Experimental and molecular docking studies of estrogen-like and anti-osteoporosis activity of compounds in Fructus Psoraleae

Fructus Psoraleae (FP), dry mature fruits of Cullen corylifolium (L.) Medik., has been used clinically to treat kidney yang deficiency-induced impotence, asthma and cold pain in waist and knee caused by kidney deficiency. A study of the source of the significant kidney-enhancing effect of FP revealed that it may be due to its strong estrogen-like activity.This study aimed to investigate the estrogen-like activity of the FP extract and 13 bioactive compounds in it, as well as the mechanisms underlying their estrogen-like and anti-osteoporosis activities.The estrogen-like activities of the 75% ethanol-only FP extract, and 75% ethanol plus petroleum ether, ethyl acetate, n-butanol or water FP extracts were each measured using Cell Counting Kit-8 (CCK-8) and luciferase reporter gene assays. The compounds were identified by high-performance liquid chromatography analysis. The activation of estrogen receptor signaling by the compounds was compared with that by estradiol (E2) using the molecular docking software MOE-Dock 2008.10. The activation of the ER-Wnt-β-catenin signaling pathway was investigated using an alkaline phosphatase (ALP) assay, qPCR analysis and Western blot analysis.The results revealed that the 75% ethanol plus ethyl acetate extract showed the highest estrogen-like activity among the four 75% ethanol extract fractions (further extracted with petroleum ether, ethyl acetate, n-butanol or water). Some compounds in FP showed strong estrogenic effect and anti-osteoporosis activity, and activated the Wnt-β-catenin pathway. The isoflavone compound was the most active.This study demonstrated that FP has a strong estrogen-like activity and some of its component compounds have anti-osteoporosis activity by activating the ER-Wnt-β-catenin signaling pathway. Our detections provide a new insight into the mechanisms underlying the estrogen-like and anti-osteoporosis activities of FP, as well as a better understanding of structure effects.