Effects of plant essential oils and their constituents on Helicobacter pylori: A review

Essential oils (EOs) obtained from different medicinal and aromatic plant families by steam distillation have been used in the pharmaceutical, food, and fragrance industries. The plant EOs and their broad diversity of chemi-cal components have attracted researchers worldwide due to their human health benefits and antibacterial properties, especially their treatment of Helicobacter pylori infection. Since H. pylori has been known to be respon-sible for various gastric and duodenal diseases such as atrophic gastritis, peptic ulcer, gastric adenocarcinoma, and mucosa-associated lymphoid tissue lymphoma, several combination antibiotic therapies have been in-creasingly used to enhance the eradication rate of the bacterial infection. However, in the last decades, the efficacy of the therapies has decreased significantly due to widespread emergence of multidrug resistant strains of H. pylori. In addition, side-effects from commonly used antibiotics and re-currence of the bacterial infection have drawn public health concern global-ly. Therefore, this review focuses on in vitro effects of plant EOs and their bioactive constituents on the growth, cell morphology and integrity, biofilm formation, motility, adhesion, and urease activity of H. pylori. Their inhibitory effects on expression of genes necessary for growth and virulence factor productions of the bacterial pathogen are also discussed. Further in vivo and clinical evaluations are required so that plant EOs and their bio-active constituents can be possibly applicable in pharmacy or as adjuvants to the current therapies of H. pylori infection.