Anti-cholinesterases and memory improving effects of Vietnamese Xylia xylocarpa

Linh My Thi Lam, Mai Thanh Thi Nguyen, Hai Xuan Nguyen, Phu Hoang Dang, Nhan Trung Nguyen, Hung Manh Tran, Hoa Thi Nguyen, Nui Minh Nguyen, Byung Sun Min, Jeong Ah Kim, Jae Sue Choi, Mao Van Can

Alzheimer's disease (AD) is the most common cause of dementia among the elderly and is characterized by loss of memory and other cognitive functions. An increase in AChE (a key enzyme in the cholinergic nervous system) levels around β-amyloid plaques and neurofibrillary tangles is a common feature of AD neuropathology. Amnesic effects of scopolamine (acetylcholine receptor antagonist) can be investigated in various behavioral tests such as Morris water maze, object recognition, Y-maze, and passive avoidance. In the scope of this paper, we report the anti-AChE, anti-BChE properties of the isolated compound and the in vivo effects of the methanolic extract of Xylia xylocarpa (MEXX) on scopolamine-induced memory deficit. In further phytochemistry study, a new hopan-type triterpenoid, (3β)-hopan-3-ol-28,22-olide (1), together with twenty known compounds were isolated (2-21). Compound 1, 2, 4, 5, 7-9, and 11-13 exhibited potent acetylcholinesterase (AChE) inhibitory activity in a concentration-dependent manner with IC50 values ranging from 54.4 to 94.6 μM. Compound 13 was also shown anti-butyrylcholinesterase (BChE) activity with an IC50 value of 42.7 μM. The Morris water Y-maze, Y-maze, and object recognition test were also carried out. It is noteworthy that MEXX is effective when administered orally to mice, experimental results are consistent with the traditional use of this medicinal plant species.