Determination of oxygen radical absorbance capacity of black cumin (Nigella sativa) seed quinone compounds.

Tesařová H., Svobodová B., Kokoška L., Maršík P., Přibylová M., Landa P., Vadlejch J.

Keywords: Antioxidative activity, Dihydrothymoquinone, Thymoquinone, DPPH, ORAC
Abstract: In this study, the antioxidant capacities of main quinone constituents of Nigella sativa seeds, namely dithymoquinone (1), thymohydroquinone (2) and thymoquinone (3), were compared using DPPH and ORAC methods. The best scavenging activity was produced by 2, which showed a remarkable activity of 2.60 Trolox equivalents (TE) in a concentration range between 1.6 and 6.4 μg/mL and IC50 value of 2.4 μg/mL in ORAC and DPPH assays, respectively. Contrastingly, 3 possessed only weak DPPH scavenging efficacy (IC50 = 170 μg/mL) but significant antioxidative action of 1.91 TE in ORAC assay. No effect has been observed for 1. Additionally, modified protocol for synthesis of 2 has been developed with aim to enhance its availability for further studies as well as for its future potential use. Based on the results of this study, we conclude that 2 could be considered as a compound with prospective antioxidative properties.
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IEB authors: Přemysl Landa, Petr Maršík, Marie Kvasnicová