CHEMICAL COMPOSITION AND ANTIOXIDANT PROPERTIES OF THE ESSENTIAL OIL OF NIGELLA SATIVA L.

The chemical composition of the essential oil obtained from N. sativa was analyzed by GC/MS and the components identified were: p-cymene (22.05%) followed by alpha-thujene (6%), alpha-pinene (1.11%), camphene (11%), sabinene (1%), beta-pinene (7%), beta-myrcene (0.21%), alpha-phellandrene (0.45%), limonene (0.13), gamma-terpinene (5.12%), terpinolene (0.23%), camphor (1%), carvone (0.32%), thymoquinone (20.32%), thymol (10.12%), carvacrol (10%), longicyclene (0.9%) and borneol (0.43). The oils were also subjected to screening for their possible antioxidant activity by using 2,2-diphenyl-1-picrylhydrazyl (DPPH) assays. Thymol (13.0 +/- 0.8 mu g/ml), thymoquinone (12.6 +/- 0.0 mu g/ml) and carvacrol (12.03 +/- 0.0 mu g/ml) showed appreciable antioxidant activity in DPPH test. Antioxidant activity guided fractionation of the oil was carried out by the TLC-bioautography screening and fractionation resulted in the separation of the main antioxidant compound which were identified as thymoquinone (51%), thymol (25%) and carvacrol (8%).