Terpenoid components, antioxidant and antibacterial activities of essential oils from fresh immature and mature leaves of Blumea balsamifera, extracted with different hydrodistillation periods

Volatiles and antioxidant capacities in essential oils (EOs) from fresh immature and mature leaves of Blumea balsamifera, extracted with different extraction periods of hydrodistillation, were investigated. There were seven major terpenoid compounds in the leaf extracts, including 2 monoterpenes of camphor and L-borneol, and 5 sesquiterpenes of silphiperfol-5-ene, 7-epi-silphiperfol-5-ene, {beta}-caryophyllene, {ramshorn}-eudesmol, and -eudesmol. Different hydrodistillation periods resulted in different quantitates and compositions of the terpenoids in EOs. The yield of EOs from the immature leaves was 1.4 times higher than the mature ones, whereas 73% of the yield was collected from the first 6 h of hydrodistillation. Camphor and L-borneol were almost collected in the first 6 h, while {beta}-caryophyllene, silphiperfolene, and 7-epi-silphiperfolene were above 80%, but {ramshorn}-eudesmol and -eudesmol were only 32 and 54% released. {beta}-Caryophyllene, {ramshorn}-eudesmol, and -eudesmol were found higher in the mature leaf EOs. Antioxidant capacities in EOs were positively related to terpenoid contents. Antibacterial activity of EOs from the immature leaves was subsequently tested. Although EOs from the hydrodistillation period of 12-18 h contained fewer terpenoid compositions, it showed the same minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) on Escherichia coli and Pseudomonas aeruginosa, compared to 0-6 h EOs.