RESEARCH ARTICLE
Inhibitory Effect of Herbal Compounds on the Oxygen-Insensitive NADPH Nitro Reductase Enzyme of Metronidazole-Resistant Helicobacter pylori
Sciences of Phytochemistry|Vol. 2, Issue 1, pp. 77-87 (2023)
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Received
Apr 3, 2023Revised
May 23, 2023Accepted
May 26, 2023Published
May 28, 2023
Abstract
Introduction
Helicobacter pylori is a significant risk factor for chronic gastritis, gastric ulcers, and gastric cancer (1). It is a gram-negative, spiral-shaped, flagellated bacterium that has infected almost half of the world's population (2). The annual rate of infection in developing countries ranges from 4% to 15%, while in developed countries, it is only 0.5% (3). H. pylori has developed an acid adaptation mechanism that increases the regulation of periplasmic pH in the harsh acidic environment of the stomach by regulating urease activity (4). Antimicrobial resistance (AMR) occurs when bacteria, viruses, fungi, and parasites evolve over time and no longer respond to medicines, making infections harder to treat and increasing the risk of disease spread, severe illness, and death (5). Treatment of H. pylori infection comprises a combination of antibiotics and acid-reducing proton pump inhibitors (PPIs). The most common antibiotics are metronidazole, amoxicillin, and clarithromycin. The common PPIs include pantoprazole, emiprazole, lansoprazole and rabiprazole. Combined treatments are usually prescribed for 14 days (6). In most regions of the World Health Organization (WHO), the prevalence of H. pylori AMR to metronidazole is more than 15% (7).
Acquisition of resistance is associated with the mutational inactivation of the rdxa gene, which encodes an oxygen-sensitive NADPH nitroreductase. In H. pylori, a mutation in the rdxa gene is significantly associated with metronidazole resistance (8, 9). Studies conducted in Iran have shown that the resistance of H. pylori to the metronidazole antibiotic is very high, at about 57.4%. This resistance is about 46.6% in Asian countries. The highest level of resistance of this microorganism to metronidazole is in African countries, where it reaches 97.55% (3).
Essential oils are a mixture of volatile compounds that are produced as secondary metabolites in medicinal plants. According to the International Organization for Standardization, essential oils are products extracted from plant sources or fruits using steam or water distillation methods. Their chemical compositions are very different based on factors such as the plant, environment, and extraction method. Due to their antimicrobial, antioxidant, anti-inflammatory, and anti-cancer properties, essential oils can be a suitable alternative in the food and pharmaceutical industries ().
Declarations
Acknowledgment
We appreciate and thank all the people and organizations who helped us in writing this article.
Conflict of Interest
The authors declare no conflicting interest.
Data Availability
The unpublished data is available upon request to the corresponding author.
Ethics Statement
Not applicable.
Funding Information
Not applicable.
