Effect of drying temperature on yield and phytochemical quality of essential oil extracted from Mikania laevigata (Guaco) leaves / Efeito da temperatura de secagem sobre o rendimento e qualidade fitoquímica de óleo essencial extraído de folhas de Mikania laevigata (Guaco)

Abstract

Mikania laevigata Sch. Bip. ex Baker, Asteraceae, commonly known as the guaco, is medicinal species native to Brazil. Among the critical points of post-harvest processing of medicinal species, the drying temperature must be considered, because its can interfere in the yield and phytochemical quality of plant material, and, consequently, in the therapeutic action. The effect of the drying temperature was evaluated on the yield and phytochemical quality of the essential oil extracted from M. laevigata leaves. The cultivation was carried out in an organic system and using the select genotype (Cenargen) for this region. The leaves were harvested and immediately submitted to drying process at 40, 50 and 60 °C. The essential oils were extracted by hydrodistillation in Clevenger apparatus and the chemical constituents was evaluated using gas chromatography coupled to the mass spectrophotometer (CG-MS). There was a reduction in the essential oil yield (p <0.05) with increasing drying temperature. However, at 60 ºC there was a higher concentration of coumarin to which the bronchodilator and expectorant action is attributed. Therefore, we recommended dry the M. laevigata leaves at 60 ºC to obtain the highest coumarin content and guarantee the bronchodilator and expectorant therapeutic effect