Pittosporum glabratum leaf (Shanzhi tea) essential oil: Chemical composition, anticancer activities and potential mechanisms in vitro and in vivo

Herein, the chemical constituents of Pittosporum glabratum leaf essential oil (EO) were analyzed, and its anticancer efficacy was explored in vitro and in vivo . Its primary phytochemicals were α -caryophyllene, ( E )- β -farnesene, and germacrene D. It displayed significant cytotoxicity against cancerous A549 cells and lower cytotoxicity against noncancerous MRC-5 cells. It induced cell cycle arrest in the G1 phase by downregulating CDK2-cyclin E1/2 and CDK4-cyclin D3 complexes and upregulating p21, thereby inhibiting A549 cell proliferation. It triggered A549 cell apoptosis via the mitochondrial pathway, resulting in the ratio increase of Bax/Bcl-2, ΔΨm decrease, Cyt c release, caspase-9 and caspase-3 activation, and PARP cleavage. It blocked migration ability by decreasing MMP-2, MMP-9, and N-cadherin levels. Additionally, it effectively suppressed tumor growth by inducing apoptosis of transplanted tumor cells in nude mice. Hence, P. glabratum leaf EO has remarkable anticancer properties and has great potential as an anticancer drug in the pharmaceutical field.