Additional alkaloids were obtained from T. rugosum and characterized by spectral methods. These minor constituents were obtained from the tertiary alkaloid fractions by extensive chromatography. The ether-soluble nonphenolic fraction gave oxyberberine (1), thalrugosinone Í2), thalicthuberine (3), obaberine (4), protopine (5) and neothalibrine (6). The ether-soluble phenolic fraction afforded aromoline (8) and coryalline (9): while the chloroform-soluble fraction yielded rugosinone (10), noroxyhydrastinine (12) and 1,2-dihydro-6,7-methylenedioxy-1-oxoisoquinoline (13). All are new alkaloids for the source, with thalrugosinone (2), rugosinone (10) and 1,2-dihydro-6,7-methylenedioxy-1-oxoisoquinoline (13) also new natural products. Antimicrobial activity is reported for nine alkaloids and one derivative. © 1980, American Chemical Society. All rights reserved.