Ascorbyl radical scavenging activity of polyphenols.

A variety of tannin and lignin-related compounds were compared for their ability to modify the ascorbyl radical intensity of sodium ascorbate. Hot-water extracts prepared from green tea, black tea and pine cone (Pinus parviflora Sieb. et Zucc.), and various wines potently scavenged ascorbyl radical intensity. Low molecular weight tannins and phenylpropenoid monomers showed the greatest scavenging activity, whereas the dehydrogenation polymers of phenylpropenoids were much less active. On the other hand, natural lignified materials, protein-bound polysaccharide (PSK) and positively-charged glucans enhanced the ascorbyl radical intensity. Lignin sulfonate stimulated the sodium ascorbate-induced cytotoxicity in human promyelocytic leukemic HL-60 cells. These data suggest that the ascorbyl radical scavenging activity of polyphenols depends on molecular weight, the functional group and the presence of polysaccharides in the molecule.