Development and optimization of extractive and analytical methods on Humulus lupulus L.

Humulus lupulus L. (cones) biosynthesises a specific variety of natural compounds with several applications in the food and pharmaceutical industries according to different access methods used.

This work focuses on the development of extractive methods with green solvents and transferable to other plant species on an industrial scale. All extractive techniques used were compared according to their yields, chemical composition such as total assays (polyphenol, flavonoid and chlorophyll), metabolite profile, LC- MS/MS quantification and molecular networks.

Classical extractive methods including maceration (SE) and ultrasound (UAE) were used along with alternative techniques using pressure (PLE) or microwaves (MAE), as well as other triphasic or combined extractions (SE+UAE). Ethanol was chosen as the reference solvent.

The use of ultrasound allowed increasing yield with reducing time in comparison with maceration. These results were clearly marked with PLE with 3 and 6-fold gains for yield and time.

The quantification of compounds showed that each extraction technique favours a type of products. The best content of α/β-bitter acids such as humulone and lupulone was obtained with PLE at 125°C. The xanthohumol content obtained by maceration is multiplied by 3 in MAE or by 5 with ASE. The determination of flavonoids and polyphenols demonstrated that MAE provides higher contents than other methods.

The use of pressure, microwaves or coupling methods strongly improves the yields (mass and molecules of interest) and LC-MS/MS allows us to follow different concentrations of metabolites and to choose the appropriate technique.

Publication History

Article published online:
16 November 2023