Antimicrobial Activities in vitro of Extracts from Seven Chinese Edible and Medicinal Herbs Commonly Used in Hakka Area

Houttuynia cordata, Cassia mimosoides, Gynostemma pentaphyllum, Rabdosin sarra, Paederia scandens, Patrinia villosa and Sophora flavescens used for relieving heat and detoxification were investigated for the screening of potential food preservatives of natural origin. Antimicrobial activity in vitro of crude aqueous and 95% ethanol extracts of the whole plants by traditional decocting method (TDM) or ultrasonic-assisted method (UAM) were examined against four species of microorganisms: Escherichia coli, Bacillus subtilis, Staphylococcus aureus and Saccharomyces cerevisiae using filter paper method, Oxford plate method and turbidity test, respectively. The extracts were found to have different levels of antimicrobial activity in the systems tested. The extract of Sophora flavescens showed the highest value of activity. The results indicated aqueous extract from Cassia mimosoides and 95% ethanol extract from Sophora flavescens by UAM had high activity (with a MIC value of 25mg/ml and 44mg/ml, respectively) and satisfactory extraction rate (9.9% and 17.5%, respectively), warranting further investigation.