牛蒡提取物抑菌活性的研究

对牛蒡根茎和皮的水、50% 乙醇以及无水乙醇提取物的抑菌作用及其稳定性进行初步研究，结果表明：各种提取液对大肠杆菌、金黄色葡萄球菌、枯草芽孢杆菌、黑曲霉以及面包酵母菌均有一定的抑制作用，50% 乙醇提取液抑菌效果好于水提取液和无水乙醇提取液，且各种提取液中牛蒡皮的抑菌效果好于牛蒡根茎提取液，抑菌活性由大到小依次为金黄色葡萄球菌、枯草芽孢杆菌、大肠杆菌、黑曲霉菌、面包酵母。提取液在酸性条件下(pH3～5)抑菌效果较好，但高温(＞ 100℃)处理和紫外光长时间(≥ 5min)照射均可降低其抑菌活性。

Antimicrobial Activity of Various Solvent Extracts from Burdock (Arctium lappa) Roots and Peel

Aqueous, 50% ethanol and absolute ethanol extracts from burdock roots or peel were investigated for in vitro antimicrobial activity. Meanwhile, the thermal stability, pH stability and ultraviolet (UV) illumination stability of the extracts were also discussed. Results showed that all these extracts revealed the potential antimicrobial activities against Escherichia coil, Bacillus subtil, Staphylococcus aureus, Aspergillus niger and Saccharomyces cerevisiae. A higher antimicrobial activity was observed in 50% ethanol extracts in comparison with aqueous and absolute ethanol extracts. In addition, the extracts from burdock peel exhibited higher antimicrobial activity than those from burdock roots. Microorganisms tested were inhibited in the following order of S. aureus > B. subtilis > E. coil > Asp. niger > S. cerevisiae. The 50% ethanol extracts exhibited excellent antimicrobial activities under acidic conditions (pH 3－5), whereas both high-temperature (higher than 100 ℃) treatment and long-time (longer than or equal to 5 min) UV illumination could attenuate the antimicrobial activities.