Chemical constituents of the Ajuga multiflora bunge and their protective effects on dexamethasone-induced muscle atrophy in C2C12 myotubes

Ajuga multiflora Bunge is a perennial ornamental herb and has been used for the treatment of fever in Korean folk medicine. In the course of searching for protective agents associated with the potential of A. multiflora against dexamethsone (DEX)-induced muscle atrophy, a new phytoecdysteroid, 29-hydroxyprecyasterone (1), together with four known compounds (2-5), were isolated from A. multiflora. The structures of the compounds were determined by spectroscopic analyses, including 1D-, 2D-NMR and HR-MS interpretation. To elucidate the effects of obtained compounds on DEX-induced muscle atrophy, the myotubes diameter, myosin heavy chain (MyHC) positive area, and fusion index were evaluated by immunofluorescence staining. Overall, each compound treatment effectively prevented the atrophic myotubes through an increase of MyHC-positive myotubes and the number of nuclei. Particularly, the measurement of myotube diameter showed that compounds 1 and 5 treatment significantly alleviated the myotube thickness.