The pathogenesis of Alzheimer's disease (AD) has been linked to the deficiency of neurotransmitter acetylcholine (ACh) in the brain, and the main treatment strategy for improving AD symptoms is the inhibition of acetylcholinesterase (AChE) activity. In the present study, we aimed to identify potent AChE inhibitors from Cinnamomum loureirii extract via bioassay-guided fractionation. We demonstrated that the most potent AChE inhibitor present in the C. loureirii extract was 2,4-bis(1,1-dimethylethyl)phenol. To confirm the antiamnesic effects of the ethanol extract of C. loureirii, mice were intraperitoneally injected with the neurotoxin trimethyltin (2.5 mg/kg) to induce cognitive dysfunction, and performance in the Y-maze and passive avoidance tests was assessed. Treatment with C. loureirii extract significantly improved performance in both behavioral tests, suggesting that this extract may be neuroprotective and therefore beneficial in preventing or ameliorating the degenerative processes of AD, potentially by restoring cholinergic function. Key words Alzheimer's disease; Cinnamomum loureirii; acetylcholine; acetylcholinesterase inhibitorThe pathophysiology of Alzheimer's disease (AD), a type of dementia in the elderly, is highly complex. This progressive degenerative disorder was first discovered by Dr. Alois Alzheimer in 1907 and is characterized by incapacitating memory and language losses and impairments in cognitive and behavioral functions. A neuropathological diagnosis of AD includes deposition of extracellular β-amyloid (Aβ) plaques in the cerebral cortex and hippocampus areas, accumulation of intracellular neurofibrillary tangles of abnormally phosphorylated τ, astrocytic gliosis, inflammatory cascades, and degeneration of basal forebrain cholinergic neurons.

One of the critical features of Alzheimer's disease is cognitive dysfunction, which is, in part, due to decreases in acetylcholine (ACh). The ethanol extract of Perilla frutescens was selected for isolating the acetylcholinesterase (AChE) inhibitor based on preliminary screening. In vivo behavioral tests were performed to examine the effects of the P. frutescens extract on trimethyltin chloride-induced impairment of learning and memory in mice. A diet containing P. frutescens extract effectively reversed learning and memory impairment on the Y-maze and passive avoidance tests. To isolate the active compound from the P. frutescens extract, solvent partitioning, silica gel open column chromatography, thin-layer chromatography, and high-performance liquid chromatography were used. The AChE inhibitor was identified as rosmarinic acid.

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To find acetylcholinesterase (AChE) inhibitors for the prevention of neurological disorders, such as Alzheimer's disease, ethanol extracts of promising traditional edible Korean plants were tested. Among them, Rubus coreanus Miquel extract exhibited the most significant AChE inhibitory activity. The effect of R. coreanus extract on trimethyltin-induced memory impairment in mice was investigated using Y-maze and passive avoidance tests. Our results showed that administration of R. coreanus extract significantly improved alternation behavior and step-through latency. In addition, R. coreanus extract was sequentially fractionated, and the purified constituent was determined to be 3,4,5-trihydroxybenzoic acid.

The aim of this study was to search for a novel choline acetyltransferase (ChAT) activator from plants traditionally grown in Korea. An ethanol extract from Chaenomeles sinensis KOEHNE showed the highest ChAT-activating effect in vitro in an assay that used human neuroblastoma cells and [14 C]acetyl-CoA. The active compound was speculated to be stearic acid methyl ester (SAME). In an in vivo experiment, C. sinensis extract and SAME improved trimethyltin (TMT)-induced deficits in learning and memory in mice as assessed by a Y-maze behavioral test and a passive avoidance test. The C. sinensis extract might attenuate the TMT-induced brain disorder. This study suggests that SAME from C. sinensis might be useful in the treatment of Alzheimer's disease.

Response surface methodology (RSM) was utilized to optimize extraction conditions for the acetylcholinesterase inhibitor from Rhodiola sachalinensis. Optimized values for AChE inhibition and extraction yield were 19.41 and 13.35%, respectively, and these were in good agreement with the experimental values from validation, suggesting that RSM is a useful tool.