Chemical profile and antibacterial activity of essential oil from ironwood (Eusideroxylon zwageri) sawdust

The current study describes for the first time the chemical compositions and antimicrobial activity of essential oils from ironwood sawdust (Eusideroxylon zwageri) obtained from Borneo Island. Fifteen terpene metabolites were identified by GC-MS of the ironwood sawdust essential oil extracted by steam distillation. (E)-beta-Caryophyllene was the oil's major compound (35.81 +/- 0.25%), while its oxygenated derivative (caryophyllene oxide, 8.78 +/- 0.08%) was the third biggest terpene. alpha-Copaene (13.05 +/- 0.02%) was also observed in a significant amount together with other minor sesquiterpene hydrocarbons and oxygenated sesquiterpenes. The oil also exhibited antibacterial activities against Gram-positive Multi-Drug Resistant Staphylococcus aureus (MRSA) and Gram-negative Escherichia coli (strain ESBL) during a disc diffusion assay with inhibition zones of 6.13 +/- 0.03 mm and 3.35 +/- 0.05 mm, respectively.