Patchouli alcohol, an essential oil of Pogostemon cablin, exhibits anti-tumorigenic activity in human colorectal cancer cells

Patchouli alcohol (PA) is one of the important compounds isolated from the essential oil of Pogostemon cablin (patchouli). PA has neuroprotective, anti-influenza and anti-inflammatory activities. However, anti-cancer activity of PA has not been studied so far. We performed in vitro study to investigate whether PA affects proliferation and apoptosis of human colorectal cancer cells, and to define potential molecular mechanisms. PA suppressed cell growth and induced apoptosis in a dose-dependent manner in human colorectal cancer cells (HCT116, SW480). In addition, PA decreased cell growth in MCF7, BxPC3, PC3, and HUVEC cells. Exposure of PA to HCT116 and SW480 cells activated p21 expression and suppressed the expressions of cyclin D1 and cyclin-dependent kinase 4 (CDK4) in a dose-dependent manner. In addition, PA attenuated the expressions of HDAC2 (histone deacetylase 2) and c-myc, and HDAC enzyme activity. We also observed that PA induced the transcriptional activity of NF-κB through an increase of nuclear translocation of p65. These findings suggest that PA exerts an anti-cancer activity by decreasing cell growth and increasing apoptosis in human colorectal cancer cells. The proposed mechanisms include the inhibition of HDAC2 expression and HDAC enzyme activity, and subsequent downregulation of c-myc and activation of NF-κB pathway.