Extraction and isolation of polyhydroxy triterpenoids from Michx. fruit with anti-acetylcholinesterase and neuroprotection properties.

fruit, at present, is becoming increasingly popular as a functional foodstuff with several nutritional and medicinal properties. To explore the acetylcholinesterase (AChE) inhibitory activity of extracts from the Michx. fruit (RLMF), a simple and efficient enrichment purification technology based on microwave-assisted extraction (MAE) and multi vacuum extraction columns (VEC) was applied to screen and identify triterpenoids (TTs) in the RLMF extracts. The MAE conditions were optimized using the Box-Behnken design (BBD) with a quadratic regression model and the response surface method (RSM). The optimum conditions were as follows: ethanol concentration, 69%; extraction time, 12 min; ratio of liquid to raw material, 26 : 1 mL g; and microwave power, 528 W. Under these conditions, the maximum content of triterpenoids reached 62.48 ± 0.25 mg g, which was close to the predicted value of 62.69 mg g. In addition, two pure polyhydroxy triterpenoids: 2α,3β,19α,23-tetrahydroxyurs-12-en-28-oic acid (1) and 2α,3β,19α,23-tetrahydroxyurs-12-en-28-oic acid-28--β-d-glucopyrannoside (2) were isolated and enriched to more than 500 mg by a multi VEC method. Furthermore, the quantities of compounds 1 and 2 from RLMF were 5.36 and 10.37 mg g, respectively, as determined using HPLC. These compounds were further assessed for acetylcholinesterase inhibitory and neuroprotection properties. The results showed that 1 and 2 showed potent AChE inhibitory activities with IC values of 29.22 and 45.47 μg mL, respectively. At high concentration, compounds 1 and 2 produced a 92% and 89% inhibition on the target enzyme, which was consistent with docking results between AChE and each isolate. Moreover, both 1 and 2 exhibited potential neuroprotective activities against HO-induced SHSY5Y cell death.