SEASONAL CHEMICAL COMPOSITIONS OF THE ESSENTIAL OILS OF TWOEugenia SPECIES AND THEIR ACARICIDAL PROPERTIES

http://dx.doi.org/10.5935/0100-4042.20150161 Quim. Nova, Vol. 39, No. 1, 38-43, 2016 Artigo SEASONAL CHEMICAL COMPOSITIONS OF THE ESSENTIAL OILS OF TWO Eugenia SPECIES AND THEIR ACARICIDAL PROPERTIES Paulo H. S. Ribeiroa, Maria L. dos Santosa,*, Claudio A. G. da Camarab, Flávia S. Bornb and Christopher W. Faggc a Instituto de Química, Universidade de Brasília, 70919-970 Brasília – DF, Brasil b Departamento de Química, Universidade Federal Rural de Pernambuco, 52171-900 Recife – PE, Brasil c Faculdade de Ceilândia, Universidade de Brasília, 72220-140 Brasília – DF, Brasil Recebido em 13/06/2015; aceito em 03/09/2015; publicado na web em 26/10/2015 The leaf essential oils of Eugenia lutescens Cambess and Eugenia langsdorffii O. Berg, collected in the rainy (RS) and dry seasons (DS), were extracted by hydrodistillation and then characterized by a gas chromatography-flame ionization detector and a gas chromatography-mass spectrometer. The potential acaricidal activity and oviposition deterrence of these oils were evaluated against Tetranychus urticae. The oil yields were higher in the RS for E. lutescens, while those for E. langsdorffii were higher in the DS. α-Pinene and β-pinene were determined to be the major constituents of the oils from E. lutescens, while bicyclogermacrene, spathulenol, and β-caryophyllene predominated in E. langsdorffii. Seasonal variations in the oils were primarily related to chemical diversity, and E. lutescens was more affected than was E. langsdorffii. The E. langsdorffii oil collected in the DS was most toxic to the spider mite, while the oils of E. lutescens and E. langsdorffii collected in the RS drastically reduced its egg quantities. This study successfully determined the periods of greater oil production and acaricidal activity. Keywords: Eugenia lutescens; Eugenia langsdorffii; seasonal variations; acaricidal properties; Tetranychus urticae. INTRODUCTION With approximately 2 million km2 the Brazilian savanna, hereafter called cerrado, represents about 23% of the country, extending over ten states and the Federal District and features as the second greatest biome after the Amazonian forest.1 Brazilian cerrado is the richest tropical savanna in the world, with over 12,000 flowering plants recorded,2 and one of the 25 global biodiversity hotspots for priority conservation,3 statistics which have been stimulating the prospection of chemical compounds of economic value for medicinal, 4,5 agricultural and other applications.5 Eugenia species (Myrtaceae) have been found in floristic and phytosociological studies in various forest in cerrado including the southeast of Brazil.6 Their plants, usually appreciated for its edible fruits, also show high levels of essential oils characterized by chemical diversity (e.g. sesquiterpenes, monoterpenes and phenylpropanoids) and a wide range of biological properties.7 For instance several studies with essential oils from Eugenia species have shown therapeutic potential as anticonvulsant,8 anti-inflammatory,9 antinociceptive,9,10 hypothermic,10 antioxidant and antimicrobial,11 but none of them have investigated Eugenia langsdorffii O. Berg and Eugenia lutescens Cambess. In addition, there are some records associated to the activity of essential oils from Eugenia genus against several arthropods. For example, the insecticidal and acaricidal properties of the E. uniflora and E. caryophyllata essential oils against the maize weevil (Sitophilus zeamais); 12 and the dust mite (Dermatophagoides farinae)13 and spotted spider mite (Tetranychus urticae).14 The spotted spider mite is one of the most important agricultural pests that produce major losses in cultivated crops from North to South Brazil. The principal form of control of this pest involves the indiscriminate use of acaricides, associated with the presence of residues in foods, contamination of the environment and selection of more resistant populations, which then require greater number of applications. *e-mail: Aiming to establish a rational control, with low toxicity to mammals and a reduced persistence in the environment, the use of essential oils as an active ingredient in formulations for the control of agricultural pests is an excellent alternative to synthetic pesticides, given the chemical diversity of the oils, which act at the same time in various areas of the insect, reducing the risk of the pest acquiring resistance.15 According to a bibliographic survey, no study has been undertaken with the essential oil of E. lutescens against spider mite. While our research group has published the chemical composition of the leaf essential oil of E. langsdorffii reporting that epi-longipinanol (13.6 ± 0.1%) and g-eudesmol (12.3 ± 0.2%)16 are the major constituents and promising products for the control of T. urticae rather than the fruit oil, no study has been undertaken confirming if the chemical profile of the E. langsdorffii leaf oil varies seasonally and whether it affects its acaricidal properties. Continuing ongoing studies on the chemical and biological potential of aromatic plants that occur in the cerrado of Brazil and looking for new products with acaricidal properties, the purpose of this work is to investigate the seasonal variation in yields and micro molecular composition of leaf essential oils from E. lutescens and E. langsdorffii, collected in two seasons, and correlating their chemical profile with acaricidal property on the spider mite (Tetranychus urticae). EXPERIMENTAL Collection of plant material The fresh leaves from E. lutescens (15°45’56.2”S 47°51’26.1”W) and E. langsdorffii (15°46’23.5”S 47°51’58.2”W) were collected in the morning during two periods of 2012 (March and August) in the Cerrado biome around the campus Darcy Ribeiro of the University of Brasília (UnB), Federal District. The plants were identified by the botanist Jair Faria Jn of the Botany Department, UnB. Voucher specimens were deposited in the UnB herbarium (UB) under the numbers: Fagg CW 2189 (E. lutescens) and Faria Jn JEQ & Fagg CW 918 (E. langsdorffii). Vol. 39, No. 1 Seasonal chemical compositions of the essential oils of two Eugenia species and their acaricidal properties Isolation of the essential oil The essential oils (OE’s) from fresh leaves of E. lutescens and E. langsdorffii (100 g) were extracted using a modified Clevenger-type apparatus by hydrodistillation for 2 h. The oil layer was separated and dried over anhydrous sodium sulfate, stored in hermetically sealed glass vials, and kept under refrigeration at +5 °C until the acaricidal assays and chemical analysis. Total oil yield was expressed as percentages (g/100 g of fresh plant material). All experiments were carried out in triplicate. Chemicals Monoterpenes and sesquiterpenes used for identifications of volatile components (β-pinene, α-pinene, limonene, α-terpineol, β-caryophyllene and its oxide, aromadendrene, α-humulene and valencene) and eugenol used in the bioassay as a positive contro (...truncated)