Fractions from Sea Buckthorn Seeds and Their Bioactive Ingredients as Modulators of Human Blood Platelet Response In Vitro: The Role of Thermal Processing

<b>Background:</b> Given the pivotal role of diet in cardiovascular diseases (CVDs), there is a growing demand for new sources of bioactive phytochemicals that can contribute to CVD prevention and treatment. Previous research has unveiled the cardioprotective properties of several parts of sea buckthorn (<i>Hippophae rhamnoides</i> L.). For example, various fractions isolated from raw and roasted sea buckthorn seeds showed antioxidant properties in vitro. In addition, the serotonin-rich fraction obtained from roasted seed extract had the strongest antioxidant activity. However, it was unclear which chemical constituents contribute to the anti-platelet potential of sea buckthorn seeds. <b>Methods:</b> The anti-platelet activity of two fractions (fraction b and fraction c) from raw sea buckthorn seed extract, two fractions (fraction d and fraction g) from roasted sea buckthorn seed extract, and two chemical compounds-isorhamnetin 3-<i>O</i>-β-glucoside-7-<i>O</i>-α-rhamnoside (a major component of fraction b), and serotonin (5-HT, 5-hydroxytryptamine), present in fraction c was estimated in several in vitro assays. <b>Results:</b> Isorhamnetin 3-<i>O</i>-β-glucoside-7-<i>O</i>-α-rhamnoside significantly inhibited platelet activation. It lowered the exposition of the active form of GPIIb/IIIa on the surface of 20 μM ADP-stimulated platelets by about 26%. It also inhibited the exposition of P-selectin on the surface of 10 and 20 μM ADP-stimulated platelets. In addition, isorhamnetin 3-<i>O</i>-β-glucoside-7-<i>O</i>-α-rhamnoside (at 50 µg/mL) significantly prolonged the time of thrombus formation. The results also indicate that fractions d and g (from roasted seeds) are more effective anti-adhesive factors than fractions from raw sea buckthorn seeds. <b>Conclusions:</b> It can be suggested that sea buckthorn seeds can serve as a new source of anti-platelet compounds (especially derivatives of isorhamnetin) beneficial in CVD prevention and treatment; however, in vivo research is needed to clarify their mechanism of action, physiologically relevant concentrations, and therapeutic potential.