Antibacterial activity of alkaloids from different growth parts of Berberis poiretii

  Objective  In this paper, the antibacterial activity of alkaloids from different parts (root, stem, leaf and fruit) of Berberis poiretii was evaluated to provide a theoretical basis for broadening the application fields of whole plant and developing new natural food preservatives.

  Method  Taking the diameter of bacteriostatic zone, the lowest bacteriostatic concentration and the lowest bacteriostatic concentration as the examination index, the Oxford Cup bacteriostatic method was used to study the inhibitory effects of alkaloids from different growth sites on four food-borne pathogens (Escherichia coli, Staphylococcus aureus, Salmonella spp., Bacillus subtilis), the types and contents of alkaloids were determined by high-performance liquid chromatography method.

  Result  Before and after purification, the alkaloids from 4 different parts of Berberis poiretii showed positive dose-effect relationship to four common food-borne pathogenic bacteria, i.e. Escherichia coli, Staphylococcus aureus, Salmonella spp., Bacillus subtilis. When the concentration of alkaloids was 60 g/L, the diameter of bacteriostatic zone was more than 20 mm. The minimum inhibitory concentration (MIC) to Escherichia coli, Salmonella spp. and Bacillus subtilis was 1.25 g/L, minimum bactericidal concentration (MBC) was 2.50 g/L, and the MIC to Staphylococcus aureus was 2.50 g/L, MBC was 5.00 g/L. When the concentration of alkaloid was 40 g/L, the diameter of bacteriostatic zone was more than 20 mm. The results showed that the MIC for Escherichia coli and Salmonella spp. was 0.31 g/L, MBC was 0.63 g/L, and the MIC for Bacillus subtilis and Salmonella spp. was 0.63 g/L, respectively, MBC was 1.25 g/L. The results of HPLC showed that the purified alkaloids were berberine (0.28–41.69 g), jatrorrhizine (0.32–12.67 g) and palmatine (0.25–17.09 g) .

  Conclusion  The root, stem and fruit of Berberis poiretii have stronger bacteriostatic effect on the tested strains, but the leaf has weaker bacteriostatic effect. The basic alkaloid monomers in 4 different growing parts are the same, but the content of the monomers is significantly different. When the concentration of alkaloid is 60 g/L, the order of bacteriostasis is fruit > root > stem > leaf, and the order of bacteriostasis is root > stem > fruit > leaf.