Screening of ESR2-targeted anti-postmenopausal osteoporosis chemistry from Rehmanniae Radix Preparata based on affinity ultrafiltration with UPLC-QE-Orbitrap-MS

Rehmanniae Radix Preparata, a processed form of the traditional Chinese medicinal plant Rehmannia glutinosa Libosch, has long been valued for its medicinal properties and use as a food. It is notably effective in treating postmenopausal osteoporosis. This study utilized C18 to separate and purify different concentrations of its eluent streams. MC3T3-E1 cells were utilized to identify the optimal ESR2 activity fraction from various concentrations of Rehmanniae Radix Preparata, using osteoprotegerin (OPG) as an indicator. A single-target affinity ultrafiltration method was created, combining ESR2 affinity ultrafiltration with liquid chromatography-mass spectrometry (LC-MS). Molecular docking validated the interaction mechanism between small molecule ligands and ESR2 protein. These ligands were then tested in MC3T3-E1 cells to assess survival rate, OPG content, and alkaline phosphatase (ALP) activity, an osteogenic differentiation marker. The study showed that Radix Rehmanniae Praeparata effectively combats PMOP, and the combined method of single-target-affinity ultrafiltration-LC-MS with molecular docking offers a robust approach for identifying its anti-PMOP compounds.