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Comparative antibacterial and antifungal effects of some phenolic compounds
N H Aziz1, S E Farag, L A Mousa
1National Centre for Radiation Research and Technology, Nasr City, Cairo, Egypt.
Abstract:
The antimicrobial potential of eight phenolic compounds isolated from olive cake was tested against the growth of Escherichia coli, Klebsiella pneumoniae, Bacillus cereus, Aspergillus flavus and Aspergillus parasiticus. The phenolic compounds included p-hydroxy benzoic, vanillic, caffeic, protocatechuic, syringic, and p-coumaric acids, oleuropein and quercetin. Caffeic and protocatechuic acids (0.3 mg/ml) inhibited the growth of E. coli and K. pneumoniae. The same compounds apart from syringic acid (0.5 mg/ml) completely inhibited the growth of B. cereus. Oleuropein, and p-hydroxy benzoic, vanillic and p-coumaric acids (0.4 mg/ml) completely inhibited the growth of E. coli, K. pneumoniae and B. cereus. Vanillic and caffeic acids (0.2 mg/ml) completely inhibited the growth and aflatoxin production by both A. flavus and A. parasiticus, whereas the complete inhibition of the moulds was attained with 0.3 mg/ml p-hydroxy benzoic, protocatechuic, syringic, and p-coumaric acids and quercetin.
Insights
Olive cake phenolic compounds show significant antimicrobial activity. Certain compounds effectively inhibited the growth of bacteria like Escherichia coli and fungi such as Aspergillus flavus.
Area of Science:
- Food Science
- Microbiology
- Natural Products Chemistry
Background:
- Olive cake is a byproduct of olive oil production, rich in phenolic compounds.
- Phenolic compounds are known for their diverse biological activities, including antimicrobial properties.
- Investigating the antimicrobial potential of olive cake phenolics can lead to novel applications.
Purpose of the Study:
- To evaluate the antimicrobial activity of eight phenolic compounds isolated from olive cake.
- To determine the efficacy of these compounds against specific bacterial and fungal strains.
- To identify which phenolic compounds are most effective and at what concentrations.
Main Methods:
- Isolation of eight phenolic compounds from olive cake: p-hydroxy benzoic acid, vanillic acid, caffeic acid, protocatechuic acid, syringic acid, p-coumaric acid, oleuropein, and quercetin.
- Testing the antimicrobial potential against Escherichia coli, Klebsiella pneumoniae, Bacillus cereus, Aspergillus flavus, and Aspergillus parasiticus.
- Determining the minimum inhibitory concentrations (MICs) for each compound against the tested microorganisms.
Main Results:
- Caffeic and protocatechuic acids inhibited E. coli and K. pneumoniae at 0.3 mg/ml.
- Vanillic, caffeic, oleuropein, p-hydroxy benzoic, and p-coumaric acids showed complete inhibition of E. coli, K. pneumoniae, and B. cereus at 0.4 mg/ml.
- Vanillic and caffeic acids inhibited A. flavus and A. parasiticus growth and aflatoxin production at 0.2 mg/ml, while other phenolics achieved this at 0.3 mg/ml.
Conclusions:
- Phenolic compounds from olive cake possess significant antimicrobial properties against tested bacteria and fungi.
- Specific compounds like vanillic and caffeic acids demonstrate potent inhibitory effects on both bacterial growth and fungal aflatoxin production.
- Olive cake is a valuable source of natural antimicrobial agents with potential applications in food preservation and safety.
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