Pd-Catalyzed Direct Diversification of Natural Anti-Alzheimer's Disease Drug: Synthesis and Biological Evaluation of N-Aryl Huperzine A Analogues

J Nat Prod. 2021 Aug 27;84(8):2374-2379. doi: 10.1021/acs.jnatprod.1c00600. Epub 2021 Aug 16.

Abstract

The first systematic direct diversification of a complex natural product by metal-catalyzed N-H functionalization was carried out. A new series of N-(hetero)aryl analogues (1-32) of the natural anti-Alzheimer's disease drug huperzine A (HPA) was prepared via palladium-catalyzed Buchwald-Hartwig cross-coupling reactions of HPA with various aryl bromides in good yields. Most of the N-aryl-huperzine A (N-aryl-HPA) analogues showed good acetylcholinesterase (AChE) inhibitory activity in in vitro experiments. Three arylated huperzine A analogues (14, 19, and 30) exhibited stronger anti-AChE activity than HPA. The 5-methoxy-2-pyridyl analogue (30) displayed the most potent AChE inhibition activity, with an IC50 value of 1.5 μM, which was 7.6-fold more active than HPA. Compound 30 also exhibited better neuroprotective activity for H2O2-induced damage in SH-SY5Y cells than HPA. Structure-activity relationship analysis suggested that the electron density of the installed aromatic ring or heteroaromatic ring played a significant role in inducing the AChE inhibition activity. Overall, compound 30 showed the advantages of easy synthesis, high potency and selectivity, and improved neuroprotection, making it a potential huperzine-type lead compound for Alzheimer's disease drug development.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alkaloids / chemical synthesis
  • Alkaloids / pharmacology*
  • Alzheimer Disease / drug therapy*
  • Blood-Brain Barrier
  • Catalysis
  • Cell Line, Tumor
  • Cholinesterase Inhibitors / chemical synthesis
  • Cholinesterase Inhibitors / pharmacology*
  • Humans
  • Molecular Docking Simulation
  • Molecular Structure
  • Neuroprotective Agents / chemical synthesis
  • Neuroprotective Agents / pharmacology*
  • Palladium / metabolism*
  • Sesquiterpenes / chemical synthesis
  • Sesquiterpenes / pharmacology*
  • Structure-Activity Relationship

Substances

  • Alkaloids
  • Cholinesterase Inhibitors
  • Neuroprotective Agents
  • Sesquiterpenes
  • huperzine A
  • Palladium