Characterization of three Nigella Sativa L. Crude Oil Species, Measures of their Antioxidant Activity by DPPH

Abstract

In this study, physicochemical properties of Nigella Sativa L. seed oils original from Tunisia (NST) Libya (SNL) and Saudi Arabia (NSS) extracted in Soxhlet apparatus using hexane were investigated. The fatty acids and sterols in different oils were also identified by GC-MS. Antioxidants content and the measure of their antioxidant capacity was also performed. The following results were obtained for NST, NSL and NSS respectively: density d20 (0.83; 0.84 and 0.84) the refraction index (1.474; 1.471 and 1.477); the acidity index on mg KOH g-1 of oil (1.21; 1.22; and 1.36), the saponification index (74.61; 25.24 and 29.78) mg of KOH g-1. The extinction coefficients K232 and K270 were respectively (0.97; 0.59 and 0.74) and (0.31; 0.27 and 0.18). Total polyphenols contents are respectively: (200.57; 175.14 and 399.42 mg EAG kg-1); total carotenoids: (0.8; 0.74 and 0.5 mg kg-1DW). DPPH radical scavenging activity of seed oils evaluated in terms of their EC50 indicate a variation between 422.04 to 507.50 µg.mL-1. GC-MS analysis shows the presence of 12 fatty acids. ω 6 presents the highest percentage (53.55; 61.19 and 59.67) followed by ω 9 (24.39; 10 and 11.03) the palmitic acid were in the third position (12.74; 17.65 and 17.43), while the main saturated fatty acid was Stearic acid (3.80; 4.64; 5.13).