Journal of Applied Bacteriology zyxwvutsrqpon 1996, 80, 667-672 In vitro zyxwv inhibition of Helicobacterpylori by extracts of thyme M. Tabak, R. Armon', 1. PotasmanZ and 1. Neeman Food Engineering & Biotechnology Faculty, and 'Environmental & Water Resources Engineering, Technion, and Bnei-Zion Medical Center, Haifa, Israel 5555/11/95: received 15 November 1995, revised and accepted 13 December 1995 M. TABAK. R. ARMON, zyxwvutsrqpo I. POTASMAN AND I. NEEMAN. 1996. Extracts Of Several plants were tested for inhibitory activity against zyxwvuts Helicobacter zyxwvu pylori. Among these plants thyme (aqueous extract) and cinnamon (alcoholic extract) were the most effective. Since aqueous extract of thyme is easier to produce and consume, it was further investigated. Compared with several antibacterials, the thyme extract had a significant inhibitory effect on H. pylori, reducing both its growth and potent urease activity. From the results of this study, the aqueous extract of thyme possesses a therapeutic potential which merits validation by clinical studies. INTRODUCTION and the possible side-effect, a study of medicinal plant extracts was undertaken. In the present study, the capability of several medicinal plant extracts to inhibit growth of H . pylori was investigated. Helicobacter pylori is an important aetiological agent of chronic gastritis, peptic ulceration and gastric cancer in humans (Buck 1990; Karttunen et al. 1991; Blaser 1992; Parsonnet 1993). T h e S-shaped Gram-negative bacterium colonizes the gastric epithelial surface, and withstands the stomach's hostile ambience by microaerophilic growth capa- bility and high urease activity (Hazel1 and Lee 1986; Good- MATERIALS AND METHODS Plant extract procedure win and Armstrong 1990). Colloidal bismuth subcitrate (CBS) together with antibiotics, such as amoxycillin, metro- nidazole, is current therapy against Helicobacter p.ylori (And- reasen and Andersen 1987 ; Marshall 1993). Helicobacter pylori was also isolated from patients' dental plaques, and these were suggested as a possible source of infection relapse (Desai et a/. 1991), which could explain why CBS chewable The following plants were tested : Majorana syrica, Inulu viscosa, Rosmarinus ojicinalis, Glycirrhiza glabra, Matricaria aurea, Cinnamonum zeylanicum, Laurus nobilis, Melissa ojJcinulis, Thymus vulgaris, Saluiu ofji'cinalis and Allium zy sati- aum. The extraction procedures by alcohol and water are described in Fig. 1. tablets have been found more effective in eradication of H. pylori than ingestible tablets of the same composition (Rauws Bacterial isolates and Tytgat 1990). For long-term eradication, the triple therapy is considered highly efficient, with 80°/0 of patients showing absence of pathogen (Graham et zyxwvutsrqpo al. 1992; Moss and Calam 1992), albeit there are side-effects such as diarrhoea and colitis sometimes associated with Clostridium dzfJile (Bayerdorffer and Ottenjam 1988). Several authors have previously reported that plant extracts exhibit an inhibitory activity on bacteria in vitro and in vivo, and thus possess therapeutic potential (Zaika 1988; Toda et al. 1989, 1991 ; Diker et ul. 1991 ; Kaiidil eta/. 1994). Since an incomplete cure was achieved with the triple therapy Clinical isolates of Helicobacter p.ylori were obtained from the Ezra Health Laboratory (Haifa, Israel). Primary isolation was performed on selective Blood Agar base No. 2 (Oxoid Ltd, Basingstoke, Hants, UK) supplemented with horse blood 5% (v/v) and 1 selectatab tablet 500 ml-' (Mast Diagnostic, Merseyside, UK), which contained : Vancomycin 5 mg, Poly- myxin B 25 000 U, Trimethropim lactate 2.5 mg, Fungizone 1.0 mg, Novobiocin 2.5 mg and Bacitracin 12.5 mg, final pH 7.4. Following primary selective isolation, H. pylori bacterial cells were identified according to colony morphology, Gram staining, microaerophilic growth (at 37"C), oxidase+, cata- lase', urease+, nitrate-, H2S-, hippurate hydrolysis- and nalidixic acidrUr (Goodwin and Armstrong 1990). Growth of H. pylori was maintained under microaerophilic Correspondence to: Dr Ishak Neeman, Food Engineering 6 Biotechnolugy Faculty, Terhnion, Huifb 32000, Israel. 0 1996 The Society for Applied Bacteriology