Alsmaphorazines A and B, novel indole alkaloids from alstonia pneumatophora

摘要

Two novel indole alkaloids, alsmaphorazines A and B, were isolated from the leaves of Alstonia pneumatophora (Apocynaceae), and their structures were determined on the basis of the 2D NMR and MS spectral analysis. These alkaloids possessed a new skeleton consisting of an 1,2-oxazinane and an isoxazolidine chromophore. The absolute configuration of alsmaphorazine B was determined by using CD spectral analysis. Alsmaphorazine A inhibited the NO production in the LPS-stimulated J774.1 cells dose-dependently without affecting the cell viability.