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Acanthopanax trifoliatus is a plant that has been traditionally used in Thailand as a vegetable and a tonic. This study investigated effects of the aqueous extract of its leaves (ATL) on cognitive and emotional deficits using an olfactory bulbectomized mouse (OBX) model. OBX mice were treated daily with ATL (250 and 500 mg/kg, p.o.) 3 days after OBX. Antidementia drug tacrine (2.5 mg/kg/day) and antidepressant drug imipramine (10 mg/kg/day) were given i.p. as reference drugs. OBX significantly impaired cognitive behavior in a novel object recognition test and a modified Y-maze test and induced depression-like behavior in a tail suspension test. ATL and tacrine treatment attenuated OBX-induced cognitive deficits, whereas ATL and imipramine improved OBX-induced depression-like behavior. Neurochemical studies conducted after completing behavioral experiments demonstrated that OBX downregulated the expression levels of cholinergic marker genes encoding choline acetyltransferase and muscarinic M1 receptor in a manner reversed by ATL and tacrine. Moreover, ATL and tacrine administration inhibited the ex vivo activity of acetylcholinesterase in the brain. These findings suggest that ATL is beneficial for the treatment of cognitive and emotional deficits related to dementia with depressive symptoms and that the antidementia effect of ATL is mediated by normalizing the function of central cholinergic systems.

Objective: The aim of this study was to investigate the antioxidant activity of extracts of various parts of Acanthopanax trifoliatus obtained by different extraction methods. The total phenolic and flavonoid contents of the extracts were also determined. Materials and Methods: The leaves, stems, stem bark, roots and root bark of A. trifoliatus were extracted separately using decoction, maceration and refluxing methods. The extracts were analysed for free-radical-scavenging activity using the 1,1-diphenyl-2-picryl-hydrazyl scavenging assay and the thiobarbituric-acid-reactive substance method for the inhibition of lipid peroxidation of a rat brain homogenate. Total phenolic and total flavonoid contents of the extracts were measured by UV spectrophotometry. Results: The leaf decoction extracts possessed a significantly stronger antioxidant activity as revealed by both methods. Total phenolic and flavonoid contents of the extracts ranged from 2.16 to 21.79 g% chlorogenic acid equivalent and from 0.37 to 9.61 g% rutin equivalent, respectively. Analysis of the leaf decoction extract, which exhibited the most potent antioxidant activity, by thin-layer chromatography revealed flavonoid and polyphenolic compounds corresponding to rutin and chlorogenic acid. Conclusion: The leaf aqueous extracts showed a high level of antioxidative activity and contained high levels of both phenolic and flavonoid compounds. The magnitude of antioxidant activity corresponded with the level of phenolic and flavonoid compounds.