ABSTRACT
Six essential oils (EOs), Juniperus phoenicea (leaves and berries), Thymus capitatus, Lauris nobilis, Melaleuca armillaris, and Eucalyptus gracilis, were screened for their antioxidant and antihypertensive activity as well as their chemical compositions. We identified and quantified 24 compounds (representing 99.8% of total oil) for J. phoenicea leaves, 14 compounds (representing 98.8% of total oil) for J. phoenicea berries, 11 compounds (representing 99.6% of total oil) for T. capitatus, 32 compounds (representing 98.9% of total oil) for L. nobilis, 32 compounds (representing 98.7% of total oil) for M. armillaris, and 26 compounds (representing 99.3% of total oil) for E. gracilis. In the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay, the antioxidant activity was in the range of 0.59 to 2183.6 mg/L, whereas T. capitatus (1.24 ± 0.05 mg/L) gave the best activity in the 2,2'-azinobis-3-ethylbenzothiazoline-6-sulfonate assay. Antihypertensive activity was evaluated by testing the vasorelaxing capacity of EOs on rat aorta precontracted by phenylephrine (10(-6) M). T. capitatus and L. nobilis were most active for an antihypertensive activity (29 ± 3 and 59 ± 2 mg/L, respectively). Correlations between chemical composition or antioxidant activity and/or antihypertensive activity were studied. Significant correlation has been found for antihypertensive activity and p-cymene (R(2) = 0.86), ß-elemene (R(2) = 0.90), and ß-myrcene (R(2) = 0.76). A good correlation has been found between antihypertensive activity and antioxidant activity by DPPH assay (R(2) = 0.98). Antioxidant activity can contribute to the prevention of the increase of the blood pressure. According to the literature, no study has been reported until now of correlation between antihypertensive activity and antioxidant activity. Natural EOs can find its interest and application in a medicinal area.
Subject(s)
Antihypertensive Agents/pharmacology , Antioxidants/pharmacology , Oils, Volatile/pharmacology , Plant Extracts/pharmacology , Acyclic Monoterpenes , Animals , Antihypertensive Agents/chemistry , Antioxidants/chemistry , Biphenyl Compounds/chemistry , Blood Pressure/drug effects , Cymenes , Fruit/chemistry , Gas Chromatography-Mass Spectrometry , Juniperus/chemistry , Linear Models , Melaleuca/chemistry , Monoterpenes/pharmacology , Oils, Volatile/chemistry , Picrates/chemistry , Plant Extracts/chemistry , Plant Leaves/chemistry , Rats , Rats, Wistar , Sesquiterpenes/pharmacology , Thymus Plant/chemistry , Vasodilator Agents/chemistry , Vasodilator Agents/pharmacologyABSTRACT
Thymus capitatus Hoff. et Link. essential oil was constituted by thymol (89.06%) as a major component followed by p-cimene (5.04%) and γ-terpinene (3.19%) after analysis by gas chromatography-flame ionization detection and gas chromatography-mass spectrometry. The antioxidant activity assays of the essential oil used in the inhibition of the radical cation 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonate) and the free radical 2,2-diphenyl-1-picrylhydrazyl showed high 50% inhibitory concentration values of 1.24 ± 0.05 mg/L and 0.59 ± 0.02 mg/L, respectively. The essential oil of T. capitatus was tested for antimicrobial activity against Gram-positive bacteria (Salmonella analum, Listeria monocytogenes), Gram-negative bacteria (Escherchia coli, Klebsiella pneumoniae), fungi (Mucor ramamnianus, Aspergillus ochraceus), and yeast species (Saccharomyces cerevisiae, Candida albicans) using the agar well diffusion method. It seemed that L. monocytogenes, E. coli, and K. pneumoniae bacteria were inhibited by the essential oil tested. A strong activity was also observed against fungi and yeasts.
