Proximate composition, phytochemical screening and in vitro antioxidant determination of seed extract of Nigella sativa (black cumin)

Abstract

Nigella sativa, is a traditional herb valued for its therapeutic potentials and rich bioactive makeup. The pulverised Nigella sativa was screened for proximate composition, while the ethanol extract of Nigella sativa was examined for phytochemical components and in vitro antioxidant activity using a 2,2 diphenyl-2-picryl hydroxyl (DPPH) quenching assay, ferric reducing antioxidant potential (FRAP)
Assay and total antioxidant capacity (TAC) using standard established protocols. The proximate composition revealed that Nigella sativa had a high carbohydrate, moisture and crude fibre content but a low crude fat, crude protein and ash content. The study showed that saponin, alkaloids, terpenoids, cardiac glycosides and steroids were presemt. However, flavonoids, phenols, coumarins, tannins,
anthraquinone and phlobatannins were seen to be absent. The ethanol extract exhibited high DPPH radical scavenging activity, with IC50 value of 477.98 μg/mL. An elevated level of FRAP was observed as the concentration of the sample increased, while total antioxidant capacity was significantly lower than the standard. The in vitro antioxidant activity of N. sativa was constrasted with ascorbic acid. Results obtained from this study indicated that N. sativa seeds may may have significant therapeutic potential when used to treat and manage metabolic disorders.