Chemical composition, antioxidant and antibacterial activities of essential oil from Korean Citrus unshiu peel

The chemical composition, antioxidant and antibacterial activities of essential oil from peel of Citrus unshiu which cultivated in South Korea were investigated. Eight compounds were identified as l-limonene (88.11%), γ-terpinene (4.66%), cyclohexane, 2,4-diisopropenyl-1-methyl-1-vinyl (1.82%), diethyl phthalate (1.02%), β-linalool (0.97%), β-myrcene (0.91%), α-farnesene (0.91%) and o-cymene (0.85%) by GC-MS. The SC50 values of this essential oil on DPPH and superoxide anion were 0.21 and 0.22% (v/v), respectively. The results of zone of inhibition, MIC, MBC and cell viability demonstrated the essential oil ofCitrus unshiu peel displayed antibacterial effect against B. cereus KCTC 14042, B. subtilis ATCC 6633 and S. aureus ATCC 6538. The release of cell material and potassium ion from the B. subtilis ATCC 6633 cells treated with essential oil was further investigated. SEM observation also revealed the damaging effect of the essential oil on the morphology of B. subtilis ATCC 6633 cells at minimum inhibitory concentration.