Objective: Evaluation of in vitro antioxidant activities of grape seed (Vitis vinifera) extract GSE, blackseed (Nigella sativa) extract NSE and curcumin CUR. Methods: In vitro antioxidative potential of GSE, NSE and CUR was evaluated through determination of total soluble phenolic content and reducing power. Also, the antioxidant activity was measured using linoleic acid peroxidation assay, phosphomolybdenum method, superoxide anion radical scavenging assay and DPPH free radical-scavenging assay. Results: GS and NS were extracted with 50% ethanol and methanol, respectively. Extraction yield of GSE and NSE was 127 and 109 mg/g dry weight, respectively. CUR elicited greater phenolic contents (115±0.04) than NSE (14±0.05) and GSE (5.2±0.06) mgGAE/g. Percentage scavenging activity of each sample against DPPH- was 1425%, 600% and 333% for CUR, NSE and GSE, respectively. Percentage superoxide scavenging activity was more pronounced in CUR (41%) than NSE (32%) and GSE (14%). CUR exhibited highest percentage antioxidant activity (87.1%) followed by NSE (77.6%) and GSE (61.4%) using phosphomolybdenum method. In Contrary, increased order of antioxidant activity using FTC-linoleic system was GSE > CUR > NSE. All the mentioned experiments were also conducted using vitamin E as a standard antioxidant. Strong linear regression between the total phenolic contents and above parameters in studied samples were noticed as indicated by high r2 at P<0.0001 that was slightly low in DPPH- scavenging activity than the other analyses. Conclusions: Our results indicated that, reducing power and antioxidative potentials of GSE, NSE and CUR may be attributed to high total phenolic contents. GSE, NSE and CUR may be valuable as food preservative and nutritional health supplements.
El-Beshbishy, H. A., Mohamadin, A. M., & Abdel-Naim, A. B. (2009). In vitro evaluation of the antioxidant activities of grape seed (Vitis vinifera) extract, blackseed (Nigella sativa) extract and curcumin. Journal of Taibah University Medical Sciences, 4(1), 23–35. https://doi.org/10.1016/S1658-3612(09)70078-2