Investigations of natural products obtained by advanced and conventional extraction techniques

Abstract

Kumulative Dissertation aus acht Artikeln

Natural products are the most important precursors for drug production worldwide, and one of the biggest challenges of our generation is their sustainable production. For that purpose,various biological sources (flowers, leaves, fruits, herbs, stems, roots, algae) of secondary metabolites were investigated concerning different aspects: (i) Modern and conventional extraction methods as well as the development of new extraction strategies (ii) Investigation of agricultural waste (iii) Characterisation and analysis of secondary metabolites and their respective properties.A focus was placed on the investigation of hemp (Cannabis sativa L.). Therefore, a novel extraction process for cannabinoids based on ionic liquids and supercritical CO2(scCO2) was developed. Additionally, in the frame of the doctoral college Bioactive,cannabinoid yields obtained by pressurised liquid extraction (PLE) from hemp threshingresidues were analysed. Ultimately, the lesser exploited hemp roots were investigated fortriterpenoids and their respective antioxidative capacity and extracted by scCO2.Another major part of this thesis was dedicated to the investigation of polyphenols.By using has kap berries (Lonicera caerulea L.) as model plant, a new extraction process based on scCO2 and ethanol was developed to harvest anthocyanins, iridoids and fatty acids.Furthermore, the enzyme mix snailase was utilised to hydrolyse flavonoid glycosides from different plant extracts, and the hydrolysis efficiency was evaluated. Finally, grapevine (Vitisvinifera L.) shoot residue extracts, obtained by PLE, were investigated on polyphenols andtheir respective antioxidant power for a biorefinery concept in the framework of Bioactive.Carotenoids were the focus of two further cooperations in the frame between the two doctoral colleges Bioactive and Flower Power. To shed light on the colouration of burmarigold (Bidens ferulifolia) flowers, carotenoids were obtained by ultrasound-assisted extraction, identified and analysed as well as compared with polyphenols for a better understanding of the pigmentation. In addition, cultivated glacial algae (Tetraedronminimum) was analysed on carotenoids and their respective antioxidant capacity, among other parameters.