Simple partial purification of D-pinitol from soybean leaves

There is growing interest in the use of D-pinitol (D-3-O-methyl-chiro-inositol) as a food supplement because of its reported efficacy in lowering blood glucose levels. Pinitol is a common constituent of legume plants and is a major component of soybean [Glycine max (L.) Merr.] leaves. The objective of the studies was to identify a combination of simple methods that would result in the purification of pinitol from soybean leaves. Ethanolic extracts of soybean leaves following solvent partitioning to remove lipids, passage of the aqueous fraction through ion exchange resins, and treatment of the effluent with activated charcoal yielded a white crystalline product that was 85.5% pinitol by weight. Other components in the product included D-chiro-inositol (5.2%), myo-inositol (3.4%), and ononitol (D-4-O-methyl-myo-inositol; 1.9%). Thus, 96% of the crystalline product was cyclitols following the simple purification protocol.