Chemical composition and pharmacological properties of the essential oils obtained seasonally from Lippia thymoides.

BACKGROUND

Lippia thymoides Mart. & Schauer (Verbenaceae) is used in folk medicine to treat wounds, fever, bronchitis, rheumatism, headaches, and weakness.

OBJECTIVE

This study determinates the chemical composition of essential oils from L. thymoides, obtained at during each of the four seasons and correlates with pharmacological properties.

METHODS

Essential oils were obtained by hydrodistillation and analyzed by gas chromatography coupled to mass spectroscopy (GC-MS). Antioxidant activity was determined by DPPH free radical scavenging and β-carotene bleaching methods. The antimicrobial assays were performed by minimum inhibitory concentration (MIC) and minimum microbicidal concentration (MMC) methods. Isolated rat aorta and uterus, and guinea-pig trachea were utilized to evaluate relaxant potential in pre-contracted smooth muscle.

CONCLUSIONS

Essential oils from leaves of L. thymoides had the sesquiterpene β-caryophyllene (17.22-26.27%) as the major constituent followed by borneol (4.45-7.36%), camphor (3.22-8.61%), camphene (2.64-5.66%), and germacrene D (4.72-6.18%). In vitro assays showed that these essential oils do not have antioxidant activity, have antimicrobial selectivity to Gram-positive bacteria Staphylococcus aureus (MIC = 0.004 mg/mL and MMC = 0.26-10.19 mg/mL) and Micrococcus luteus (MIC = 0.03 mg/mL and MMC = 8.43 mg/mL), relax isolated rat aorta (EC50 = 305-544 μg/mL, with endothelium; and EC50 = 150-283 μg/mL, without endothelium), and uterus (EC50 = 74-257 μg/mL), and minor potency, isolated guinea-pig trachea.

CONCLUSIONS

Lippia thymoides is a source of natural products of pharmaceutical interest, being necessary additional studies to determine the substances involved in the biological activities.