An unusual indole alkaloid with anti-adenovirus and anti-HSV activities from Alstonia scholaris

A novel alkaloid, 17-nor-excelsinidine (1), possessing an unusual 1-azoniatricyclo [4.3.3.0] undecane moiety was isolated from the twigs and leaves of Alstonia scholaris alongside its biogenetically related strictamine (2). The structure and absolute stereochemistry of compound 1 were rigorously determined by a combination of NMR spectroscopy and X-ray crystallography. The 17-nor-excelsinidine (1) and strictamine (2) showed significant inhibitory activity against herpes simplex virus (HSV) and adenovirus (ADV).