Alzheimer's disease (AD) is a progressive neurodegenerative disease, wherein a progressive loss of cholinergic synapses occurs in hippocampus and neocortex. Decreased concentration of the neurotransmitter, acetylcholine (ACh), appears to be critical element in the development of dementia, and the most appropriate therapeutic approach to treat AD and other form of dementia is to restore acetylcholine levels by inhibiting both major form of cholinesterase: Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). Consequently, researches have focused their attention towards finding cholinesterase inhibitors from natural products. A large number of such inhibitors have been isolated from medicinal plants. This review presents a comprehensive account of the advances in field of cholinesterase inhibitor phytoconstituents. The structures of some important phytoconstituents (collected through www.Chemspider.com) are also presented and the scope for future research is discussed.

The methanolic extract of the leaves of Peltophorum vogelianum (Caesalpiniaceae) afforded a new phytoconstituent, 2-methoxy-4,5-dihydroxy-1(7,8-dihydroxyethylene)-8-beta-D-glucuropyranoside named as peltophorumyl-beta-D-glucuropyranoside (5), along with four known phytoconstituents, 1-pentatriacontanol (1), friedelin (2), beta-sitosterol (3) and beta-sitosterol-beta-D-glucopyranoside (4), which have not been isolated previously from this plant. Their structures were established on the basis of chemical and physical evidence (IR, 1H-NMR, 13C-NMR, DEPT, HSQC, HMBC and MS). Moreover, compound 5 showed significant antimicrobial activity.

The methanolic extract of the leaves of Xylosma longifolium afforded a new flavonodic compound named as Kaempferol-3-β-xylopyranoside-4'-α-rhamnoside along with Kaempferol, Quercetin, Kaempferol-3-rhamnoside, Quercetin-3-rhamnoside. Their structures were established on the basis of chemical and physical evidences (IR, 1 H NMR, and MS data). It was also screened for their antimicrobial activity.

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The benzene extract of the leaves of Ficus benjamina (variety comosa) afforded a new triterpene, named serrat-3-one (Fc-2), along with the known phytoconstituents pentacontanyl decanoate (Fc-1), friedelin and beta-sitosterol. Their structures were established on the basis of chemical and physical evidence (IR, (1)H NMR, (13)C NMR and MS). The aqueous and alcoholic extracts of leaves of F. bejamina showed significant antinociceptive activity in an analgesiometer test.