<->1)-O-alpha-D-glucopyranosyl-(1-->4)-alpha-D-glucopyranoside. A tetrasaccharide, maltosucrose [O-alpha-D-glucopyranosyl-(1-->4)-O-alpha-D-glucopyranosyl-(1-->4)-O-alpha-D-glucopyranosyl-(1<->2)-beta-D-fructofuranoside], was also identified in a second fraction from the Bio-Gel column.