Eucalyptus essential oil is an important aroma-therapeutic agent in the treatment of diverse diseases and ailments in human and animals. The aim of this study was to determine the composition and pharmacological properties of the seed essential oil of E. citriodora from Nigeria. The essential oil was extracted by hydro-distillation using Clevenger-type apparatus and analyzed using GC-MS. The total phenolic content, antioxidant, anti-inflammatory, analgesic and antimicrobial activities were measured by Folin-Ciocalteu’s, 2,2ʹ-diphenyl-1-picrylhydrazyl, reduction antioxidant, carrageenan, formalin and agar-well diffusion assays respectively. The GC-MS result showed the presence of 22 organic compounds making up 98.8% of the percentage composition of the essential oil. The main components of the oil were palmitic acid (29.00%), oleic acid (10.00%), E,E,E-α-springene (9.00%), 2-ethenyl-2,5-dimethyl-4-hexen-1-ol (8.00%), 2,4-dimethylheptane (6.00%), hexahydrofarnesyl acetone (5.00%), geranyl butanoate (4.00%), farnesol (4.00%), geranylgeraniol (4.00%) and trans-2-methyl-2-(4-methyl-3-pentenyl)-cyclopropanecarboxaldehyde (4.0%). The TPC value was 175.84±0.00 µgmg-1 GAE. The DPPH IC50 and AAI values of the essential oil were 3.00 µgml-1 and 13.30, respectively. The essential oil was capable of scavenging free radicals in a range of 67.77-71.95%, while the FRAP EC50 value was 2.00 µgml-1. The essential oil exhibited high anti-inflammatory effect with value of 43.80% and analgesic potential by inhibition of both neurogenic (41.32%) and inflammatory pains (11.11%). The zones of inhibition were between 0.80-18.00 mm. The seed essential oil of E. citriodora consists of useful phyto-therapeutic compounds that may be of great use in the food and pharmaceutical industries.

Keywords: Eucalyptus citriodora, seed essential oil, GC-MS, phytochemicals, pharmacological activity.