Study of the Phytochemical Composition of Nigella sativa Herbs

Abstract

Nigella sativa L. is an established spicy oil plant, largely known for seed oil (black cumin oil). The aerial parts of this plant remains less studied, despite the prevailing mass of the vegetative part of the plant. The aim of this research was to study the phytochemical composition of Nigella sativa herbs and develop a method for quantitative determination of the content of the total flavonoids in Nigella sativa L. herbs by UV/VIS spectrophotometry. Nigella sativa L. herbs collected in early August 2020-2022 in the Botanical Garden of Samara University. Water-alcohol extracts were obtained from the herb of Nigella sativa, which were used for the preparative isolation of individual compounds, as well as for quantitative analysis (spectrophotometry). Five dominant compounds of flavonoid and sterol nature have been identified as nicotiflorin (kaempferol 3-O-rutinoside), rutin (quercetin 3-O-rutinoside), nigelflavonoside G (3-O-β-D-[α-L-O-rhamnopyranosyl-(1→6)]-glucopyranoside-[(2→1)-O-β-D-glucopyranosyl-(2→1)-O-β-D-glucopyranosyl]-3,5,6,7,4'-pentahydroxy-3'-methoxyflavone), -sitosterol, and daucosterol (β-sitosterol 3-O--D-glucopyranoside), which were first described for Nigella sativa L. There was developed the method of determination of the total flavonoids calculated on rutin in the herb of Nigella sativa L. by spectrophotometry. The content of the total flavonoids in the herb Nigella sativa L. is varied from 1.17±0.16% to 1.72±0.22% over a three-year period. The error of single determination of flavonoids in the Nigella sativa L. herbs with confidence probability of 95% is ±4.17%. The results of the studies carried out indicate the expediency of standardization of Nigella sativa L. herbs by determining the content of the main group of substances in raw materials – flavonoids calculated on rutin by spectrophotometry at a wavelength of 410 nm.