Nigella sativa L. (Black Cumin): A Promising Natural Remedy for Wide Range of Illnesses

Table 1

The effects of N. sativa and its active component, thymoquinone (TQ) on neurological and mental disorders.

Neurological or mental Disorders	Model used and intervention (s)	Finding (mechanism)	References
Alzheimer’s disease (AD)	Lipopolysaccharide-induced AD in mice, received TQ (2.5 & 5mg/kg) for 7 days.	(i) ↓ TBARS & 5-LOX levels; (ii) ↑ GSH extent and SOD action; (iii) Causes disaggregation of Aβ peptide; (iv) prevents declining of neurons; (v) Slows degeneration of cognitive ability	[64, 65]
	Aβ-induced neurotoxicity (analyzed by culturing hippocampus and cortical neurons).; TQ is administered along with A for 72 hours	(i) Reducing Aβ-induced neurotoxicity. (Improved cell viability) by: (ii) Inhibiting mitochondrial membrane potential depolarization; (iii) Hindering reactive oxygen species generation	[66]
Parkinson’s disease (PD)	1-methyl-4-phenylpyridinium (MPP^+) and rotenone-induced neurotoxicity in PD model, cultures were treated with TQ (0.01, 0.1, 1 and, 10 μM) on day 8th for 4 days.	(i) Rescued dopaminergic neurons through: (ii) Its antioxidant and anti-inflammatory effects	[67]
	Experimental model of early PD induced by 6-hydroxydopamine neurotoxicity, pretreatment of daily TQ (5 & 10 mg/kg) and one additional dose after surgery were used.	(i) ↓ MDA level; (ii) Prevents loss of neurons in substantia nigra; (iii) Protects hippocampal & human induced pluripotent stem cell against α-synuclein induced synaptic toxicity	[68, 69]
Depression and anxiety	(i) Open field and elevated plus maze models; forced swim test; (ii) Locomotor behavior in familiar and new environment in rats, N. sativa oil (0.1 mL/day) aqueous seed extract (2 mL/day) orally for 4-6 weeks	(i) ↑ in open field activity & struggling time; (ii) ↑ 5-HT; (iii) ↓ 5HIAA level in the brain; (iv) ↑ tryptophan level in plasma & brain; (v) ↑ locomotors activity in novel environment; (vi) ↑ brain DA level	[59, 70, 71]
	Stressed and unstressed mice, 10 and 20 mg/kg of TQ for 4 weeks	Unstressed mice: at 10 & 20 mg/Kg showed anti-anxiety; (i) without altering nitrite levels; (ii) ↑ GABA content (only 20mg/Kg).; Stressed mice: 20 mg/kg showed anxiolytic effects with; (i) ↓ plasma nitrite level; (ii) Reversal of reduced GABA	[72]
	Randomized control trial on healthy human subjects, N. sativa capsule (500 mg) daily for 4 weeks.	(i) Stabilize disturbed mood; (ii) ↓ anxiety; (iii) Modulate memory positively	[73]
Epilepsy	Pentylenetetrazole-induced seizure, N. sativa oil; TQ	(i) Prevented seizure occurrence; (ii) ↓ Reactive oxygen species generation; (iii) Reduced seizure score; (iv) Showed additive effects with phenobarbitone	[74–76]
	Double-blinded placebo randomized control trial (refractory epilepsy), TQ as adjunctive therapy for 4 weeks	(i) Significant reduction of seizure frequency (those who received combination therapy)	[77]
Opioid dependence and Tolerance	Morphine brought tolerance and dependency in mice, 4mL/kg of N. sativa oil along with morphine (5mg/kg)	(i) Attenuated the development of tolerance; (ii) Inhibited nitric oxide overproduction; (iii) ↓ in brain MDA level	[78]
	Randomized trial (on 35 known addicts of opiates), 500 mg N. Sativa three times daily	(i) ↓ the withdrawal effects significantly; (ii) ↑ appetite (no significant weight gain); (iii) No changes in physiological parameters (blood pressure, pulse and respiratory rate)	[79]

TBARs= Thiobarbituric acid reactive substances, GABA= gamma amino butyric acid, 5-HT= 5 hydroxytryptamine, MDA= malondialdehyde, DA= dopamine, 5HIAA= 5 hydroxyindoleacetic acid, GSH= glutathione peroxidase, SOD= superoxide dismutase, TQ= thymoquinone, Aβ= beta amyloid peptides, ↑=increase, ↓=decrease.