Optimization of a novel Renealmia ligulata (Zingiberaceae) essential oil extraction method through microwave-assisted hydrodistillation

Abstract

Renealmia is a tropical plant genus within the Zingiberaceae family. In tropical South America, Renealmia plants are known for their therapeutic uses against bone and muscle pain, colds, and to counteract snake bite symptoms. Despite the biomedical importance of Renealmia metabolites, the components of their essential oils (EO) have been scarcely studied, and a cause thereof is the lack of local efficient, inexpensive, and environmentally friendly EO extraction methods. This work addressed the optimization of an EO extraction method from the aerial parts and rhizomes of Renealmia ligulata plants based on microwave-assisted hydrodistillation (MAHD) with an ultrasound-assisted extraction (UAE) pretreatment. Three MAHD extraction variables (radiation power, radiation exposure length, and solvent volume) were studied on their own and in combination using a response surface analysis to determine the value combinations leading to optimal EO yields. The results showed that the best average extraction duration time was 42.5 min, combined with a radiation power of 765 W and a solvent volume 225.9 mL for 30 g of aerial part plant material or 799 W and 145 mL of solvent for 20 g of plant rhizomes. A GC-MS analysis of the obtained R. ligulata EOs revealed that their main component was epi-Eudesmol (28% in plant aerial parts and 13% in rhizomes), which is a molecule of interest considering its reported neuro-protective properties.