Antimicrobial agents from higher plants. Additional alkaloids and antimicrobial agents from Thalictrum rugosum.

Further study of mother-liquors from ethanolic extracts of Thalictrum rugosum resulted in the identification or partial characterization of 10 alkaloids, bringing the total to 17 characterized in our work on this plant. Five of the new alkaloids were active in vitro against microorganisms. Structures, based upon spectroscopic properties and chemical transformations, are proposed for a new bisbenzylisoquinoline alkaloid named thalrugosaminine, and a protopine alkaloid named protothalipine. A phenanthrene base (thaliglucinone), an aporphine (thalphenine), and three protoberberine bases (columbamine, thalifendine and deoxythalidastine) were identified; three very minor bases of unknown identify were partially characterized.