Eryngium foetidum L. Essential Oils: Chemical Composition and Antioxidant Capacity.

Background:Eryngium foetidum essential oils from Nigeria were investigated for the first time in order to ascertain their potency as natural antioxidants. E. foetidum is an aromatic and medicinal herb used in ethno-medicine and as a traditional spice for foods. Methods: The hydro-distilled oils of E. foetidum were subjected to gas chromatography-mass spectrometry (GC-MS) analysis. Free radical scavenging capacity of the volatile oils was determined using 2, 2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) assays. Results: Leaf volatile oil contained a high proportion of (E)-2-Dodecenal (28.43%), 13-tetradecenal (27.45%), dodecanal (14.59%) and 2,4,5-trimethylbenzaldehyde (10.77%); the stem oil comprised of dodecanal (20.21%), 2,4,5-trimethylbenzaldehyde (18.43%) and (E)-2-dodecenal (8.27%), while 2,4,5-trimethylbenzaldehyde (56.08%), 13-tetradecenal (9.26%) and (E)-2-dodecenal (7.65%) were the most dominant in the root oil. The IC50 values for the leaf, stem and root oils were 56 µg/mL, 46µg/mL and 54.5 µg/mL respectively in the DPPH assay while the leaf oil exhibited the highest reducing potential among the test oils in the FRAP assay. Conclusions: The Nigerian E. foetidum volatile oils contain high amount of acyclic aldehydes and aromatic compounds. The oils are a potential source of natural antioxidant as demonstrated by their strong antioxidant activity.