Pressurized Natural Deep Eutectic Solvent Extraction of Galanthamine and related alkaloids from Narcissus pseudonarcissus

Abstract

The isolation of a compound from a natural source involves many organic and mostly toxic solvents for extraction and purification. Natural Deep Eutectic Solvents (NADES) have been shown to be efficient options for the extraction of natural products. They have the advantage of being composed of abundantly available common primary metabolites, being non-toxic and environmentally safe solvents. The aim of this study was to develop a NADES-based extraction method for galanthamine, an important therapeutic agent for the treatment of Alzheimer’s disease. This alkaloid can be produced by synthesis or by extraction from Narcissus bulbs. To develop an efficient extraction method a number of different NADES was first tested for their solubilization capacity of the galanthamine bromide salt. Promising results were obtained for ionic liquids, as well as some amphoteric and acidic NADES. In a two-cycle extraction process the best solvents were tested for the extraction of galanthamine from bulbs. The ionic liquids produced poor yields, and the best results were obtained with some acid and sugar mixtures, among which malic acid – sucrose – water (1:1:5) proved to be the best, showing similar yields to that of the exhaustive Soxhlet extraction with methanol. Furthermore, the NADES was more selective for galanthamine.