Novel Methods for the Extraction of Galanthamine from Narcissus pseudonarcissus Bulbs

A large number of studies on Narcissus, a member of the Amaryllidaceae family, have been published. In particular on Narcissus species, their alkaloids content, their structures including with MS-fragmentation patterns, their preparative extractions, and the analysis of these compounds covering GC-MS, LC-MS, HPLC-DAD, as well as 1H-NMR have been intensively reported. However, aspects on pre-analytical steps, extraction in bulk quantities using green alternatives solvent have not been reported widely, hence leaving space for investigation. In this thesis, the sustainable production of galanthamine from Narcissus pseudonarcissus cv. Carlton bulbs, a relatively cheap biological left-over matrix from the agricultural-flower industry, was investigated within joint collaboration between the former Process Equipment Laboratory, and the Biotechnology department of Delft University of Technology, and the Natural Product groups of Institute Biology of Leiden University. The aim of the project was gaining insight into the extraction of N. pseudonarcissus alkaloids, especially galanthamine, by means of using green solvents instead of using volatile organic solvents (VOCs) as in the conventional process. Both supercritical fluid (SCF) (c.q. supercritical carbon dioxide) and natural deep eutectic solvents (NADES) which are recently considered as green solvents were applied. Classical alkaloids extraction methods by means of acid-base purification steps of alkaloids as well as an exhaustive Soxhlet extraction as a benchmarking method were also conducted for comparison. It was investigated whether the proposed method provides high yield and selectivity of the targeted compound. The described study must be considered as the first step for further studies on the commercial production of galanthamine from the biological matrix; to address the challenges met in the bulk quantity production of galanthamine, a N. pseudonarcissus alkaloid. Prior to doing the supercritical CO2 (scCO2) extraction, a literature study was carried out. According to the previous studies on the secondary metabolites (SMs) extractions by using scCO2, many aspects were found essential for the success of the extractions process. They are divided mainly into pre-extraction, extraction, and postextraction step, particularly when dealing with the plant’s matrices. Grinding and impregnation of the grinded material are important in this step as well as the drying of the material to keep the water level around 5-10% of dry weight. The selectivity of alkaloids is largely affected by adjusting the CO2 density which can be tuned by controlling the pressure and temperature of the scCO2 as well as by modifier addition. In the extraction step, particle size, porosity, contact surface area, and solubility of target compounds combining with the process systems, i.e. batch or continuous, play a major role. An integrated process including scCO2 extraction as well as fractionation in the postextraction step seems to be a promising strategy to enhance the yield and selectivity of targeted compounds. ..