The fresh leaves of (Plectranthus amboinicus (Lour.) Spreng) were collected at Buon Ma Thuot city, Dak Lak province and essential oil, extracted by distillation, accounted for 0.18 - 0.3% by weight of the fresh leaves. Chemical compositions of Hung chanh essential oil have been examined by GC-MS. Thirty-four compounds were identified, among those the main compounds are: Carvacrol (52.32%), γ-Terpinene (18.92%), p-Cymene (7.56%), Caryophyllene (5.6%), cis-α-Bergamotene (2.86%), α-Humulene (2.68%) and Aromandendrene (1.78%). The essential oil was tested for the antibacterial activity on E. coli. The results showed that at the concentration of 8.5mg/mL, the essential oil inhibited by about 87.35% on E. coli. The antioxidant capacity of the essential oil was also determined by DPPH method. The highest antioxidant efficiency of the essential oil was 89.21% at concentration of 10µg/mL. The IC₅₀ value of the essential oil was 4.13μg/mL, eight-times less than that of ascobic acid (IC₅₀ value of 34.99μg/mL). The research shows that essential oil of the leaves of Plectranthus amboinicus (Lour.) Spreng might be a natural potential source of antibacterial and antioxidant agents.

Keywords: Plectranthus amboinicus (Lour.) Spreng, antibacterial, E. coli, essential oil, antioxidant