The present invention reported that SFE is suitable for Nigella sativa seeds oil extraction and fractionation. TQRF that were produced through SFE extractions (600 bars/40° C.) and fractionations (100-200 bars/40-60° C.) possessed high level of TQ and antioxidant activity. SFE fractionation efficiently concentrates the TQ content and antioxidant activity of Nigella sativa seeds oil in short time and low cost manners without using any hazardous organic solvents.