Abstract
Essential oils from the leaves, aerial stems, basal stems, and rhizomes of Etlingera fimbriobracteata (K.Schum.) R.M.Sm. were analyzed using a gas chromatography-flame ionization detector (GC-FID) and by gas chromatography-mass spectrometry (GC-MS). beta-Pinene (67.8%) and 1,8-cineole (37.2%) were the main components of the oils from leaves and aerial stems, respectively, whereas decanal was the main component of basal stems and rhizomes (27.5% and 34.4%, respectively). The antioxidant activities of the oils were evaluated using several in vitro assays; the 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) free radical scavenging assays, the reducing power ability (RPA) assay, and the ferric reducing antioxidant power (FRAP) assay. In all the tests, essential oils from different plant parts showed very poor antioxidant activity compared with those of the reference standards, ascorbic acid (AA) and butylated hydroxytoluene (BHT). However, all the oils exhibited moderate to potent broad-spectrum antimicrobial activity against all tested strains except for Pseudomonas aeruginosa. In disc diffusion and broth microdilution assays, the inhibition zones and MIC values of the essential oils were in the range of 8-87.7mm and 2.4-625 mu g/mL, respectively. Because of their strong antimicrobial activity, the essential oils of E. fimbriobracteata could be a potential alternative to conventional antimicrobials in food, cosmetics, and pharmaceutical industries. (C) 2016 Elsevier B.V. All rights reserved.