Estudo químico do óleo essencial da parte aérea de Egletes viscosa (L.) Less

Abstract

Egletes viscosa (L.) Less, belonging to the Asteraceae family, is a herb popularly known as macela-da-terra or macela-do-sertão that occurs spontaneously near dams and lakes in the northeastern hinterland. Its floral chapters are used in traditional medicine for gastrointestinal problems. This part of the plant also yields a very aromatic essential oil, which has aroused the interest of the aroma and fragrance industry. However, although the aerial part also produces essential oil, it does not have any commercial appeal. In view of the scarcity of chemical studies on the aerial part of E. viscosa, the objective of the present work was to determine the yield and the chemical composition of the essential oil of the aerial parts and to compare them to those of the floral capitula. The investigated material was cultivated under controlled conditions and harvested after 5 months of planting. The floral chapters were manually separated from the aerial part (leaves and branches), dried in an air circulation oven and submitted to hydrodistillation in a Clevenger type apparatus. Essential oils obtained from shoots (OE-EVPA) and floral capitula (OE-EVCF) were analyzed by Gas Chromatography coupled to Mass Spectrometry (GC-MS). EO-EVPA was constituted by 9 constituents, being 29.43% monoterpenes, 4.3% sesquiterpenes and 36.81% diterpenes, while EO-EVCF was constituted by 8 constituents, being 5.79% monoterpenes and 94.21 % of monoterpenoids. The major compound for OE-EVPA was 9-cis-retinal and for OE-EVCF was cis-isopinocarveyl. In each of the parts, a new compound for the species was identified, namely sylvestrene and 9-cis-retinal. The essential oil of chemotype B, rich in cis-isopinocarveyl acetate, presented a content of 4.74% (m/v) for the floral portion and 0.25% (m/v) for the leaf portion, a difference of 19 times. Based on this work, there was a significant difference in the profile and yield between the two plant organs, which may have been amplified by the attack of insect pests on the plant, especially in the aerial part. Therefore, new analyzes will be necessary to determine the chemical composition of the essential oil of the aerial part in healthy plants of E. viscosa and, thus, to evaluate its possibility of industrial use, such as the floral capitula.