Shades of red: Comparative study on supercritical CO2 extraction of lycopene-rich oleoresins from gac, tomato and watermelon fruits and effect of the alpha-cyclodextrin clathrated extracts on cultured lung adenocarcinoma cells' viability

Lycopene is a red carotenoid thought effective in preventing some types of cancers and modulating immune and inflammatory responses. Though some fruits share the common feature of synthesizing and storing lycopene as main carotenoid within chromoplasts, they significantly differ in the lipophilic phytocomplex. The purpose of this work was: i) to extract solvent-free lycopene-rich oleoresins from gac, tomato and watermelon ripe-fruits by supercritical CO2 suitable for functional food and nutraceutical formulations; ii) characterize the oleoresins with respect to carotenoids, tocochromanols, lipids, metals and antioxidant activity; iii) prepare stable aqueous suspensions through oleoresin clathration into alpha-cyclodextrins (alpha-CDs); iv) investigate the effect of each lycopene-containing suspension on viability of human lung adenocarcinoma cells. The results showed that all oleoresins represent a safe added-value source of lycopene characterized by high lipophilic antioxidant activity, improved by the synergy with other biomolecules. Interestingly, when administered at identical concentrations (0.5-10 mu M) of lycopene, the extracts showed conflicting behaviors: gac and tomato suspensions significantly increased cell viability, whereas watermelon oleoresin/alpha-CD suspension significantly decreased cell viability. Although further studies are required, this research suggests a fundamental role of phytocomplex in affecting the responses of cancer cell survival to the in vitro administration of lycopene.