The anti-H. pylori properties of 26 different commercial essential oils were examined in vitro by MIC (minimal inhibitory concentration) determination for the reference strain H. pylori ATCC 43504. We selected 9 essential oils with different anti-Helicobacter activities and established their phytochemical composition and urease inhibition activities. Phytochemical analysis of the selected essential oils by GC-MS method and antioxidant activity were performed. The phenol red method was used to screen the effect of essential oils on urease activity expressed as IC50 (the half of maximal inhibitory concentration). The most active essential oils, with MIC = 15.6 mg/L, were thyme, lemongrass, cedarwood and lemon balm oils; MIC = 31.3 mg/L—oregano oil; MIC = 62.5 mg/L—tea tree oil; MIC = 125 mg/L—pine needle, lemon and silver fir oils with bactericidal effect. Urease activity was inhibited by these oils with IC50 ranged from 5.3 to > 1049.9 mg/L. The most active was cedarwood oil (IC50 = 5.3 mg/L), inhibiting urease at sub-MIC concentrations (MIC = 15.6 mg/L). The statistical principal component analysis allowed for the division of the oils into three phytochemical groups differing in their anti-H. pylori activity. To summarize, the activity in vitro of the five essential oils silver fir, pine needle, tea tree, lemongrass, and cedarwood oils against H. pylori was found in this paper for the first time. The most active against clinical strains of H. pylori were cedar wood and oregano oils. Moreover, cedarwood oil inhibited the urease activity at subinhibitory concentrations. This essential oil can be regarded as a useful component of the plant preparations supporting the eradication H. pylori therapy.

Recently, several studies have been undertaken so as to develop more effective therapeutic approaches towards eradicating Helicobacter pylori. Among these is phytotherapy. The aim of this study was to investigate the activity in vitro of the plant extracts obtained from common herbs cultivated in the Lubelszczyzna region against the reference strain H. pylori ATCC 43504. Among these are thyme herbs, chamomile flowers, peppermint leaves and coneflower herbs. Herein, it was found that the MIC values of the assayed extracts were as follows: the extracts from coneflower herbs showed anti-H. pylori activity with MIC = 31.3-125 μg/ml; the extracts from chamomile flowers demonstrated MIC = 31.3-62.5 μg/ ml; the extracts from peppermint leaves had MIC = 15.6-250 μg/ml; and the extracts from thyme herbs revealed MIC = 15.6-62.5 μg/ml, depending on the solvent used. The most active were the extracts obtained with ethyl acetate or ethanol alcohol absolute 99.8%. These showing MIC within the range of 15.6-62.5 μg/ml, while the lowest activity was observed in case of the extract obtained with 70% aqueous ethanol. This last showing MIC within the range of 62.5-250 μg/ml. The MIC values of essential oil components were 15.6 μg/ml for bisabolol and menthol or 31.3 μg/ml for thymol. The obtained data indicate that the assayed herbs possessed promising anti-H. pylori bioactivity.