Mechanism of Action
Thymoquinone, one of the chief constituents of Nigella sativa oil has antioxidant effects and restored the levels of lactate dehydrogenase, gluthathione, and SOD in animal models (6) (7) (9). This may explain Nigella sativa’s hepatoprotective effects (3) (4). Studies have also shown that Nigella sativa oil has anti-inflammatory property by inhibiting cyclooxygenase and lipoxygenase (18). An in vitro study demonstrated that nigellone, a constituent of the crude extract of Nigella sativa seeds, inhibited histamine release from rat peritoneal mast cells (10) and may reduce allergy symptoms in humans (12). Nigella sativa decreased hypertension in rats possibly due to its diuretic effects (5). It was also shown to decrease uterine smooth muscle contractions (14). The antioxidant effect is thought to protect tissues from radiation injury (15). However, it is not clear if this would also make radiation therapy less effective. Thymoquinone administered to mice reduced the incidence of stomach tumors (7). Possible mechanisms include inhibition of DNA synthesis (7), and promotion of apoptosis by inhibiting cell growth in G1 phase (8).
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2. Haq A, Abdulatif M, Lobo PI, et al. Nigella sativa: effect on human lymphocytes and polymorphonuclear leukocyte phagocytic activity. Immunopharmacology 1995;30(2):147-55.
3. Ali BH and Blunden G. Pharmacological and toxicological properties of Nigella sativa. Phytother Res 2003;17(4):299-305.
4. Dada MH and Abdel-Rahman MS. Hepatoprotective activity of thymoquinone in isolated rat hepatocytes.Toxicol Lett 1998. 95(1): p. 23-9.
5. el Tahir KE, Ashour MM, al-Harbi MM. The cardiovascular actions of the volatile oil of the black seed (Nigella sativa) in rats: elucidation of the mechanism of action.Gen Pharmacol 1993;24(5):1123-31.
6. El-Abhar HS, Abdallah DM, Saleh S. Gastroprotective activity of Nigella sativa oil and its constituent, thymoquinone, against gastric mucosal injury induced by ischaemia/reperfusion in rats. J Ethnopharmacol 2003;84(2-3):251-8.
7. Badary OA, et al. Inhibition of benzo(a)pyrene-induced forestomach carcinogenesis in mice by thymoquinone. Eur J Cancer Prev 1999;8(5):435-40.
8. Gali-Muhtasib H, Diab-Assaf M, Boltze C, et al. Thymoquinone extracted from black seed triggers apoptotic cell death in human colorectal cancer cells via a p53-dependent mechanism. Int J Oncol 2004;25(4): 857-66.
9. Ait Mbarek L, et al. Anti-tumor properties of blackseed (Nigella sativa L.) extracts. Braz J Med Biol Res 2007;40(6):839-47.
10. Chakravarty N. Inhibition of histamine release from mast cells by nigellone. Ann Allergy 1993;70(3):237-42.
12. Kalus U, Pruss A, Bystron J, et al. Effect of Nigella sativa (black seed) on subjective feeling in patients with allergic diseases. Phytother Res 2003;17(10):1209-14.
14. Iddamaldeniya SS, Thabrew MI, Wickramasinghe SM, et al. A long-term investigation of the anti-hepatocarcinogenic potential of an indigenous medicine comprised of Nigella sativa, Hemidesmus indicus and Smilax glabra. J Carcinog 2006;11.
15. Cemek M, Enginar H, Karaca T, Unak P. In vivo radioprotective effects of Nigella sativa L oil and reduced glutathione against irradiation-induced oxidative injury and number of peripheral blood lymphocytes in rats.Photochem Photobiol 2006;82(6):1691-6.
18. Houghton PJ, Zarka R, de las Heras B, Hoult JR. Fixed oil of Nigella sativa and derived thymoquinone inhibit eicosanoid generation in leukocytes and membrane lipid peroxidation. Planta Med 1995;61(1):33-6.
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