Comparison of the antibacterial activity of essential oils and extracts of medicinal and culinary herbs to investigate potential new treatments for irritable bowel syndrome. Biochemistry Group, College of Medicine, Care of Grove Reception, Swansea University, Singleton Park, Swansea SA2 8. PP, UK2. Welsh Centre for Printing and Coating, College of Engineering, The Talbot Building, Swansea University, Singleton Park, Swansea SA2 8. PP, UK3. College of Science, The Wallace Building, Swansea University, Singleton Park, Swansea SA2 8. PP, UKCorresponding author.#Contributed equally. Received 2. 01. 2 Oct 1.
Accepted 2. 01. 3 Nov 2. Copyright © 2. 01. Thompson et al.; licensee Bio. Med Central Ltd. This is an open access article distributed under the terms of the Creative Commons Attribution License (http: //creativecommons. This article has been cited by other articles in PMC. Abstract. Background. Irritable bowel syndrome (IBS) is a common functional gastrointestinal disorder, which may result from alteration of the gastrointestinal microbiota following gastrointestinal infection, or with intestinal dysbiosis or small intestinal bacterial overgrowth. This comprehensive review outlines the impact of military-relevant respiratory infections, with special attention to recruit training environments, influenza. This may be treated with antibiotics, but there is concern that widespread antibiotic use might lead to antibiotic resistance. Some herbal medicines have been shown to be beneficial, but their mechanism(s) of action remain incompletely understood. To try to understand whether antibacterial properties might be involved in the efficacy of these herbal medicines, and to investigate potential new treatments for IBS, we have conducted a preliminary study in vitro to compare the antibacterial activity of the essential oils of culinary and medicinal herbs against the bacterium, Esherichia coli. Methods. Essential oils were tested for their ability to inhibit E. E. coli in a zone of clearance assay. Extracts of coriander, lemon balm and spearmint leaves were tested for their antibacterial activity in the disc diffusion assay. Disc diffusion and zone of clearance assays were analysed by two- tailed t tests whereas ANOVA was performed for the turbidometric assays. Results. Most of the oils exhibited antibacterial activity in all three assays, however peppermint, lemon balm and coriander seed oils were most potent, with peppermint and coriander seed oils being more potent than the antibiotic rifaximin in the disc diffusion assay. The compounds present in these oils were identified by gas chromatography mass spectrometry. Finally, extracts were made of spearmint, lemon balm and coriander leaves with various solvents and these were tested for their antibacterial activity against E. In each case, extracts made with ethanol and methanol exhibited potent antibacterial activity. Conclusions. Many of the essential oils had antibacterial activity in the three assays, suggesting that they would be good candidates for testing in clinical trials. The observed antibacterial activity of ethanolic extracts of coriander, lemon balm and spearmint leaves suggests a mechanistic explanation for the efficacy of a mixture of coriander, lemon balm and mint extracts against IBS in a published clinical trial. Keywords: Irritable bowel syndrome, IBS, Small intestinal bacterial overgrowth, SIBO, Herbal medicine, Antibacterial, Antimicrobial, Essential oil. Background. Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder, which affects 1. UK population and is responsible for 2. IBS is characterised by altered bowel habit, pain, and wind or bloating, which all severely affect quality of life and may last for decades. IBS can be classified into subgroups depending on the predominant bowel symptom, namely constipation- predominant (IBS- C), diarrhoea- predominant (IBS- D) or alternating between the two (IBS- A) [2,3]. Post- infectious (PI) IBS may arise after an episode of acute gastroenteritis [4]. The causes of IBS remain poorly understood, and include altered gut motor function, visceral hypersensitivity, abnormal gas handling, alterations in the central nervous system, mild inflammation, disturbances in serotonin handling and genetic factors (reviewed in [5]). Evidence has been mounting in the past decade that alterations in the gastrointestinal microbiota may also play a role in IBS. An early study showed that patients with IBS- D excreted abnormally high levels of hydrogen compared to healthy individuals, suggesting that there was abnormal bacterial fermentation of ingested foods [6]. An exclusion diet reduced this. More recently the gastrointestinal microbiota of IBS patients have been compared with those from healthy subjects by bacterial culture or molecular approaches [reviewed in [7,8]. Many studies have found alterations in the numbers of bacterial species present, or in the abundance of particular bacterial species. The findings vary, but a common feature seems to be a reduction in the number of Bifidobacteria and increased numbers of Firmicutes and Enterobacteriaceae in samples from IBS patients compared to control samples. IBS has also been linked to small intestinal bacterial overgrowth, [reviewed in [7,9,1. In SIBO, bacterial numbers can rise from normal levels of 1. SIBO is currently defined as the presence of ≥ 1 × 1. In contrast to the normal situation in which digestion and absorption of food is complete before the bolus reaches bacteria in the colon, in patients with SIBO, ingested food comes into contact with bacteria in the jejunum and ileum, and is fermented to produce gas, which has been visualised in the small intestine by abdominal radiography [1. SIBO is typically diagnosed by giving patients a drink containing a poorly digestible sugar such as lactulose, and analysing their breath gases at intervals (reviewed in [1. Glucose can also be used. The main gases excreted are hydrogen, which is associated with IBS- D, and methane, which is associated with IBS- C [1. In one study, 7. 8% of IBS patients tested positive for SIBO using the lactulose hydrogen breath test (LHBT) [2. There is currently some controversy surrounding the use of lactulose hydrogen breath tests to diagnose SIBO and, consequently, the role of SIBO in IBS. Early breath tests diagnosed SIBO if hydrogen was excreted in two bursts, corresponding to bacterial fermentation in the small intestine, and in the colon. Later, hydrogen excretion within 9. SIBO. However, a recent study has combined LHBTs with scintigraphy to follow the movement of a radiolabelled tracer through the gastrointestinal tract [2. Hydrogen excretion within 9. SIBO [2. 3], and it has been suggested that glucose would be a better fermentation substrate since it is absorbed before it reaches the colon [1. Using the ability to culture 1 × 1. SIBO diagnosis, SIBO was diagnosed in 4% of IBS patients and healthy control subjects in one study [1. IBS patients in another [2. Modestly raised bacterial counts (≥ 1 × 1. IBS patients compared to 1. IBS patients in the second [2. IBS. Of note, lipopolysaccharide from Gram- negative bacteria speeds up gastrointestinal transit [2. LHBT (and IBS) without fermenting the lactulose themselves. One Gram- negative bacterium that has been implicated in IBS and SIBO is Escherichia coli. An early study found E. SIBO [2. 7]. E. coli was present in jejunal and duodenal aspirates from patients with IBS and SIBO [1. Klebsiella and Enterococcus species. E. coli was found to be more prevalent in the mucosal microbiota of IBS patients than those of healthy control subjects when biopsy specimens were labelled with fluorescent in situ hybridisation probes [2. E. coli were present in higher numbers in faecal samples from IBS patients than those from healthy individuals [2. There are currently various medicines available to treat IBS, including fiber, antispasmodic agents, and antidepressants to modulate pain perception [3. Tricyclic antidepressants block diarrhoea whereas serotonin reuptake inhibitors can benefit IBS- C patients by stimulating gastrointestinal motility [3. In agreement with the idea that alterations in the gastrointestinal microbiota are involved in IBS, there has been considerable success with treatments that reverse this. Clinical trials have shown that antibiotics can be effective in treating IBS [3. Successful eradication of SIBO, and reversal of the symptoms of IBS have been achieved by treating IBS patients with antibiotics such as metronidazole [3. IBS- C patients who produce methane [3. Google. Say "Ok Google" to start a voice search. Search without lifting a finger. When you say "Ok Google", Chrome will search for what you say next.
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