ABSTRACT
Resumen El presente estudio evaluó la actividad antimicrobiana de extractos y aceites esenciales de Lippia graveolens y Lippia alba, frente a nueve cepas de Aeromonas spp., aisladas de Oreochromis niloticus. Los extractos crudos se obtuvieron por la técnica de percolación y a través de la extracción de CO2 supercrítico, mientras que los aceites esenciales se realizaron mediante la técnica de hidrodestilación empleando un equipo Clevenger. La actividad antimicrobiana para cada extracto y aceite esencial se verificó mediante el método de difusión en disco a las 24 horas. El aceite esencial de L. graveolens mostró mayor efectividad para inhibir patógenos bacterianos de peces (100%), en comparación con los extractos. Se obtuvo un diámetro de inhibición que osciló entre 25,20 a 36,94 mm. Los extractos de fluido supercrítico y de la técnica de percolación con acetato de etilo y ciclohexano presentaron la misma efectividad (77,78%). El extracto crudo obtenido con etanol al 95% mostró efecto antimicrobiano limitado (22,22%), presentando el menor halo de inhibición (8,34 y 9,57 mm). Por otro parte, L. alba mostró menor actividad antibacteriana. El aceite esencial inhibió únicamente el 66,67% de las bacterias patógenas, presentando un halo de inhibición que oscila entre 10,68 a 16,29 mm. El resultado de este estudio indica que los aceites esenciales de L. graveolens y L. alba son una alternativa prometedora para el control del crecimiento de Aeromonas spp.
Abstract This study evaluated the antimicrobial activity of Lippia graveolens and Lippia alba extracts and essential oils against nine strains of Aeromonas spp., isolated from Oreochromis niloticus. The crude extracts were obtained by percolation technique and CO2 supercritical fluid extraction, while the essential oils by applying hydro-distillation technique using a Clevenger apparatus. The antimicrobial activity for each extract and essential oils was verified through the disc diffusion method at 24 hours. The essential oil of L. graveolens showed higher effectiveness to inhibit fish bacterial pathogens (100%) than the extracts, revealing an inhibition zone diameter that ranged from 25.20 - 36.94 mm. The extracts from supercritical fluid and from the percolation technique with ethyl acetate and cyclohexane presented the same effectiveness (77.78%). The crude extract obtained with ethanol 95% showed limited antimicrobial effect (22.22%), presenting the smallest inhibition zone (ranged from 8.34 to 9.57 mm). On the other hand, L. alba displayed a lower antibacterial activity, being the essential oil 66.67% effective, presenting an inhibition zone ranging between 10.68 to 16.29 mm. The result of this study indicates that essential oils from both L. graveolens and L. alba offer a promising alternative for the control of Aeromonas spp. growth.
Resumo Neste estudo avaliou-se a atividade antimicrobiana de extratos e óleos essenciais de Lippia graveolens e Lippia alba, contra nove cepas de Aeromonas spp., isoladas de Oreochromis niloticus. Os extratos brutos foram obtidos pela técnica de percolação e por extração supercrítica com CO2, enquanto os óleos essenciais foram obtidos por hidrodestilação em aparelho tipo Clevenger. A atividade antimicrobiana para cada extrato e óleo essencial foi verificada pelo método de disco-difusão em 24 horas. O óleo essencial de L. graveolens apresentou maior eficácia na inibição de patógenos bacterianos em peixes (100%), comparado aos extratos. Obteve-se um diâmetro de halo de inibição que variou entre 25,20 e 36,94 mm. Os extratos do fluido supercrítico e da percolação com acetato de etila e ciclohexano apresentaram a mesma eficácia (77,78%). O extrato bruto obtido com etanol 95% apresentou efeito antimicrobiano limitado (22,22%), apresentando o menor diámetro de halo de inibição (8,34 e 9,57 mm). Por outro lado, L. alba apresentou menor atividade antibacteriana. O óleo essencial inibiu apenas 66,67% das bactérias patogênicas, apresentando um halo de inibição que varia de 10,68 a 16,29 mm de diámetro. Os resultados deste estudo indica que os óleos essenciais de L. graveolens e L. alba são uma alternativa promissora para o controle do crescimento de Aeromonas spp.
ABSTRACT
Background: Pimenta dioica is a native tree of Central America, Southern Mexico, and the Caribbean used in traditional medicine. It grows in wet forests in the Guatemalan departments of Petén and Izabal. Since the plant is not being economically exploited in Guatemala, this study was aimed at determining the composition of the essential oil of P. dioica leaves and fruits and the antibacterial activity of the leaves in order to evaluate its possible use in health products. The essential oils of fruits and leaves are used as rubefacient, anti-inflammatory, carminative, antioxidant, and antiflatulent in different countries. Fruits and leaves of P. dioica from Izabal Department were collected in April 2014 and extracted by hydrodistillation method. The oils were analyzed by gas chromatography coupled with mass spectrometry (GC/MS). Yields of 1.02 ± 0.11% for dried leaves and 1.51 ± 0.26% for fruits were obtained. Eugenol was the main component (65.9-71.4%). The leaf oil showed growth inhibition against two Gram-positive and two Gram-negative bacteria. The authors consider that the tree's leaves can be evaluated as a source of ingredients for antiseptic products, and that it is important to evaluate other types of properties such as anti-inflammatory activity.
ABSTRACT
The composition and the antinociceptive activity of the essential oil of Stevia serrata Cav. from a population located in the west highlands of Guatemala were evaluated. A yield of 0.2% (w/w) of essential oil was obtained by hydrodistillation of the dried aerial parts of the plant. The essential oil analysed by GC-FID and GC-MS showed a high content of sesquiterpenoids, with chamazulene (60.1%) as the major component and 91.5% of the essential oil composition was identified. To evaluate antinociceptive activity in mice, the essential oil of S. serrata Cav. was administered as gavage, using three different doses. In the formalin test, the animals were pre-treated with oral doses of the essential oil before the administration of formalin. Oral administration of S. serrata Cav. essential oil produced a marked antinociceptive activity. Therefore, the plant could be domesticated as a source of essential oil rich in chamazulene for developing medicinal products.
