Antibacterial Activity and Alkaloid Content of Berberis thunbergii, Berberis vulgaris and Hydrastis canadensis

Abstract

Japanese barberry (Berberis thunbergii DC.) is a species non-native to North America but widely found as a garden ornamental. Due to its invasiveness, it has become a pest in certain parts of Maine. A comparison of alkaloid content and antibacterial activity of Japanese barberry with common barberry (Berberis vulgaris L.) has been carried out to determine whether B. thunbergii might serve as a viable substitute for more commonly used berberine-containing medicinal plants such as goldenseal (HHydrastis canadensis L.)

Extracts were prepared by exhaustively extracting B. thunbergii, B. vulgaris, and H. canadensis with 70% ethanol (ratio of roots to solvent was 1 : 5). Additional extracts were prepared with both 65% glycerin, and a mixture of 15% alcohol, 40% glycerin and 45% water (ratio of roots to solvent was 1 : 4).

The ethanolic extracts were more potent against five bacteria than either the glycerin extracts or the mixed solvent extracts. Notably, the extracts exhibited strongest activity versus bacteria associated with sore throat (Streptococcus pyogenes) and opportunistic skin infection (Staphylococcus aureus), which supports the traditional uses of berberine-containing plants. The total alkaloid content in the dried roots (% w/w) was found to be 3.47 ± 0.39 (1.38 ± 0.14 berberine) for B. thunbergii, 2.22 ± 0.12 (0.43 ± 0.02 berberine) for B. vulgaris, and 9.04 ± 0.21 (6.34 ± 0.14 berberine) for H. canadensis.

Keywords::

• Alkaloid
• antibacterial
• Berberis thunbergii
• Berberis vulgaris
• goldenseal
• Hydrastis canadensis
• HPLC-UV/MS
• Japanese barberry
• MIC
• plant extracts