The extraction of pure DNA can be challenging due to the presence of sugars, oils and other endogenous chemicals present within biological samples. This is particularly true for many plants and fungi due to the presence of secondary metabolites such as polyphenols and polysaccharides. Polyphenols within the cytosol can become irreversibly DNA-bound after cell lysis and polysaccharides can co-precipitate with DNA during the extraction. Sorbitol is an osmotically active sugar alcohol and washing homogenate with sorbitol before cell lysis has been shown to significantly improve the purity of DNA extractions. Sorbitol does not pass cell membranes and likely acts by drawing the cytosol out of the cell. Therefore polyphenols and polyscacharides would be removed.