The influence of starch derivatives with benzene or halogenated benzene on antibacterial activity

In order to improve the bioactivity of starch, a group of starch derivatives containing benzene or halogenated benzene were synthesized by the reaction of chloracetyl starch ( CAST) with the Schiff bases bearing 3-amino-pyridine, including (2-pyridyl) acetyl starch chloride ( PAST), 2-(4(4-benzylideneamino)-pyridyl) acetyl starch chloride (BPAST), 2-(4-(4-brominbenzylideneamino)-pyridyl) acetyl starch chloride (4BBPAST), and 2-(4-(4-chlorobenzylideneamino)-pyridyl) acetyl starch chloride (4CBPAST). Their structure characteristics were established based on FT-IR, H-1 NMR, and C-13 NMR spectra. Their antibacterial activities against Escherichia coli and Staphylococcus aureus were estimated by the optical density method. The best inhibitory derivative was 4CBPAST, which resisted E. coli and S. aureus with the inhibitory indices of 100 and 99% at 1.0 mg/mL. Generally, because of the different electron-withdrawing properties of the substitute groups, the starch derivatives presented different antibacterial activities and their inhibitory activity decreased roughly in the order: 4CBPAST> 4BBPAST> BPAST> PAST> CAST> starch. This experiment provides a method to improve the antibacterial activity of starch and lays a foundation for the development of high-value starch.