The compounds in Ginger (Zingiber officinale-Roscoe) essential oil provenience China and wild oregano (Origanum vulgare) essential oil of Romanian origin were identified by GC/MS and their antioxidant and antifungal properties were evaluated. Wild oregano oil was characterized by high content of oxygenated monoterpenes hydrocarbons (84.05%) of which carvacrol was the most abundant (73.85%) followed by b-linalool (3.46%) and thymol (2.29%). Ginger oil had a higher content of sesquiterpene hydrocarbons including zingiberene (31.47%), b-sesquiphellandrene (13.76%), a-curcumene (10.41%), a-farnesene (8.31%) and b-bisabolene (7.55%) but a lower content of oxygenated monoterpenes (7.97%). The high content of oxygenated monoterpens of wild oregano oil is in accordance with total content of polyphenols determined by the Folin�Ciocalteu method (6.71�0.73 mg of gallic acid equivalent per g oil). Ginger oil had only 1.34�0.22 mg gallic acid equivalent per g oil. Wild oregano oils exhibited appreciable in vitro antioxidant activity as assessed by 2, 2`-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and 2,2�-azino-bis (3 ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS). The sample concentration required to scavenge 50% of the DPPH free radicals was 0.76�0.13 mg/mL for wild oregano oil compared to 20.22�2.12 mg/mL for ginger oil. Also, wild oregano oils showed significant inhibitory activity against selected pathogenic fungi (Fusarium oxysporum, Aspergillus flavus and Penicillium expansum). 1�L of oregano oil is sufficient for almost 75% growth inhibition of Aspergillus flavus compared to ginger oil which shows antifungal activity at 240�L for 78% growth inhibition. It can be concluded that wild oregano oil could be used as food preservative in some food products in which Fusarium oxysporum, Aspergillus flavus and Penicillium expansum could grow and have potential to produce health hazards mycotoxines.
Aspergillus flavus grown in peptone as the carbon source exhibits spore density- and peptone concentration-dependent aflatoxin biosynthesis