Antioxidant activity of Algerian Nigella sativa total oil and its unsaponifiable fraction

Abstract

Background/Aim: Nigella sativa(NS) oil is usually considered as oxidatively stable, the aim of this study is to evaluate its antioxidant capacity in vitro and that of its unsaponifiable fraction by several mechanisms. Methods: NS seed total oil (TO) was extracted with n-hexane and this oil was further the matrix to extract the unsaponifiable fraction (UF). TO and its UF were investigated for the antioxidant activity using the following spectrophotometric assays:ABTS (2,2’-azino-bis 3-ethylbenzthiazoline-6-sulfonic acid), DPPH (2, 2’- diphenyl-1-picrylhydrazyl)and H2O2 (Hydrogen peroxide) radicals scavenging tests and lipid peroxidation inhibition capacity assay. All tests were realized by spectrophotometric methods. Results: Quantitative determination of phenols and flavonoids in TO and UF showed that UF has the highest phenolic and flavonoid concentrations with 24,73±0,51 µg GAE/g extract and 8,31±0,40 µg QAE/g extract respectively. All antioxidant assays showed that UF has the strongest antioxidant capacity with; IC50 0,455 ±0,01 mg/ml in ABTS scavenging assay, IC50 113,24 ±0,425 mg/ml in DPPH scavenging assay and IC50 of 0,324±0,003 mg/ml in H2O2 scavenging assay, equally, UF has the strongest Lipid peroxidation inhibition capacity With a percentage inhibition of 57.5%. Conclusion: The results obtained in this investigation showed that the UF has an important antioxidant capacity, which make NS an attractive source of new therapeutic components.