Recovery of essential oils from the withered flowers of Magnolia soulangeana Soul.-Bod. by microwave-assisted hydrodistillation with uniform heating and its new application in the hypolipidemic field

Abstract

This study innovatively designed a microwave-assisted hydrodistillation method with uniform heating to extract the essential oil from the withered flowers of Magnolia soulangeana Soul.-Bod., in which the addition of the rotating unit is applied to improve the uneven heating of plant materials caused by the fixation of the flask and the energy point in the microwave system, and the soaking pretreatment unit is used to fully swell the plant cells and accelerate the overflow of essential oils. Meanwhile, the significance of the independent variables that may affect the yield of essential oil and the optimal conditions were screened and optimized by means of response surface methodology, and the results showed that the introduction of the rotation unit and soaking pretreatment unit increased the yield of essential oil by 16.67% and 20%, respectively, which highly promoted the increase of the yield and extraction rate of essential oil. Moreover, the samples obtained by this new method are rich in terpene compounds, such as eucalyptol, δ-cadinene, α-muurolene, and germacrene D, which is consistent with the results of traditional hydrodistillation, and also further illustrates the safety of this method. And the hypolipidemic activity of these compounds was also verified, and the main compound in the essential oil that exerts the hypolipidemic activity may be δ-cadinene, and its possible target for reducing total cholesterol content is Niemann-Pick C1-like 1. In addition, this study also shows that this new method shows lower energy consumption and environmental pressure and is very promising to replace the existing method for the large-scale preparation of essential oils.