Purification of proanthocyanidins from nut seeds and study on its bactericidal mechanism against Streptococcus mutans.

P-AN can effectively inhibit the activity of S. mutans. P-AN can reduce the erosion of the tooth surface by the acid of S. mutans. P-AN could break the structure of the cell membrane protein of S. mutans. P-AN could destroy the integrity of membrane, resulting in the death of S. mutans.