Antioxidant Activity of Essential Oil from Black Zira (Bunium persicum Boiss.) Obtained by Microwave-assisted Hydrodistillation

Microwave-assisted hydrodistillation (MAHD) at three levels of microwave power (180, 360, and 540 W) and the traditional hydrodistillation (HD) were applied to obtain essential oils from Bunium persicum Boiss. (Black Zira). MAHD at 540 W started much earlier than that of HD (4 min vs. 38 min, respectively). By the time the extraction of essential oils started with HD, almost 50% of the total essential oils (2.15%, w/w yield) had been extracted with MAHD at 540 W. Analysis of the essential oils using gas chromatography-mass spectrometry showed that γ-terpinene (28.16-31.13%, w/w), cuminaldehyde (24.85-29.20%), ρ-cymene (14.67-16.50%) and limonene (6.13-8.28%) were their main constituents, with a similar composition both after HD and MAHD extraction. The antioxidant activity (reported as IC50) of essential oil extracted by HD was 9.31 mg ml-1 and those of MAHD at 180, 360, and 540 W were 8.62, 8.79, and 6.45 mg ml-1, respectively. Microwave irradiation did not cause any adverse effect on the antioxidant activities of the extracted essential oils, therefore, it can be used as a good alternative method to obtain essential oils from B. persicum.