Antimicrobial activity of carnosic acid isolated from Rosmarinus officinalis L. leaves

Abbas Al-Bayati, Firas

	Antimicrobial activity of carnosic acid isolated from Rosmarinus officinalis L. leaves
Tikrit Journal of Pure Science
Article 1, Volume 16, Issue 4, 2011, Pages 6-11
Author
Firas Abbas Al-Bayati
Abstract
Carnosic acid C20H28O4, the major compound in Rosmarinus officinalis L. (Lamiaceae) leaves was isolated and purified through silica gel column chromatography and detected on TLC plates in comparison with standard carnosic acid that served as positive control. Moreover, FTIR spectrometry and HPLC analysis were used to confirm the purity and identity of carnosic acid. The separated acid was investigated for its antimicrobial activity against six selected pathogenic microorganisms: Staphylococcus aureus, Bacillus cereus, Escherichia coli, Salmonella typhimurium, Pseudomonas aeruginosa and the yeast Candida albicans. Carnosic acid at different concentrations (5, 2.5, 1.25 and 0.62 mg/ml) was active against all tested microorganisms. High inhibitory effects were observed against Bacillus cereus and Staphylococcus aureus (zone of inhibition: 21.7 and 20.3 mm respectively) using the disc diffusion method. The minimal inhibitory concentration (MIC) of carnosic acid was determined using a broth microdilution method in 96-well microtiter plates. MIC values ranged from 15.6 to 125.0 μg/ml, and the highest value was recorded against Bacillus cereus and Staphylococcus aureus (MIC 15.6 μg/ml), followed by Escherichia coli, Salmonella typhimurium and Pseudomonas aeruginosa respectively. Moreover, carnosic acid observed good antifungal activity against the yeast Candida albicans (zone of inhibition range: 11.2-17.4mm; MIC: 125.0 μg/ml).

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