Green technologies for the valorization of medicinal plants residuals

The development of sustainable procedures for the valorization of industrial biomass wastes represents a major challenge for the scientific community1. Among biomasses, medicinal plants residuals could represent an attractive source of bioactive compounds. In this context, two residues from the industry of medicinal plant extracts, have been selected in our work namely: Cucurbita pepo L. seeds and Serenoa repens L. fruits, whose oils are commercialized for the treatment of genito-urinary tract pathologies. Supercritical CO2 technology (sc-CO2), has been employed as a highly selective “green” methodology that allows recovery of targeted compounds, without chemical degradation and limited operational costs, also enabling further extractions by tuning the physico-chemical parameters of the process affecting the supercritical fluid polarity (temperature, pressure and eventual presence of a co-solvent)2. Free and esterified fatty acids have been collected in mild conditions from the residual biomasses (mainly composed of linoleic, oleic and lauric acids) and are going to be converted into hydroxy fatty acids through biocatalysis; the improved hydrophilic character of hydroxy fatty acids make them appealing to cosmetics, paints and food industry3. Fractions enriched in isoprenes have been selectively obtained from sc-CO2 extracts by appropriate modulation of process parameters; indeed, consequently to initial exhaustion of the fatty acids content at mild conditions, increasing the CO2 density by tuning the adopted temperature and pressure, neutral fractions rich in sterols and polyprenols have been obtained. Polyprenols, a class of unsaturated isoprenic alcohols, could be of potential biological interest due to their proven pharmacological activities. Several studies in fact reveal that polyprenols can act as wide-spectrum antiviral agents and positively influence the immune system. 1 Tuck C.O. et al. Science, 337(6095), 695-699 2 Viganò J. et al. (2016) J Spercrit Fluits, 110, 1-10. 3 Cao Y. & Zhang X. (2013) Appl. Microbiol. Biotechnol., 97(8), 3323-3331