Guaiazulene
Guaiazulene is a bicyclic sesquiterpene that can cross the blood-brain barrier. Guaiazulene exhibits various biological activities such as anti-inflammatory, antioxidant, hepatoprotective, antibacterial, and anti-tumor properties. Guaiazulene is also commonly used as a colorant in cosmetics. Guaiazulene shows in vitro cytotoxicity to rat neuronal cells and N2a neuroblastoma cells at high concentrations[1][2][3][4].