Preliminary study of antimicrobial activities on medicinal herbs of Thai food ingredients

Abstract

To investigate the potential for use of medicinal herbs as natural antimicrobial additives for foods, the following fifteen medicinal herbs were examined for antimicrobial activity: coriander (Coriandrum sativum Linn), shallot (Allium ascalonicum L.), ginger (Zingiber offcinale Roscoe), galangal (Alpinia galanga Swartz), lemon grass (Cymbopogon citratus Stapf.), kaffir lime leaves and peels (Citrus hystrix DC), lime peels (Citrus aurantiifolia Swing), bird chili (Capsicum frutescens L.), curcuma (Curcuma longa L.), sweet basil (Ocimum basilicum L.), holy basil (Ocimum sanctum Linn), bitter cucumber (Momordica charantia L.), devil's fig (Solanum torvum Sw.) and indian malberry (Morinda citriforia L.). Fresh extracts and oil extracts of all medicinal herbs in this study were tested against Bacillus cereus, Salmonella typhi and Staphylococcus aureus by using Agar Diffusion Method. Six of them including Zingiber officinale, Allium ascalonicum, Alpinia galanga, Citrus hystrix, and Citrus aurantiforia were shown high activities in the first screening. A second screening for antimicrobial activities of six potential medicinal herbs were performed in duplication. All of six herbs exhibited antimicrobial activities against Bacillus cereus and Staphylococcus aureus, and all except Z. officinale exhibited significant activity against Salmonella typhi. Antimicrobial activities of oil extracts were higher than fresh extracts. C. hystrix, A. ascalonicum, and C. aurantiifolium were selected as potential antimicrobial food additives, and the identification of active compounds and suitable purification method in these medicinal plants have been suggested to further studies. © ISHS 2005.