Natural products as a source of Alzheimer's drug leads

As acetylcholinesterase (AChE) inhibitors are an important therapeutic strategy in Alzheimer’s disease, efforts are being made in search of new molecules with anti-AChE activity. The fact that naturally-occurring compounds from plants are considered to be a potential source of new inhibitors has led to the discovery of an important number of secondary metabolites and plant extracts with the ability of inhibiting the enzyme AChE, which, according to the cholinergic hypothesis, increases the levels of the neurotransmitter acetylcholine in the brain, thus improving cholinergic functions in patients with Alzheimer’s disease and alleviating the symptoms of this neurological disorder. This review summarizes a total of 128 studies which correspond to the most relevant research work published during 2006-2012 (1st semester) on plant-derived compounds, plant extracts and essential oils found to elicit AChE inhibition.

Natural AChE Inhibitors from Plants and their Contribution to Alzheimer’s Disease Therapy

http://www.zespoldowna.info/files/HuperzineA/publikacje/12.pdf

Huperzine A from Huperzia species--an ethnopharmacolgical review.

Lycopodium alkaloids are unique heterocyclic alkaloids having C 11 N, C 15 N 2 , C 16 N, C 16 N 2 , C 22 N 2 , and C 27 N 3 types from genus Lycopodium and have attracted great interest from biogenetic and biological points of view as well as providing challenging targets for total synthesis This review covered the structure elucidation and biological activity of new Lycopodium alkaloids and total synthesis of some Lycopodium alkaloids reported in the literature from 2004 to July in 2008

The lycopodium alkaloids

The isoxazolidine ring represents one of the privileged structures in medicinal chemistry, and there have been an increasing number of studies on isoxazolidine and isoxazolidine-containing compounds. Optimization of the 1,3-dipolar cycloaddition (1,3-DC), original methods including electrophilic or palladium-mediated cyclization of unsaturated hydroxylamine, has been developed to obtain isoxazolidines. Novel reactions involving the isoxazolidine ring have been highlighted to accomplish total synthesis or to obtain bioactive compounds, one of the most significant examples being probably the thermic ring contraction applied to the total synthesis of (±)-Gelsemoxonine. The unique isoxazolidine scaffold also exhibits an impressive potential as a mimic of nucleosides, carbohydrates, PNA, amino acids, and steroid analogs. This review aims to be a comprehensive and general summary of the different isoxazolidine syntheses, their use as starting building blocks for the preparation of natural compounds, and their m...

Koichiro Koyama

Papers

Alsmaphorazines A and B, novel indole alkaloids from Alstonia pneumatophora.

Carinatumins A-C, new alkaloids from Lycopodium carinatum inhibiting acetylcholinesterase.

Alstilobanines A-E, new indole alkaloids from Alstonia angustiloba

Alpneumines A–H, new anti-melanogenic indole alkaloids from Alstonia pneumatophora

Lycochinines A–C, novel C27N3 alkaloids from Lycopodium chinense