Chemical Contents and Characterization of the Biologically Active Compounds of Nigella Sativa Linn. (Ranunculaceae) Seeds

ABSTRACT

The seed of Nigella sativa was evaluated for its chemical composition, medicinal as well as its nutritional values. The powdered seed was extracted with methanol to give the crude extract. Phytochemical screening of the crude extract revealed the presence of the following classes of natural products; alkaloids, tannins, flavonoids, saponins and anthraquinones, sterols and terpenes. The proximate analysis showed 12.00% moisture, ash content 3.00%, ether soluble extract 33.30% crude protein content 29.3%, total carbohydrate 7.2%, crude fibre content 5.33% and crude lipid 43.30%. The seed had a calorific value of 7203.44 kcal per 100g. The mineral elements determined were Calcium: - 2.052ppm, Magnesium: 0.313ppm, Potassium: 498.50ppm, Iron: 0.080ppm, Sodium: 494.40ppm. _ The amino acid composition showed some of the essential amino acids like Leucine 3.75±0.51, Isoleucine 2.09±0.96, Lysine 3.87±0.87, Methionine 1.57±0.26, and Arginine 3.05±0.03g/100. Proline, Tiytophan and Glycine were however not detected. These results indicate the high nutritional potential of Nigella sativa especially as a source of fat and protein. The oral N. Sativa L. seeds treatment decreased the diabetes-induced disturbances of hyper-cholesterolemia, hyperglycaemia and some haematological parameters of alloxan-induced diabetic rats. The anti-:-bacterial screening of both ·aqueous and methanol extract of Nigella sativa seeds using various concentrations of 0.1, 1.0, 10 and 1 OOmg/ml showed various zones of inhibition. These extracts showed pronounced anti-bacterial vii activity against Klebsiella pneumonia, Salmonella typhimurium and Escherichia coli, Pseudomonas aeruginosa and low activity against Staphylococcus aureus with zones of inhibition values of 22, 22, 23, 25 and 21 , respectively at 1 OOmg/ ml for the methanolic extract of Nigella Sativa seeds. This· revealed that the seeds of Nigella sativa possess remarkable antibacterial property and contain natural components of medicinal values. The GC-MS analysis of Nigella sativa seed fatty oil revealed the presence of three compounds, two of which were identified as 9,12-octadecadienoic acid, an unsaturated di-ester and an unidentified aliphatic ketone, respectively. These compounds may be responsible for the bioactivities of the seed and its use in ethnomedicine for the management of certain diseases.