Effect of an Extractant on the Composition of the Lipophilic Constituents of the Extracts of Rhodiola rosea L. and on the Extracts’ Activity

The composition of the lipophilic components of the Rhodiola rosea L. plant was studied. Acidic and neutral components were identified by gas chromatography–mass spectrometry. With methyl-tert-butyl ether (MTBE) as an extractant instead of the volatile solvent diethyl ether, lipophilic extract was obtained. Methyl-tert-butyl ether used as an extraction solvent for raw materials has all the advantages of diethyl ether, being free of its disadvantages. It does not form peroxides or produce elevated partial gas pressure due to its higher boiling point. As a result, comparison with databases identified some triterpene, phenolic, and aliphatic acids with chain lengths 12 to 30 carbon atoms, including saturated, unsaturated, and dibasic acids. In addition to the components known from the literature, more than 50 triterpene and aliphatic compounds were detected in the unsaponifiable residue and acidic fractions for the first time. The hexane extract and the product obtained by the stepwise extraction by MTBE after the extraction of low-polarity compounds with hexane were investigated in a similar way. In the case of an extract obtained using MTBE after the extraction of low-polarity components with hexane, extraction of benzoic and cinnamic acids was more efficient compared to the exhaustive extraction of MTBE. These acids are absent from the hexane extract. Ethanol extraction was also carried out to test bioactivity: exhaustive and after hexane and MTBE extraction. Extracts obtained using MTBE and ethanol showed antiviral activity against the Ebola pseudovirus.