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

The suitability of supercritical carbon dioxide (scCO2) 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 antibacterial activity was evaluated against Escherichia coli in view of using the extracts as preservatives in cosmetic formulations. The composition and antibacterial activity of the scCO2 extracts were compared to the ones obtained by Soxhlet extraction with ethanol. The two methods resulted very different in terms of yields, selectivity, composition, and antibacterial properties of the extracts. In general, scCO2 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.