**8. Black cumin**

Seeds of *Nigella sativa* L., an annual flowering plant of Ranunculaceae family, have been of extensive use as a spice. Commonly known as black cumin, it is native to South and Southwest Asia and has diverse medicinal applications. Phytochemical analysis of black cumin seeds has showed presence of thymoquinone (TQ ), para-cymene, and carvone, linoleic acid, oleic acid, palmitic acid, and stearic acid (**Figure 7**) [132].

Black cumin has been reported to exhibit anti-inflammatory properties. Intra-peritoneal injection black cumin essential oil reduced inhibited carrageenaninduced paw oedema in rats thereby relieving inflammation [133]. Aqueous extracts of black cumin up-regulated the secretion of T-helper 2 cells and suppressed the secretion of pro-inflammatory cytokines viz. IL-6, TNFα, and NO [109]. Furthermore, black El-Mahmoudy et al., isolated TQ from essential oil of black cumin seeds and showed that TQ reduced nitrite accumulation and decreased inducible nitric oxide synthase levels (responsible for NO production) in rat peritoneal macrophages suggesting anti-inflammatory and cytoprotective effects of black cumin [134]. Methanol extract of seeds of black cumin (1 mg/ ml) protected erythrocytes against protein degradation and loss of deformability induced due to peroxide [135] and has proved to stimulate innate humoral immune responses [136]. Proteins purified from black cumin exhibit potent antioxidant activities [137]. Furthermore, neuroprotective effects of black cumin have also been reported [138].

In addition, black cumin exhibits anti-bacterial, anti-viral, anti-helminthic effects. Black cumin seed oil (BSO) showed protective effects against murine cytomegalovirus (MCMV) that targets liver and spleen. Treatment with BSO showed approximately 38% and 20% decrease in viral load in liver and spleen

*Spices-Reservoir of Health Benefits DOI: http://dx.doi.org/10.5772/intechopen.96471*

#### **Figure 7.**

*Chemical constituents of Black Cumin.*

respectively in MCMV infected mice [139]. Decrease in the number of *S. mansoni* worms in liver and eggs in both liver and intestine of mice has been observed after treatment with black cumin oil at a dose of 2.5 ml/kg and 5 ml/kg [140]. TQ has proved to be an effective bactericidal agent as it inhibited growth of *Staphylococcus aureus* (BIC50 = 22 μg/ml) [141], *Salmonella typhii* [142] *Streptococcus mutans* [143]. Further, black cumin inhibited the *P. yoelii* parasitemia by 94% [144].

Black cumin has protective effects against diabetes. Black cumin seeds (BCS) led to the decrease in elevated levels of glucose with increase in GSH levels and further inhibited liver damage induced by lipid peroxidation in diabetic rabbits [145]. In addition, improvement of glucose homeostasis in patients with type 2 diabetes on administration of black cumin (2 g/day for 3 months) with hypoglycemic drugs have also been reported [146].

Furthermore, aqueous extracts of black cumin significantly up-regulated cytotoxic activity of natural killer cells against YAC-1 tumor cells [109]. Oral administration of TQ at a dose of 0.01% suppressed benzo(a)pyrene induced forestomach tumor in mice by 70% [147] exhibiting anti-tumor effects.

Minor toxicological effects have also been reported, however, numerous studies demonstrated diverse therapeutic effects of black cumin and TQ and have supported its safe consumption [132].

#### **9. Conclusion**

Spices are rich source of bioactive components with innumerable beneficial attributes that have been verified and accepted by modern world in the past few decades. These are nowadays considered as a crucial & natural component of our daily diet. Consumption of spices aids in combating diseases when they are at their peak, for instance, best remedy for stomach infections are fennel seeds; turmeric is the tonic for fever-related diseases. Antimicrobial activities of spices make them valuable in hot climates as they prevent food spoilage. Although they lower the risk of various diseases such as diabetes, cancer, etc., there are some contradictions about their use. Despite all the pleiotropic effects offered by the spices, further evaluation about their mechanism of action is mandated to validate their clinical effects and their amount of consumption.
