Anti-skeletal Muscle Atrophic Constituents from Fresh Rehmannia Roots and Comparison of Relative Content of Main Ingredients during the Drying Process

The fresh roots extract of Rehmannia glutinosa showed a preventive effect in a dexamethasone-induced C2C12 myotube atrophy model. Bioactivity-guided isolation using centrifugal partition chromatography and prep-HPLC yielded to ten compounds: five phenylethanoid glycosides (1, 2, 4, 5, and 7), three iridoids (6, 9, and 10), one phenylpropanoid (3) and one sesquiterpene glycoside (8). Their chemical structures were elucidated as echinacoside (1), jionoside A1 (2), ferulic acid (3), verbascoside (4), jinoside B1 (5), 6-O-E-feruloyl ajugol (6), martynoside (7), aeginetic acid 5-O-β-D-quinovoside (8), aeginetoyl ajugol 5&quot-O-β-D-qunovoside (9), and rehmaglutinoside F (10) by spectroscopic analysis. Among them, compounds 7 and 9 demonstrated preventive effects against dexamethasone-induced skeletal muscle atrophy in C2C12 myotubes. Furthermore, the during the drying process of fresh R. glutinosa, the relative content ratio of compound 6 increased by 7.8 fold, while the levels of compounds 5, 6, 8, and 9 decreased by more than 50%.