Xanthohumol, a Prenylated Flavonoid from Hops (Humulus lupulus), Prevents Platelet Activation in Human Platelets
Figure 5
Regulation of platelet aggregation, nitrate formation, and hydroxyl radical (OH●) formation by xanthohumol (XN). ((a) and (b)) Washed platelets ( cells/mL) were preincubated with 10 μM prostaglandin E1 (PGE1), 10 μM nitroglycerin (NTG), or 3 μM XN in the absence or presence of 20 μM ODQ or 100 μM SQ22536, followed by the addition of 1 μg/mL collagen to trigger platelet aggregation. Profiles are representative examples of three similar experiments. On the other hand, (c) washed platelets (109 cells/mL) were incubated with 10 μM nitroglycerin (NTG), and 1.5 and 3 μM XN. Cells were then collected, and subcellular extracts were analyzed for nitrate formation as described in Section 2. Data are presented as the means ± S.E.M. (). ***, compared to the resting group. (d) For the electron spin resonance (ESR) study, washed platelets (3.6 × 108 cells/mL) were incubated with (A) Tyrode’s solution only (resting group), or platelets were preincubated with (B) the control (0.5% DMSO), (C) 1.5 μM, or (D) 3 μM XN followed by the addition of 1 μg/mL collagen to trigger hydroxyl radical formation. Spectra are representative examples of three similar experiments. An asterisk (*) indicates the formation of hydroxyl radicals.
