Abstract: The extraction technology by using adsorption of macroporous resin and the bacteriostatic mechanism of anthocyanin from sweetpotato were studied in an experiment. The results showed that the maximum extraction rate of anthocyanin from sweetpotato 3.81 mg·g-1 was gained on the optimal extractive conditions of 0.8% citric acid, the material to solvent ratio of 1: 200, 60oC homothermal bainmarie, 2 hours extraction time. The high purity extracts with 225.1E colour value ( E1%1cm532nm ) was obtained through purification by using AB-8 macroporous resin's adsorption, which was six times as the crude extracts. The inhibitory effects of anthocyanin from sweetpotato on growth of E.coli, S.aureus and P.aeruginos were discovered, and showed a positive correlation with the concentration of anthocyanin from sweetpotato. Observation under transmission electron microscope, SDS-PAGE analysis and comparing growth curves of normal E.coli affected by anthocyanin from sweetpotato indicated that the bacteriostatic mechanism was the combination of anthocyanin from sweetpotato with protein or enzyme in the cell and inhibiting cell division, then cell died caused the concentration and disintegration of cytoplasm. The anthocyanin from sweetpotato possesses two functions of pigment and bacteriostatis and it is a perfect natural pigment.

Key words: Sweetpotato (Ipomoca batatas. L.), Anthocyanin, Extraction, Bacteriostatic