Fast ultrasound-assisted extraction of polar (phenols) and nonpolar (lipids) fractions in Heterotheca inuloides Cass.

Introduction - Heterotheca inuloides Cass., also known as "arnica", is used in traditional medicine in Mexico. Objective - Development of fast methods for the extraction of lipidic and phenolic fractions from arnica plants and their subsequent characterization. Methodology - Ultrasound was applied to accelerate extraction of the target compounds from this plant and reduce the use of organic solvents as compared with conventional methods. Gas chromatography-ion trap mass spectrometry and liquid chromatographywith diode-array detection were used for the characterization of the lipidic and phenolic fractions, respectively. Results - Under optimal extraction conditions, 9 and 55 min were necessary to complete extraction of the lipidic and phenolic fractions, respectively. The fatty acids present at the highest concentrations in H. inuloides were eicosatetraenoic n3 (24.6 μg/g), cis-9-hexadecenoic n7 (23.1 μg/g), exacosanoic (22.7 μg/g) and cis-9-octadecenoic acid (21.3 μg/g), while the rest were in the range 7.6-1.3 μg/g. The most concentrated phenols were guaiacol (41.5 μg/g), catechin (38.7 μg/g), ellagic acid (35.9 μg/g), carbolic acid (24.2 μg/g) and p-coumaric acid (19.5 μg/g), while the rest were in the range 5.1-0.4 μg/g. Conclusion - Ultrasound reduces the time necessary to complete the extraction 160 and 26 times, the extraction volume 2.5 and 4 times, and increases the extraction efficiency 5 and 3 times for lipidic and phenolic fractions, respectively, in comparison with conventional extraction methods. In addition, the characterization of the lipidic and phenolic fractions constitutes a first approach to the H. inuloides metabolome.