the knowledge of chemical constituents of essential oils is of fundamental importance to the pharmaceutical , food , and perfumery industries . as the use of aromatic compounds requires detailed chemical characterization and evaluation of possible modifications within their compositions , which are due to the different geographical origins and/or climatic conditions and various population genetics that can lead to the formation of different chemotypes [ 1 , 2 ] . various studies involving the verbenaceae family have highlighted the importance of many species used within popular medicine by the presence of principle aromas [ 39 ] . it is worth noting that in this family , the species lippia sidoides , popularly known as alecrim - pimenta ,  native to the northeastern region of brazil and north of the state of minas gerais , is an aromatic species commonly used in the form of infusions and inhalations , allergic rhinitis , and in the treatment of vaginal , mouth , and throat infections . within the chemical components described of this species , thymol and carvacrol are major constituents of the essential oil [ 1113 ] , with a remarkable inhibitory activity regarding the development of microorganisms [ 1417 ] . moreover , the studies show variations in the concentration of thymol in different stages of the plant 's development . this work aims to determine the chemical composition of the essential oil of l. sidoides cultivated in an area of antropized cerrado in hidrolndia , gois , brazil . the leaves of lippia sidoides cham . were collected from three plants grown in the municipality of hidrolndia , gois , brazil ( altitude 835  m , 16 54 1.3 south , 49 15 35.2 west ) in august/2010 , both northwest minas gerais , brazil origin . marcos jos da silva , of departamento de biologia geral do instituto de cincias biolgicas / ufg , and vouchers were deposited in the herbarium of universidade federal de gois ( ufg ) under code number 45121 . essential oil was extracted by hydrodistillation in a clevenger - type apparatus for 2 hours from 50  g of powered leaves in 1000  ml of water . at the end of each distillation , the oils were measured in clevenger trap , collected , dried with anhydrous na2so4 , stored in hermetically sealed glass containers with rubber lids , covered with aluminum foil to protect the contents from light , and kept under refrigeration at 10c until used . the essential oil was submitted to gc / ms analysis performed on shimadzu qp5050a apparatus using a cbp-5 ( shimadzu ) fused silica capillary column ( 30  m  0.25  mm ; 0.25  m film thickness composed of 5% phenylmethylpolysiloxane ) and programmed temperature as follows : 60240c at 3c / min , then to 280c at 10c / min , ending with 10  min at 280c . the carrier gas was he at a flow rate of 1.0  ml / min and the split mode had a ratio of 1  :  20 . compounds were identified by computer search using digital libraries of mass spectral data   and by comparison of their retention indices and authentic mass spectra , relative to c8c32 n - alkane series   in a temperature - programmed run . the yield of lippia sidoides essential oil was 0.8% . within the identified components of the essential oil , the most abundant were oxygenated monoterpenes , followed by sesquiterpenes hydrocarbons ( table 1 ) . as described in table 1 and by chromatogram showed in figure 1 , 1,8 cineole , an oxygenated monoterpene was mostly constituent ( 26.67% ) , followed by isoborneol ( 14.60% ) and bornyl acetate ( 10.77% ) . in l. sidoides cultivated in minas gerais , brazil , the 1,8 cineole was also identified in lower concentrations ( 9.26% ) than in this work . 1,8 cineole was also identified in other species of its kind , such as lippia microphylla cham . n. e. brown [ 6 , 23 , 24 ] and lippia schomburgkiana schauer . the results found in this work for l. sidoides , cultivated in an area of anthropic bushland , differ from that presented in the literature , where the thymol and carvacrol appear as major components [ 1113 ] . what can be understood when considering that the environment of which the plant develops are factors such as temperature , relative humidity , exposure to the sun and wind , which exert a direct influence on the chemical composition of volatile oils [ 2 , 23 , 25 ] . alteration in the yield of the essential oils , as well as the quantity of chemical constituents can still be observed due to the different phases of the plant 's development [ 2 , 6 , 18 ] and at different times of the year [ 4 , 23 ] . qualitative and quantitative variations in the composition of the oils can also be observed in species that have chemotypes or chemical races , where botanically identical plants produce different chemical compounds , irrespective of their environment , as registered in l. alba , where three chemotypes from different regions and cultivated under the same conditions produce citral , carvone , and linalool , confirming that the variations occur in function of infra - specific variation . moreover , depending on the liability of the constituents of volatile oils , the method used to extract the essential oils could affect the identification [ 2 , 26 ] . the chemical composition of essential oil described in this paper differs from that described in the literature for l. sidoides found in its native environment , highlighting the need for further studies to assess the variation in chemical composition of vegetal species in different environments , especially those who may have biological activity .
several studies involving the family verbenaceae , occurring in the brazilian cerrado , have emphasized the popular use of many aromatic species . 
 we highlight the use of lippia sidoides cham . , 
 known as  alecrim pimenta ,  native to northeastern brazil and northern minas gerais . 
 leaves of this species were collected in antropized brazilian cerrado area , in hidrolndia , gois , and their essential oils were extracted by hydrodistillation in a clevenger - type apparatus and thereafter analyzed gc / ms . among the compounds identified in this study were the most abundant oxygenated monoterpenes , followed by sesquiterpenes hydrocarbons . 
 the oxygenated monoterpene 1,8-cineole was the major constituent followed by isoborneol and bornyl acetate . 
 the chemical composition of essential oil described in this paper differs from that described in the literature for l. sidoides found in its native environment , where the major constituents are thymol and carvacrol .