Preparation and antimicrobial activity of tannin polymers from Platycarya strobilacea infructescence

Tannin polymer fractions with different molecular weight distribution are extracted and purified with macroporous resin from Platycarya strobilacea infructescence (PSI). The antimicrobial activity of the tannin polymer fractions is tested against Gram positive bacteria such as Staphylococcus aureus and Bacillus subtilis, Gram negative bacteria such as Escherichia coli and fungus Aspergillus niger. The minimum inhibitory concentration (MIC) of the tested tannin polymers in proper nutrients is determined using the broth double dilution method (serially diluted technique). For comparison, sodium benzoate is used as antimicrobial and antifungal reference drugs. All PSI tannin polymer fractions (TPF-1, TPF-2, TPF-3, TPF-4 and TPF-5) have been found to display notable antimicrobial activity against S. aureus and E. coli with low MIC values. Tannin polymer fractions with the number average molecular weight M-n of 1454 (TPF-2) and 1275 (TPF-5) have been found to exhibit broad spectrum antimicrobial activity against all the tested microorganisms. These results indicate the possibility of using P. strobilacea infructescence tannin polymers for medicinal uses.