E. Pando

An acidic xyloglucan from grape skins

Abstract The structure of one hemicellulose A fraction (A-1) isolated from grape skins ( Vitis vinifera ) of the Palomino variety has been studied by methylation analysis, NMR spectroscopy and partial acid hydrolysis. Hemicellulose A-1 appeared to be homogeneous with a weight-average M r of 35 544. It was shown to be a linear acidic xyloglucan constituted by a linear chain of xylopyranosyl and glucopyranosyl residues linked by β-(1 → 4) glycosidic bonds containing 4- O -methylglucuronopyranosy acid, l -arabinofuranosyl and xylopyranosyl residues attached at position 2, in a ratio of one residue for every 10 units of xylose in the main chain, and l -arabinofuranosyl and glucopyranosyl residues attached at position 6 of the units of glucose, in a ratio of one residue for every four glucoses in the main chain.

Meridinol, a lignan from Zanthoxylum fagara

Abstract The structure of a novel lignan, meridinol, isolated from Zanthoxylum fagara was determined by the evidence of its spectroscopic data and X-ray single crystal structure as (1 S, 2R)-1,2-bis (3,4-methylenedioxy benzyl)- 1-hydroxy butyrolactone.

Structure of a hemicellulose A fraction in dietary fiber from the seed of grape variety Palomino (Vitis vinifera cv. palomino).

The structure of one of the hemicellulose A fractions (HA-1) extracted from the seeds of the grape variety Palomino (Vitis vinifera cv. Palomino) has been studied by means of methylation, 1H NMR, 13C NMR, and partial hydrolysis. This hemicellulose seems to be a homogeneous polysaccharide with an apparent molecular weight of 68 500. Its structure is that of an acidic xylan, a linear chain of beta-D-xylopyranosyl units, bonded together by (1-->4) glycosidic links, containing single alpha-D-xylopyranosyl and 4-O-methyl-alpha-D-glucopyranuronosyl residues joined by glycosidic links to position 2 of the xylose units of the main chain, in proportions of one residue to every 25 units of xylose.