Antimicrobial potency of red and yellow varieties of grapefruit (Citrus Paradisi Macfad) grown in Jordan

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Malek A. Zihlif
Fatima Afifi


grapefruit, antimicrobial, microorganisms, Jordan


Introduction: Worldwide, grapefruit is known to have medicinal values with antimicrobial, anti-inflammatory, antioxidant, and astringent propensities. Only a few researchers studied its antibacterial effects underlining the efficacy of the flavonoids extracted from the grapefruit peels against gram-positive and negative bacteria. Aims: The purpose of this work was to evaluate the antibacterial activity of the grapefruit water and ethanol extracts and their furanocoumarins against three common infectious bacteria and their multi-drug resistant clinical isolates. Methods: Antimicrobial activity of 4 different grapefruit extracts (Red-Ethanol, Yellow-Ethanol, Red-n-Hexane, Yellow-n-Hexane) from 2 different varieties (Red & Yellow) along with 4 of its active materials (naringin X, Bergaptol, Bergapten, Bergamottin) have been evaluated in vitro against 7 different bacteria that are frequently incriminated in human infection four of which were ATCC (Salmonella paratyphi, E.coli, Staphylococcus aureus, Pseudomonas) and three clinical bacteria (Pseudomonas aeruginosa drugs sensitive, Klebsiellas pneumonia multi-drug resistant, Pseudomonas aeruginosa multi-drug resistant) by assessing the minimum inhibitory concentration (MIC), using the microdilution method to test the microorganisms. Results: Most of the grapefruit’s tested extracts showed great activity level, including the active materials (Furanocoumarins) of the grapefruit, which showed a strong level of antimicrobial activity against the tested microorganisms, especially against the gram-negatives. Conclusions: The results obtained from this study confirm that the grapefruit extracts had a significant antimicrobial effect on the tested microorganisms, especially the Red-Ethanol extract, which had more activity against gram-negative bacteria, including E.coli, Pseudomonas as well as Pseudomonas aeruginosa drugs sensitive.

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