The Modulation of PCSK9 and LDLR by Supercritical CO(2) Extracts of Mentha longifolia and Isolated Piperitone Oxide, an In Vitro Study

In the present study the ability of supercritical carbon dioxide (SCO(2)) extracts of M. longifolia L. leaves to modulate low-density lipoprotein receptor (LDLR) and proprotein convertase subtilisin/kexin type 9 (PCSK9) expression was evaluated in cultured human hepatoma cell lines Huh7 and HepG2. Two SCO(2) extracts, one oil (ML-SCO(2)) and a semisolid (MW-SCO(2)), were subjected to detailed chemical characterization by mono- and bidimensional nuclear magnetic resonance (1D, 2D-NMR), gas chromatography coupled with mass spectrometry (GC-MS) and liquid chromatography coupled with mass spectrometry (LC-MS). Chemical analysis revealed significant amounts of fatty acids, phytosterols and terpenoids. ML-SCO(2) was able to induce LDLR expression at a dose of 60 µg/mL in HuH7 and HepG2 cell lines. Furthermore, ML-SCO(2) reduced PCSK9 secretion in a concentration-dependent manner in both cell lines. Piperitone oxide, the most abundant compound of the volatile constituent of ML-SCO(2) (27% w/w), was isolated and tested for the same targets, showing a very effective reduction of PCSK9 expression. The overall results revealed the opportunity to obtain a new nutraceutical ingredient with a high amount of phytosterols and terpenoids using the SCO(2) extraction of M. longifolia L., a very well-known botanical species used as food. Furthermore, for the first time we report the high activity of piperitone oxide in the reduction of PCSK9 expression.