Abstract
Phytoestrogens derived from plants have attracted the attention of the general public and the medical community due to their potentially beneficial role in relieving menopausal symptoms. The deciduous tree Acer tegmentosum Maxim (Aceraceae) has long been utilized in Korean folk medicine to alleviate many physiological disorders, including abscesses, surgical bleeding, and liver diseases. In order to explore structurally and/or biologically new constituents from Korean medicinal plants, a comprehensive phytochemical study was carried out on the bark of A. tegmentosum. One new phenolic compound with a 1,4-benzodioxane scaffold, isoamericanoic acid B (1), as well as with nine known phenolic compounds (2–10), were successfully isolated from the aqueous extracts of the bark of A. tegmentosum. A detailed analysis using 1D and 2D NMR spectroscopy, electronic circular dichroism (ECD) spectral data, and LC/MS afforded the unambiguous structural determination of all isolated compounds, including the new compound 1. In addition, compounds 2, 4, 5, and 9 were isolated and identified from the bark of A. tegmentosum for the first time. All isolated compounds were tested for their estrogenic activities using an MCF-7 BUS cell proliferation assay, which revealed that compounds 1, 2, and 10 showed moderate estrogenic activity. To study the mechanism of this estrogenic effect, a docking simulation of compound 1, which showed the best estrogenic activity, was conducted with estrogen receptor (ER) -α and ER-β, which revealed that it interacts with the key residues of ER-α and ER-β. In addition, compound 1 had slightly higher affinity for ER-β than ER-α in the calculated Gibbs free energy for 1:ER-α and 1:ER-β. Thus, the present experimental evidence demonstrated that active compound 1 from A. tegmentosum could be a promising phytoestrogen for the development of natural estrogen supplements.
Highlights
Estrogens regulate a variety of physiological functions on organs and tissues such as reproduction, cell growth, and differentiation [1]
After 24 h of incubation, the medium was replaced with experimental charcoal dextran-treated medium (10% CD-fetal bovin serum (FBS) supplemented with phenol red-free dulbecco’s modified eagle medium (DMEM)) containing test compounds at various concentrations
Dried and pulverized A. tegmentosum bark was extracted with distilled water at 90 °C for 10 h a crude aqueous extract
Summary
Estrogens regulate a variety of physiological functions on organs and tissues such as reproduction, cell growth, and differentiation [1]. Previous phytochemical investigations on this plant have reported the isolation of various secondary metabolites with useful bioactivities, such as flavonoids, lignans, and phenolic compounds [9,10]. Phenethyl glycosides and flavonoids were reported to exhibit hepatoprotective activities [9,10]. Korean medicinal plants [14,15,16,17,18], a phytochemical investigation was performed on the bark of A. tegmentosum, which led to the isolation of one new phenolic compound (1) with a 1,4-benzodioxane scaffold, as well as nine known phenolic compounds (2–10) from the aqueous extracts of the bark. The isolation and structural elucidation of compounds 1–10 from the bark of A. tegmentosum, along with their estrogenic effects, were described
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