Given these considerations, the present study focused on the chemical composition of the essential oil obtained from the fresh ON1910 leaves of
L. grandis collected in Santarém, in the Brazilian state of Pará, and investigated their potential antimicrobial effects on clinically-important pathogenic micro-organisms. The dichloromethane used for analysis of the chemical components of the essential oil was supplied by Merck (Rio de Janeiro, Brazil) and distiled. For the antimicrobial assays, the culture media were obtained from Difco (São Paulo, Brazil). Tween 80, used in dilution series of the essential oil, and resazurin, an indicator of cell growth, were obtained from Vetec (Rio de Janeiro, Brazil). The standard Selleckchem 5-FU antimicrobial agents were supplied by Cecon (São Paulo, Brazil). Aerial parts of L. grandis were collected during the growing season at the Alter-do-Chão community in the municipality of Santarém, in the Brazilian state of Pará, in August, 2008. The position of the plant from which the specimens were obtained was determined using the Global Positioning System (GPS). The coordinates were 02°30’870”S, 54°56’416”W, and the altitude was approximately 52 m
above sea level. Reference specimens were deposited in the EMBRAPA-Eastern Amazonia herbarium under catalogue number IAN: 184688. The essential oil of L. grandis was obtained by hydrodistillation in a Clevenger apparatus, adapted to a 6000 ml round-bottom flask. A sample of the fresh
material (100 g) was immersed in distiled water at a ratio of 1:10 (w/v). Extraction time was set at 180 min, counting from the moment at selleck compound which the water in the flask began to boil. This procedure was repeated three times, rendering 2.7% of essential oil. The analysis of the chemical components of the essential oil of L. grandis was determined by gas chromatography-mass spectrometry (GC-MS) using a Shimadzu GC-17 AAF, V3, 230 LV apparatus. The samples were diluted in dichloromethane at a concentration of 10 mg/ml when 1 ml was injected in a system equipped with a HP5-MS (30 m × 0.25 mm × 0.25 um) column; injector split ratio of 1:50. Helium was used as carrier gas at a constant flow of 0.6 ml min−1. The injection port was set at 250 °C and the temperature cycle used was initially 50 °C, ramping at 3 °C/min for 3 min to a final temperature of 250 °C and kept for 15 min with the detector at 280 °C. MS operating parameters: transfer line temperature: 240 °C; electron impact ionization at 70 eV with mass scan range of 40–284 m/z at a sampling rate of 0.03 scan/s; ion source temperature: 200 °C.