To develop a new natural antibiotics from Koran plant resources for dealing with the current situation regarding the rapid increase in antibiotic-resistant pathogen, the in vitro inhibitory activities of essential oils from the young leaves of Glehnia littoralis (Umbelliferae) as well as its main constituents were evaluated against susceptible and resistant species of Streptococcus pneumoniae. The essential oil fraction of G. littoralis and its main components, $alpha-and;eta-pinene$, exhibited significant inhibitory activities against the antibiotic-susceptible and resistant strains of S. pneumoniae, with MICs (minimum inhibiting concentrations) ranging from 4.0mg/ml to 16mg/ml. No remarkable differences were shown between the susceptible and resistant strains. Moreover, the disk diffusion test disclosed that these inhibitory activities were dosedependent. Furthermore, data from the checkerboard titer test with FICIs (fractional inhibiting concentration indices) from 0.15 to 0.28 indicated synergisms between norfloxacin and $alpha-or;{eta}-pinene$ in activity against S. pneumoniae KCCM49629 and S. pneumoniae CCARM4059.
