Each volunteer was given a single 80-mg oral dose of paeonol (two tablets), three times a day for 2 days (clinical dosage: 120–240 mg/day)

Human umbilical vein endothelial cells (HUVECs, ScienCell, Corte Del Cedro Carlsbad, CA, USA) were cultured in endothelial cell medium (ECM) supplemented with 5% fetal bovine serum, 1% penicillin-streptomycin and 1% endothelial cell growth supplement, maintained at 37 °C and aerated with 5% CO2, 95% O2. The cells (passage 4 to 6) were used when reaching 80-90% confluence. For all experiments, HUVECs were seeded and grown overnight to sub-confluence level before incubation (24 hours), in ECM, with LPS, (0.1, 0.5 and 1μg/mL), hydrogen peroxide (H2O2, 200 μM) and various concentrations of paeonol (0.01, 0.1 and 1 μM,) before collection for apoptosis and protein assays. For other drug treatments, HUVECs were co-treated during 24 hours with one of the following: recombinant BMP4 (100 ng/mL, dissolved in 4 mM HCl with 0.1% BSA), noggin (100 ng/mL, BMP4 antagonist), apocynin (20 μM, NADPH oxidase inhibitor), SP600125 (10 μM, JNK inhibitor), SB202190 (10 μM, p38 MAPK inhibitor), aminoguanidine (100 μM, selective inhibitor of inducible NOS) and TAK242 (1 μM, TLR4 antagonist).