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

CONTEXT: 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. MATERIALS AND 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 ß-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. RESULTS AND DISCUSSION: Essential oils from leaves of L. thymoides had the sesquiterpene ß-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.

Atividade antimicrobiana de méis de cinco espécies de abelhas brasileiras sem ferrão / Antimicrobial activity of honey from five species of Brazilian stingless bees

A atividade antimicrobiana de méis produzidos por Melipona asilvai, Melipona quadrifasciata anthidioides, Friseomelita doederleinei, Tetragonisca angustula e Plebeia sp. foi investigada. O teste de difusão em poço demonstrou que todos os méis tem ação antibacteriana frente a Staphylococcus aureus, mas somente as amostras produzidas por M. quadrifasciata anthidioides e F. doederleinei inibiram o crescimento de Escherichia coli. No ensaio de determinação da concentração inibitória mínima, os méis de M. asilvai, M. quadrifasciata anthidioides, F. doederleinei e T. angustula foram mais ativos que os de Plebeia sp. frente a S. aureus e E. coli. Os micro-organismos Pseudomonas aeruginosa e Candida albicans foram resistentes a todos os méis em ambos ensaios. Os méis foram mais efetivos contra as bactérias do que frente a uma solução de açúcar, sugerindo que o mecanismo de inibição do crescimento bacteriano não está somente relacionado ao efeito osmótico. Os resultados obtidos podem explicar o uso medicinal desses méis em doenças bacterianas.

The antimicrobial activity of honey produced by Melipona asilvai, Melipona quadrifasciata anthidioides, Friseomelita doederleinei, Tetragonisca angustula and Plebeia sp. were investigated. The agar well diffusion assay demonstrated that all honeys had antibacterial activity against Staphylococcus aureus, but only the samples from M. quadrifasciata anthidioides and F. doederleinei inhibited the growth of Escherichia coli. In the Minimum Inhibitory Concentration determination assay, M. asilvai, M. quadrifasciata anthidioides, F. doederleinei and T. angustula honeys were more active than that from Plebeia sp. for S. aureus and E. coli. The microorganisms Pseudomonas aeruginosa and Candida albicans were resistant to the all native stingless bee honeys in both assays. Honeys were more effective against bacteria than a sugar solution, suggesting that the mechanism for bacterial growth inhibition is not only related to the osmotic effect. The results of antimicrobial activity may explain the popular medicinal use of these honeys in bacterial diseases.