Theblack seed oil, also known as black cumin oil, is a vegetable oil with multiple benefits. Rich in fatty acids, it is most often obtained by cold pressing from the seeds of the black cumin. From an organoleptic point of view, black seed oil presents itself as an amber liquid releasing a spicy fragrance. Used since antiquity, it accompanies individuals suffering from inflammatory diseases, such as acne, eczema, rosacea or even psoriasis, and can alleviate their symptoms. The anti-inflammatory properties of black seed oil are primarily derived from the thymoquinone it contains.
Thymoquinone has the potential to limit the proliferation of keratinocytes, which is overly active in individuals suffering from psoriasis. This is due to its ability to prevent the synthesis of certain pro-inflammatory cytokines, such as interleukins 2, 6 and 1β (IL-2, IL-6 and IL-1β). In addition to playing a role in the immune response, these cytokines act as a growth factor for keratinocytes. Their inhibition therefore allows for a reduction in keratinisation. Furthermore, thymoquinone inhibits the expression of cyclooxygenase (COX), an enzyme that catalyses the transformation of arachidonic acid into prostaglandin H2. Prostaglandins are inflammatory molecules that increase sensitivity to pain.
Furthermore, this property of inhibiting the proliferation of keratinocytes was demonstrated in a study conducted in vivo on rats. These rats presented lesions similar to those caused by psoriasis. The severity of these lesions was evaluated on a scale of 0 to 12, with 0 corresponding to an absence of lesions and 12 to a significant erythema and a substantial thickening of the skin. For ten days, a cream containing black seed oil, dosed at 5 mg/kg for each rat, was applied to the backs of ten rats, while a cream without black seed oil was applied to the backs of ten other rats. At the end of the experiment, the severity score of the lesions was on average 2 in the rats of the "black seed oil" group and 9 in the rats of the "control" group.
Finally, the thymoquinone found in black seed oil has a proven antioxidant activity and protects skin cells from oxidative stress, which is associated with more severe symptoms of psoriasis. Due to the double bonds present in its chemical structure, thymoquinone can specifically neutralise free radicals by donating an electron, before they attack cellular components. It also increases the activity of superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase, which are antioxidant enzymes playing a key role in the elimination of free radicals.