Supercritical CO2 extraction of natural antibacterials from low value weeds and agro-waste

The suitability of supercritical carbon dioxide (scCO 2 ) to extract cosmetic-friendly preservatives from low value weeds and agro-waste was investigated. The essential oils extracted from Humulus Lupulus and Datura Stramonium (leaves and flowers) were analysed in search for potential antibacterial compounds. Their anti- bacterial activity was evaluated against Escherichia coli in view of using the extracts as preservatives in cosmetic formulations. The composition and antibacterial activity of the scCO 2 extracts were compared to the ones obtained by Soxhlet extraction with ethanol. The two methods resulted very different in terms of yields, selectivity, com- position, and antibacterial properties of the extracts. In general, scCO 2 was better for the recovery of preservative compounds since it led to the selective extraction of volatile oils composed mainly by terpenes, terpenoids, fatty acids, and bitter acids.