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Acer tegmentosum, a deciduous tree belonging to Aceraceae, has been used in traditional oriental medicine for treating hepatic disorders, such as hepatitis, cirrhosis, and liver cancer. We evaluated the estrogen-like effects of A. tegmentosum using an estrogen receptor (ER)-positive breast cancer cell line, namely MCF-7, to identify potential phytoestrogens and found that an aqueous extract of A. tegmentosum promoted cell proliferation in MCF-7 cells. Five phenolic compounds (1–5) were separated and identified from the active fraction using bioassay-guided fractionation of crude A. tegmentosum extract and phytochemical analysis. The chemical structures of the compounds were characterized as vanillic acid (1), 4-hydroxy-benzoic acid (2), syringic acid (3), isoscopoletin (4), and (E)-ferulic acid (5) based on the analysis of their nuclear magnetic resonance spectra and liquid chromatography-mass spectrometry data. All five compounds were evaluated using an E-screen assay for their estrogen-like effects on MCF-7 cells. Among the tested compounds, only 4-hydroxy-benzoic acid (2) promoted the proliferation of MCF-7 cells, which was mitigated by the ER antagonist, ICI 182,780. The mechanism underlying the estrogen-like effect of 4-hydroxy-benzoic acid (2) was evaluated via western blotting analysis to determine the expression levels of extracellular signal-regulated kinase (ERK), phosphoinositide 3-kinase (PI3K), serine/threonine kinase (AKT), and ERα. Our results demonstrated that 4-hydroxy-benzoic acid (2) induced the increase in the protein expression levels of p-ERK, p-AKT, p-PI3K, and p-Erα, concentration dependently. Collectively, these experimental results suggest that 4-hydroxy-benzoic acid (2) is responsible for the estrogen-like effects of A. tegmentosum and may potentially aid in the control of estrogenic effects during menopause.

This research was the first to investigate the variations of conjugated linoleic acid (CLA), isoflavone, digestive enzyme inhibition, and antioxidant properties in hydrolysate soybean milks under fermentation using Lactobacillus plantarum P1201. The average CLA contents increased significantly in the range of ND → 0.91–1.75 mg/g during fermentation, whereas the isoflavone glucosides were markedly reduced (1570.01 → 548.41 µg/g, 65%) with the increase of aglycone contents (58.75 → 453.45 µg/g, 7.7 times). In particular, daidzein and cis-9, trans-11 CLA exhibited the predominant compositions (>50% and >90%) with considerable increases in fermented soybean milks. Total phenolic and flavonoid contents also slightly increased. Interestingly, fermented soybean extracts possessed potent α-glucosidase and pancreatic lipase inhibitory effects with average 32.4 → 55.5% and ND → 43.4% at a concentration of 500 μg/ml. Moreover, the antioxidant properties against three radicals increased markedly as the following order: ABTS (46.1 → 87.6%) > DPPH (38.8 → 77.4%) > hydroxyl (15.6 → 47.0%). Therefore, fermented hydrolysate milks might have attributed to enhance the soybean value.