Different extracts of Liquidambar orientalisleaves were tested for their antimicrobial activity against eleven bacterial and one yeast strain by disc diffusion method. The antimicrobial activity was measured by disc diffusion and MIC. After that among extracts the best antimicrobial activity was detected.Volatile components of the ethanolic extracts of leaves of sweetgum analysed by GC/MS.
Ethanolic extracts of sweetgum leaves showed the best inhibition zones against Klebsiella pneumoniae (32mm). K.pneumoniae CCM 2318 showed the lowest sensitivity to 0.008 mg/mL concentration of ethanolic extracts. Ethanolic extracts of L. orientalis var. orientalis were showed the best antimicrobial activity MIC values of ethanolic extracts ranging from 0.008-64 mg.mL-1 to the tested bacteria. The GC/MS analyses allowed seven compounds to be determined; benzenepropanol (%49.30) and cinnamic acid (%35.89) were the main constituents of the of sweetgum leaves extract. All the extracts of L. orientalis leaves showed varying degrees of antimicrobial activity on the microorganisms tested. The antimicrobial activity was due to the presence the essential oils. Among the tested extracts the ethanolic extracts were the most active against the microorganisms tested compared to the reference antibiotics.