Environmentally benign supercritical CO₂ extraction of galanthamine from floricultural crop waste of Narcissus pseudonarcissus

The influence of diverse factors on the supercritical fluid extraction (SFE) with supercritical CO₂ (scCO₂) of galanthamine from bulbs of Narcissus pseudonarcissus cv. Carlton was investigated. The parameters that were studied were CO₂ density (temperature and pressure), flow rate and plant material particle size and pre-treatment. The highest yield (303 μg/g) was achieved by extracting 53-1000 μm particle-size powdered dried bulb material moistened with NH₄OH (25%, v/v) at 70 °C, 220 bar (690 kg/m³) for 3 h. Other N. pseudonarcissus alkaloids such as O-methyllycorenine and haemanthamine were also obtained. N. pseudonarcissus alkaloids as free bases are highly soluble in CO₂ at a high pH as opposed to the slightly soluble salt form in which they are generally found in plants. Therefore, plant material pre-treatment with a base is an essential step for galanthamine extraction. Scanning electron microscope (SEM) results also revealed that the desorption of N. pseudonarcissus alkaloids from the plant material rather than the solubility of the alkaloids in the scCO₂ plays a major role in this scCO₂ extraction. This extraction method has a good potential for industrial application.