Abstract

Platelets are small circulating anucleated cells, resulting from the fragmentation of megakaryocytes. They are directly involved in primary hemostasis, where they are among the first elements to intervene in stopping bleeding. Platelet count or functional alteration was reported to be correlated to different types of diseases. Since antiquity, plants have been used to cure panoply of diseases. Nigella sativa, black cumin, is an annual Mediterranean plant. Nigella sativa's main essential oil constituent, thymoquinone (30 %-48 %) is responsible for a number of its biological activity. Various drugs and plant substances can induce thrombocytopenia. Some studies describe a dose and time-dependent decrease of platelet count induced by consumption of these substances. Thymoquinone is a quinine-like compound; quinines are involved in drug-induced immune thrombocytopenia. Indeed, human consumption and rat administration of black seed oil for 4 and 12 w, respectively, induce thrombocytopenia. To date, the thymoquinone effect on platelets is not fully understood. Here we bring new elements on the effects of thymoquinone on platelet aggregation. Our results show that thymoquinone by itself is able to induce platelet aggregation, but needs a relatively long exposure (28 min). We also show that thymoquinone-induced platelet aggregation is probably mediated through cytochrome metabolites but mainly via the mitochondrial pathway. Results demonstrate that platelets pre-incubation with thymoquinone abrogate thrombin-induced platelet aggregation in a concentration-dependent manner. In conclusion, black seeds and thymoquinone consumption as nutritional complement or as alternative medicine should be in low concentration and under phyto-specialists or medical supervision.