Alkaloids of Thalictrum XXVI. New hypotensive and other alkaloids from Thalictrum minus race B.

The roots of T. minus race B have yielded 9 alkaloids, thalirabine (1), thaliracebine (13), thalfine (19), thalfinine (20), thalrugosaminine (22), thalidasine (13), obaberine (24), thaliglucinone (25) and (S)-reticuline (26). The first two, possessing marked hypotensive activity, were assigned complete structures by physical and chemical methods. Thalfine (19) was given S-configuration at its one asymmetric center and was converted to thalfinine (20) and epithalfinine (21), thus the stereochemistry was established at one of the two optically active positions. The other alkaloids were identified by direct comparison with known samples. Antimicrobial testing showed thalirabine, thaliracebine, thalfine, and thalfinine to be active against Mycobacterium smegmatis.