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Cholesterol-lowering activity of adzuki bean (Vigna angularis) polyphenols

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Adzuki beans (ABs; Vigna angularis) were reported to show potential for prevention of cholesterol absorption and lowering of the blood cholesterol level. However, the main active compounds and some cellular effects remain unknown. In this study, we evaluated the potential cholesterol-lowering effects of (+)-catechin 7-O-β-d-glucopyranoside (C7G) and (+)-epicatechin 7-O-β-d-glucopyranoside (E7G), identified as abundant polyphenols in ABs.

Methods and results

To investigate the cholesterol-lowering activity in vitro, cholesterol micelles, bile acids, and Caco-2 cells as an intestinal model were used in the study. C7G and E7G each inhibited micellar solubility in a dose-dependent manner, and their inhibitory activity was as strong as that of (+)-catechin (IC50 values: C7G, 0.23 ± 0.03 mg/ml; E7G, 0.22 ± 0.02 mg/ml; (+)-catechin, 0.26 ± 0.11 mg/ml). The AB polyphenols showed binding activity toward bile acids and changed them into an insoluble form. When Caco-2 cells were treated with C7G or E7G, the amount of incorporated cholesterol was significantly decreased compared with vehicle-treated control cells, and no cytotoxicity was observed under the experimental conditions used. Meanwhile, quantitative real-time PCR revealed that the mRNA level of the cholesterol transporter NPC1L1 remained unchanged in the treated cells.


Taken together, the present findings suggest that C7G and E7G are the main active compounds in ABs, and have the ability to inhibit micellar solubility, bind to bile acids, and suppress cholesterol absorption. The present study supports the health benefits of ABs as a medicinal food and the application of AB polyphenols as medicinal supplements to suppress cholesterol elevation.

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We thank H. Ishikawa (Mie University) for technical contributions to the study.


This research did not receive any specific grants from funding agencies in the public, commercial, or not-for-profit sectors.

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Authors and Affiliations



KK, MN, and HU conceived and designed the study. SG and EK carried out the experiments. KK, SG, and EK performed the data analysis. MN and MN prepared the facilities and instruments. KK and HU wrote the manuscript. All authors read and approved the final manuscript.

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Correspondence to Kenji Kuriya.

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Supplementary file1 (TIF 2096 kb) Supplementary Fig. 1 HPLC chromatogram of ABE. ABE (50 μg) was analyzed by HPLC using a C18 column and ultraviolet detection at 210 nm. The mobile phases were ultrapure water and methanol (0–15 min, 100% ultrapure water; 15–45 min, 100% ultrapure water to 100% methanol), and the flow rate was 1 ml/min. The identified compounds were as follows: peak I, C7G; peak II, (+)-catechin; peak III, E7G


Supplementary file2 (TIF 2270 kb) Supplementary Fig. 2 Effects of prolonged treatment with C7G or E7G on NPC1L1 mRNA expression. RNA was extracted from Caco-2 cells treated with C7G or E7G at a final concentration of 100 µg/ml for 72 h. The relative expression of NPC1L1 mRNA was calculated as a percentage relative to the vehicle control (CNT) and normalized by β-actin mRNA. Data are shown as mean ± SE of triplicate determinations in three independent experiments. No significant differences were found compared with CNT

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Kuriya, K., Goto, S., Kobayashi, E. et al. Cholesterol-lowering activity of adzuki bean (Vigna angularis) polyphenols. Mol Biol Rep 50, 5575–5584 (2023).

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