A Study on the Inhibition of AChE Activity by Ethanolic Extract of Tibet Wild Gymnadenia crassinervis and Its Protective and Reparative Effects on Aβ25−35-Induced Cell Injury

It is of great significance to develop natural active substances for treating Alzheimer’s disease (AD). We constructed an AD cell model using Aβ₂₅₋₃₅-induced PC12 cells to assess isolated components from Tibet wild Gymnadenia crassinervis protective and reparative effects against Aβ₂₅₋₃₅-induced cell injury. The results indicated that the active fraction extracted and isolated from Gymnadenia crassinervis strongly inhibited acetylcholinesterase (AChE) with an excellent IC₅₀ value as low as 135.86 ± 5.59 μg/mL. The main compound of the Gymnadenia crassinervis active fraction was preliminarily identified as dactylorhin A by LC-MS. The high-concentration group, treated with 10 μg/mL of the Gymnadenia crassinervis active fraction, exhibited significantly protective effects, the treatment of which enhanced cell viability and mitigated cell shrinking induced by Aβ₂₅₋₃₅. The ROS level and MDA content in the high-concentration group cells decreased by approximately 28% and 30%, respectively, while the activities of SOD and CAT even increased by about 92% and 221%, respectively. In addition, Western blotting analysis showed that the Gymnadenia crassinervis active fraction inhibited apoptosis. Therefore, these findings suggest that the Gymnadenia crassinervis active fraction can repair Aβ₂₅₋₃₅-induced cell injury, protect against Aβ toxicity, and hold potential in both preventive and therapeutic aspects of AD.