Abstract
Black seeds (Nigella sativa) owe an important place due to its more demand as a food as well as medicine. A lack of information does exist regarding the quality and safety for market-available food-grade samples of black seed (BS). The aim of this study is to investigate the quality and standardize the BS samples according to world health organization (WHO) guidelines of instrumental analysis and pharmacological activities. Instrumental analysis was performed with the help of ASE (accelerated solvent extraction), IR (infrared spectroscopy), UHPLC (ultra-high-performance liquid chromatography) and NMR (nuclear magnetic resonance spectroscopy) whereas ash values and chemical tests were applied for physicochemical analysis. DPPH (2,2-diphenyl-1-picrylhydrazyl), ABTS (2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) and cytotoxicity assay were performed as well. A high extract yield (g) with recovery of 4.4 ± 7.7 (22%) for Pakistani, 3.3 ± 4.7 (16.5%) for Indian and 3.02 ± 10.2 (15.1%) for Saudi Arabian sample. Chemical tests showed the presence of phenolic compounds and flavonoids. Saudi Arabian samples showed less amount for ash values (total-, water soluble- and acid insoluble ash). The samples were standardized further with the help of NMR and IR. A significant amount of micro- and macronutrients was observed in Saudi Arabian sample. With regard to the major active substance Thymoquinone (THQ; ng/mL), the order of concentration was observed as; Saudi Arabian sample (33141.1) > Pakistani (7677.2) > Indian sample (3998.6). A more potency for Saudi Arabian sample was observed during antioxidant and cytotoxicity assays. The method was successful to effectively discriminate the samples from different geographical origin, in terms of quality.
Highlights
Nigella sativa (N. sativa), family; Ranunculaceae, or black seed (BS), is a globally used medicinal plant which is an intact part of various systems including “The medicine of Prophet Mohammad P.B.U.H”, “Indian traditional medicine” and “Unani Tibb”
The desire to reduce such disadvantages has led to the development of newer techniques for extraction of analyte including; pressurized liquid extraction (PLE), microwave assisted extraction (MAE), supercritical fluid extraction (SFE) and accelerated solvent extraction (ASE)
UHPLC is effective compared to other methods, as it utilizes smaller column with less particles size which increases the number of efficiency plates for less retention time and flow rate (Aboul-Enein and Abou-Basha, 1995; Ahmad et al, 2018)
Summary
Nigella sativa (N. sativa), family; Ranunculaceae, or black seed (BS), is a globally used medicinal plant which is an intact part of various systems including “The medicine of Prophet Mohammad P.B.U.H”, “Indian traditional medicine” and “Unani Tibb”. It grows in the Middle East, Eastern Europe, and Western Asia where they are used in food as a flavoring additive in breads and pickles (Tavakkoli et al, 2017; Srinivasan, 2018). The quality for black seed samples will be evaluated and standardized as per WHO (World health organization, 2011) procedures including; instrumental analysis (IR, ASE, UHPLC, NMR) for extraction and quantitation, biological evaluation (in vitro or in vivo pharmacological activities). Biological activities will be tested for further confirmation of the quality
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