Stable Isotope Dilution Gas Chromatography–Mass Spectrometry for Quantification of Thymoquinone in Black Cumin Seed Oil

Abstract

Black cumin seed (Nigella sativa L.) is a widely used spice and herb, where thymoquinone (2-isopropyl-5-methyl-1,4-benzoquinone) is the major bioactive compound. Here, a stable isotope dilution (SID) gas chromatography-mass spectrometry (GC-MS) technique was developed for the quantification of thymoquinone. A doubly deuterated thymoquinone ([(2)H2]-thymoquinone) was synthesized for the first time with more than 93% deuteration degree shown by mass spectrometry and proton nuclear magnetic resonance ((1)H NMR). This compound was used as an internal standard for the quantification of thymoquinone using a SID GC-MS method. The validation experiment showed a recovery rate of 99.1 ± 1.1% relative standard deviation (RSD). Standard addition and external calibration methods have also been used to quantify thymoquinone, which cross-validated the developed stable isotope dilution assay (SIDA). In comparison to external calibration and standard addition methods, the SIDA method is robust and accurate. The concentration of thymoquinone in five marketed black cumin seed oils ranged between 3.34 and 10.8 mg/mL by use of SID GC-MS.

Structural Characterization, Antimicrobial Activity, and In Vitro Cytotoxicity Effect of Black Seed Oil

“…Generally, the seeds have been reported to contain many potentially important components in the matrices, but the major and most desired compounds in BSO are thymoquinone, dithymoquinone, thymohydroquinone, and thymol (Figures 3(a)–3(d)), owing to the conformational flexibility feature [29]. Earlier studies documented the existence of these components via chromatography-mass spectrometry analysis [30, 31]. In this study, the green-colored arrow in Figure 3 exhibits the desired bond that can undergo free rotation without a considerable energy cost, making the compounds very flexible.…”

“…Previously conducted research studies showed that thymoquinone is a major bioactive constituent of BSO. For this reason, different techniques have been used in the past to identify and quantify the thymoquinone compound in BSO, such as high-performance liquid chromatography (HPLC) [37], pulse polarography [38], differential pulse voltammetry [39], thin-layer chromatography [27], and gas chromatography-mass spectrometry (GC/MS) [30].…”

Thymoquinone, a bioactive component of Nigella sativa Linn seeds or traditional spice, attenuates acute hepatic failure and blocks apoptosis via the MAPK signaling pathway in mice

“…5 Furthermore, MAPK signaling cascades are activated by a variety of growth factors involved in kinds of biological responses, such as the production of cytokine and cell death. 8 Black cumin seed oil has been used as a traditional medicine of a range of diseases for a long history, such as diabetes, hypertension, inammation, gastrointestinal disturbances, and cancer. 7 Thymoquinone (TQ), a bioactive natural product obtained from the black cumin seeds of Nigella sativa Linn, is a widely used spice or herb throughout India and the Middle East.…”

Schwarzkümmel (Nigella sativa L.)

“…bei dessen Anteil im Öl je nach geografischer Herkunft der Pflanze stark schwankt [5,15,20,25,31]. Das Extraktionsverfahren beeinflusst den Gehalt an Thymochinon ebenfalls erheblich [25].…”