Antimicrobial activity of essential oils of some medicinal plants

Mehreshan T. El-Mokadem*, Azza M. Ghanem** and Khaled A. Shaheen* ; aboghalia, hoda 


The antimicrobial effect of four essential oils [Thymus vulgaris (thyme), Majorana hortensis (marjoram), Ocimum basilicum (basil) and Pelargonium graveolens (geranium) as well as commercial jojoba oil (Simmondsia chinensis)] were tested in vitro as antimicrobial agents against four Gram-ve bacteria (E. coli, Proteus vulgaris, Klebsiella sp. and Pseudomonas aeruginosa), five Gram +ve bacteria ( Staphylococcus aureus, Staph. faecalis, Staph. saprophyticus, Streptococcus pneumoniae, Strept. pyogenes) and one fungal strain (Candida albicans) isolated from patients. The results showed that thyme oil was the most effective, followed by marjoram, basil and geranium oils. However, jojoba oil had no effect. The minimum inhibitory concentration (MIC) of thyme oil to inhibit all test microorganisms varied from 0.16 to 0.64 mg/ ml medium. Candida albicans was inhibited at the lowest concentration (0.16 mg/ ml). Scanning electron microscopy (SEM) examination of C. albicans showed a great alteration in shape and size of the treated cells. The chemical composition of thyme oil by gas chromatography showed that it contained 33.6% thymol, 29.4% p-cymene and 5.4% carvacrol. The antimicrobial activity of the major constituents of thyme oil was also tested.Thymol and carvacrol were the most active as antimicrobial agents, while p- cymene was inactive.

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Keywords Antimicrobial activity - essential oils - medicinal plants –pathogenic bacteria – pathogenic fungi – MIC – SEM
Issue Date 2004
Journal N. Egypt. J. Microbiol. 

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