Anti-Helicobacter Pylori Activity From Natural Products: Difference between revisions

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====Acetone and Methanol Extracts====
====Acetone and Methanol Extracts====
Many plants from the Middle Eastern, Mediterranean, and Indian area have traditionally been used to treat common ailments.  Acetone and methanol extracts from these plants possess some antibacterial properties against different strains of H. pylori.  Using the agar dilution method, the minimum inhibitory concentrations of acetone, methanol, and water extracts were determined from various plants in the Punjab province of Pakistan.  The extracts’ ability to inhibit H. pylori urease was assessed by the phenol red method.  The methanol and acetone extracts from Acacia nilotica and Calotropis procera had significant antibacterial activity and urease inhibition but were less powerful compared to amoxicillin and clarithromycin.  The extracts from Acacia nilotica and Calotropis procera exhibited different mechanisms of inhibition: competitive and mixed, respectively.
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Combretum molle from South Africa has been widely used to treat gastric ulcers.  The agar diffusion method showed the MIC of five different solvent extracts: acetone, ethanol, water, crude extract, and ethyl acetate.  All the solvent extracts demonstrated some anti-H. pylori activity; however, the acetone extract was highly bactericidal.  At MIC<sub>90</sub>, the acetone extract exhibited inhibition at 2.5 to 5.0 mg/ml depending on the strain of H. pylori.   


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Revision as of 15:41, 25 March 2014

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A hematoxylin and eosin stain of Helicobacter pylori in the lumen of a gastric foveola. Photo by Ed Uthman1

For many individuals, Helicobacter pylori, gram-negative bacteria, reside in the stomach that many times lead to duodenal and peptic ulcers. Even though most individuals infected with H. pylori never show symptoms, this bacterium causes around 85 percent of all ulcers. Antibiotics, clarithromycin and amoxicillin, and a proton pump inhibitor are typically used to inhibit H. pylori growth to cure the ulcer. This triple therapy for the elimination of H. pylori faces uprising resistance problems demanding new antibiotic candidates. Alternative therapies from natural plants and foods are gaining popularity in order to find products to help combat the drug-resistant strands. Many studies have examined the antimicrobial activity of Pakistanian, Indian, and Iranian medicinal plants can be used as potential bactericidal agents for curing ulcers. Additionally, studies have found that fractional isolates of honey and turmeric are responsible for antibacterial activity. These compounds provide new lead molecules that can help eradicate H. pylori.

Resistant Strands of H. pylori


Bactericidal Activity of Plant Extracts

Many different extracts from plants have been shown to have antimicrobial activity. GutGard™ is a flavonoid rich extract of Glycyrrhiza glabra Linn, which is commonly known as Licorice. The company sells this product to those who suffer from gut and digestion related issues. Many studies have been conducted to determine the validity of GutGard™. Furthermore, different acetone and methanol extracts were taken from traditional medicinal plants to determine the minimal inhibitory concentration on different strands of H. pylori.


Flavonoid Extract

The minimal inhibitory concentration of the components in GutGard and three different positive controls. Data from Asha et al.


Glycyrrhiza glabra is normally found in the Mediterranean and parts of Asia. Many older civilizations used the root of this plant for its medicinal properties to cure stomach ulcers, kidney stones, skin eruptions, and more. Due to the increasing drug resistant strands of H. pylori, studies are trying to demonstrate and verify the antimicrobial activity of this natural plant. Through a microbroth dilution method, the minimum inhibitory concentrations against several variant strains of H. pylori were determined for GutGard™, glabrin, deglycyrrhizainated licorice (DGL), monoammonium glycyrrhizinate (MAG). Glabridin, a flavonoid rich extract of GutGard™, appeared to be the active ingredient causing anti-H. pylori activity.

GutGard’s™ mechanism of action is not quite confirmed, but through an in vitro study, GutGard™ demonstrated a protein synthesis inhibition via the reduction in (35)S methionine into H. pylori ATCC 700392 strain. Furthermore, this potential antibiotic exhibited an inhibitory effect on DNA gyrase and dihydrofolate reductase. Ciprofoxacin, levofoxacin, and fluroroquinolones, antibiotics that inhibit DNA gyrase, are being considered as possible drugs for the eradication of Helicobacter pylori. Thus, DNA gyrase may play an essential role in the growth and survival of H. pylori. Comparing the inhibition of DNA gyrase of GutGard™ to ciprofloxacin, GutGard™ had an IC50 of 4.40 μg/ml while the positive control, ciprofloxacin, showed an IC50 value of 12.31 ng/ml. If dihydrofolate reductase is blocked, the bacterial cells die because of its inhibition of DNA synthesis. When compared to the positive control methotrexate, GutGard™ was found to moderately inhibit H. pylori.

The chemical structures of different flavonoids. The flavonoids have very similar structures with only slight variations. The flavonoids compounds shown are a) naringenin, b) hesperidin, c) luteolin, d) quercetin, e) genkwanin, f) 7-O-butylnaringenin, g) kaempferol, h) apigenin, and i) hesperetin. Figure from Moon et al.



A double blind randomized study was conducted to evaluate the inhibitory effects of GutGard™. Participants were randomly placed into the placebo (n=52) and treatment (n=55) groups. Both groups orally received their respective drug once daily for 60 days. A 13C-urea breath test and Stool Antigen test were performed at days 0, 30, and 60 to measure the H. pylori levels in the stomach. Using the analysis of variance, chi-square, and Fisher’s exact probability test to compare the overall treatment conditions, the GutGard™ treatment group showed a statistically significant improvement in the management of H. pylori.

Even at a low stomach pH, flavonoids still seem to exhibit antibacterial activity. In general, flavonoids tend to have an antimicrobial effect against different H. pylori strains. The antibacterial effects of 7-O-Butylnaringenin, a novel flavonoid synthesized from citrus waste, and various natural flavonoids were studied. Hesperetin and naringenin exhibited the most antimicrobial effects for the natural flavonoids. However, 7-O-Butylnaringenin exhibited a higher inibiory effect against urease activity of H. pylori than the natural flavonoids. The morphological changes of H. pylori show that 7-O-buthylnaringen and hesperetin damage the bacterial cell membrane at 200 μM. This study shows how different natural products can be slightly modified to yield a compound with greater inhibitory potential.


Acetone and Methanol Extracts

Many plants from the Middle Eastern, Mediterranean, and Indian area have traditionally been used to treat common ailments. Acetone and methanol extracts from these plants possess some antibacterial properties against different strains of H. pylori. Using the agar dilution method, the minimum inhibitory concentrations of acetone, methanol, and water extracts were determined from various plants in the Punjab province of Pakistan. The extracts’ ability to inhibit H. pylori urease was assessed by the phenol red method. The methanol and acetone extracts from Acacia nilotica and Calotropis procera had significant antibacterial activity and urease inhibition but were less powerful compared to amoxicillin and clarithromycin. The extracts from Acacia nilotica and Calotropis procera exhibited different mechanisms of inhibition: competitive and mixed, respectively.

Combretum molle from South Africa has been widely used to treat gastric ulcers. The agar diffusion method showed the MIC of five different solvent extracts: acetone, ethanol, water, crude extract, and ethyl acetate. All the solvent extracts demonstrated some anti-H. pylori activity; however, the acetone extract was highly bactericidal. At MIC90, the acetone extract exhibited inhibition at 2.5 to 5.0 mg/ml depending on the strain of H. pylori.



Bactericidal Activity of Natural Foods


Include some current research in each topic, with at least one figure showing data.


Further Reading

[Sample link] Ebola Hemorrhagic Fever—Centers for Disease Control and Prevention, Special Pathogens Branch

References

[Sample reference] Takai, K., Sugai, A., Itoh, T., and Horikoshi, K. "Palaeococcus ferrophilus gen. nov., sp. nov., a barophilic, hyperthermophilic archaeon from a deep-sea hydrothermal vent chimney". International Journal of Systematic and Evolutionary Microbiology. 2000. Volume 50. p. 489-500.

Edited by (your name here), a student of Nora Sullivan in BIOL168L (Microbiology) in The Keck Science Department of the Claremont Colleges Spring 2014.