Stevia Extract: Antibacterial and Antioxidant Properties
Researchers from Egypt and Saudi Arabia published this study in the African Journal of Traditional, Complementary and Alternative Medicines, exploring stevia extract’s antibacterial and antioxidant effects.
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Stevia extract exhibits antibacterial activity, showing effectiveness against Staphylococcus aureus, Salmonella typhimurium, Escherichia coli, and Bacillus cereus.
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Demonstrates hepatoprotective effects, reducing oxidative stress and liver enzyme levels in rats exposed to CCl4.
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Rich in phenolic and flavonoid compounds, which contribute to its strong antioxidant capacity.
Overview
Stevia, a natural sweetener, is gaining recognition for its therapeutic potential beyond its use as a sugar substitute. Recent research has highlighted its antibacterial and antioxidant properties, particularly in the form of acetone extract. This extract has demonstrated efficacy in combating harmful bacteria and protecting the liver from oxidative damage.
Antibacterial Activity
The antibacterial activity of stevia extract was tested against five different bacterial strains. The study revealed that the acetone extract exhibited significant inhibitory effects on bacterial growth, while the aqueous extract showed no antibacterial activity.
Findings:
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The highest antibacterial activity was observed against Staphylococcus aureus at 50 mg/ml.
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Salmonella typhimurium was most affected at 20 mg/ml.
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Escherichia coli exhibited inhibition at 30 mg/ml.
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Bacillus cereus demonstrated susceptibility at 50 mg/ml.
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The antibacterial effects were attributed to the presence of monoterpenes and caryophyllene oxide.
These findings suggest that stevia acetone extract could serve as a natural antibacterial agent, with potential applications in food preservation and medicine.
Antioxidant and Hepatoprotective Effects
Stevia extract was also tested for its ability to protect against liver damage induced by carbon tetrachloride (CCl4), a known hepatotoxic agent. The results demonstrated a significant reduction in oxidative stress markers and an increase in antioxidant enzyme activity in treated groups.
Key Results:
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Liver Enzyme Reduction: The acetone extract significantly suppressed the elevation of serum ALT (p < 0.05) and AST (p < 0.001) levels caused by CCl4.
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Lipid Peroxidation: Stevia extract reduced malondialdehyde (MDA) levels, indicating decreased oxidative stress.
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Antioxidant Enzyme Activity: Treatment with stevia extract enhanced the levels of superoxide dismutase (SOD) and catalase (CAT), which protect cells from oxidative damage.
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Comparative Efficacy: The protective trial (administering stevia before CCl4 exposure) showed a more pronounced effect than the treatment trial (administering stevia after CCl4 exposure).
These findings suggest that stevia extract may be useful in preventing and mitigating oxidative liver damage, supporting its potential therapeutic role.
Phenolic and Flavonoid Content
Stevia extract's potent biological effects are attributed to its high phenolic and flavonoid content. The study measured these compounds in both aqueous and acetone extracts:
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Total Phenolic Content: 30 mg gallic acid/g in aqueous extract, 85 mg gallic acid/g in acetone extract.
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Total Flavonoid Content: 40 mg quercetin/g in aqueous extract, 80 mg quercetin/g in acetone extract.
The presence of these bioactive compounds contributes to stevia’s strong antioxidant capacity and potential health benefits.
Conclusion
The study concluded that acetone extract of stevia possesses significant antibacterial and hepatoprotective properties. Its ability to inhibit bacterial growth and reduce oxidative stress in the liver highlights its potential applications in medicine and health supplements. Given its natural origin and minimal side effects, stevia extract may serve as a promising alternative for antimicrobial and antioxidant therapies.
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