The Anticancer, Antioxidant and Antimicrobial Properties of the Sesquiterpene β-Caryophyllene from the Essential Oil of Aquilaria crassna

The present study reports a bioassay-guided isolation of beta-caryophyllene from the essential oil of Aquilaria crassna. The structure of beta-caryophyllene was confirmed using FT-IR, NMR and MS. The antimicrobial effect of beta-caryophyllene was examined using human pathogenic bacterial and fungal strains. Its anti-oxidant properties were evaluated by DPPH and FRAP scavenging assays. The cytotoxicity of beta-caryophyllene was tested against seven human cancer cell lines. The corresponding selectivity index was determined by testing its cytotoxicity on normal cells. The effects of beta-caryophyllene were studied on a series of in vitro antitumor-promoting assays using colon cancer cells. Results showed that beta-caryophyllene demonstrated selective antibacterial activity against S. aureus (MIC 3 +/- 1.0 mu M) and more pronounced anti-fungal activity than kanamycin. beta-Caryophyllene also displayed strong antioxidant effects. Additionally, beta-caryophyllene exhibited selective anti-proliferative effects against colorectal cancer cells (IC50 19 mu M). The results also showed that beta-caryophyllene induces apoptosis via nuclear condensation and fragmentation pathways including disruption of mitochondrial membrane potential. Further, beta-caryophyllene demonstrated potent inhibition against clonogenicity, migration, invasion and spheroid formation in colon cancer cells. These results prompt us to state that beta-caryophyllene is the active principle responsible for the selective anticancer and antimicrobial activities of A. crassnia. beta-Caryophyllene has great potential to be further developed as a promising chemotherapeutic agent against colorectal malignancies.