Response of human blood platelets to preparations from leaves of Paulownia Clon in Vitro 112.

Paulownia Clon in Vitro 112, also called the Oxytree, is a fast-growing hybrid of two trees belonging to the Paulowniaceae family - P. elongata and P. fortunei. It demonstrates a wide range of biological effects (including antioxidant, anti-inflammatory, antibacterial, and neuroprotective) due to the high concentration of secondary metabolites. Our previous results showed an in vitro antioxidant and antiplatelet activity of the extract and four fractions (A-D) from the leaves of Paulownia Clon in Vitro 112 in human plasma and washed blood platelets. Here, we used a microchip flow chamber-based thrombus formation analysis system (T-TAS) and flow cytometry to assess the anticoagulant and antiplatelet activity of the extract and four fractions with different chemical content (A-D) from Paulownia Clon in Vitro 112 leaves in human whole blood. Two tested fractions: fraction C and D (at the concentrations of 5 and 50 μg/mL) inhibited the exposition of the active form of GPIIb/IIIa (integrin αIIb β3 ) on the surface of blood platelets stimulated by ADP and collagen. The antiplatelet activity of fraction C is likely due to its high verbascoside content and the presence of apigenin's derivatives. Fraction D contains triterpenoids, including ursolic, pomoleic, and maslinic acid, which could be responsible for decreased activation of ADP- and collagen-stimulated blood platelets. These results suggest that fractions C and D might be promising sources of phytochemicals with antiplatelet activity, which are important for prophylaxis and treatment of cardiovascular diseases associated with hyperactivation of blood platelets. However, further research is needed to ascertain which exact compounds and mechanisms are responsible for this phenomenon.