Effects of Protocatechuic Acid on Endothelial Function and HDL Functionality in Hypercholesterolemic Subjects: A Randomized Double-Blind Placebo-Controlled Trial

Figures

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  Figure 1. A summary of the study design. (A) The schematic diagram of the study design. (B) The flowchart of enrollment and randomization.

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  Figure 2. HDL-mediated eNOS activation was functionally reliant on EC-7KCEC. (A,B) HAECs were untreated or transfected with control siRNA (siCtr) or siRNA directed against ABCG1 (siABCG1) with 100 nM for 24 h. ABCG1 knockdown efficiency was then determined by Western blot (A) and qRT-PCR (B) assays. (C) 7-KC-loaded HAECs that had been transfected with ABCG1 siRNA or control siRNA were incubated with HDL isolated from participants after dietary intervention for 16 h. eNOS activities in HAECs was then measured. The pooled serum from all subjects at the baseline was served as the control group. (D,E) Correlation between the changes in eNOS activity of HDL and the changes in EC-7KCEC of HDL in PCA (D) and Con (E). Data were mean ± SEM (n = 6, A,B; n = 148, C–E). * p < 0.05, NS indicates not significant. 7-KC, 7-ketocholesterol; ABCG1, ATP-binding cassette transporter G1; Con, control; HAECs, human aortic endothelial cells; EC-7KCEC, cultured human aortic endothelial 7-ketocholesterol efflux capacity; eNOS, endothelial nitric oxide synthase; HDL, high-density lipoprotein.

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  Figure 3. The correlation between the changes in eNOS activity of HDL and the changes in HDL subclass distribution. The correlation between the changes in eNOS activity of HDL and the changes in the variation of HDL3 (A,B); the variation in HDL2 (C,D) and the variation in pre-β-HDL (E,F) are shown. Spearman correlation coefficients are noted for each plot. HDL, high-density lipoprotein; eNOS, endothelial nitric oxide synthase; PCA, protocatechuic acid.

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  Figure 4. The correlation between the changes in eNOS activity of HDL and the changes in brachial artery FMD and cGMP. The correlation between the changes in eNOS activity of HDL and the changes in brachial artery FMD (A,B) and cGMP (C,D) are shown. Spearman correlation coefficients are noted for each plot. cGMP, cyclic guanosine monophosphate; eNOS, endothelial nitric oxide synthase; FMD, flow-mediated dilation; PCA, protocatechuic acid.