Costunolide and parthenolide: Novel blood-brain barrier permeable sesquiterpene lactones to improve barrier tightness.

Sesquiterpene lactones - such as those found in chicory - are considered promising bioactive compounds. These small molecules have shown several health benefits for various diseases, including brain disorders. However, it is unknown whether these compounds can cross the blood-brain barrier (BBB), and which could be the effects on brain microvascular endothelial cells. We show that six sesquiterpene lactones evaluated in an in vitro model of the BBB have different capacities to be transported through the barrier. Costunolide presented more than 20 % of transport while lactucin, 11β-13-dihydrolactucin, 11β-13-dihydrolactucopicrin, and parthenolide presented between 10 % and 20 %, whilst almost no transport was detected for lactucopicrin. Furthermore, costunolide and parthenolide reduced P-gp ABC transporter expression alongside an increase in caveolin-1, the main protein of caveolae. Remarkably, these two compounds improved barrier tightness by increasing the expression of both tight and adherens junctions. These findings open a new avenue to explore costunolide and parthenolide as promising compounds for brain therapies.