Isoquinolinoisoquinolines

Palmatine is a protoberberine alkaloid found in several plants including Coptis chinensis (Rhizoma coptidis, chinese goldthread), Corydalis yanhusuo, Tinospora cordifolia (gurjo, heart-leaved moonseed), Tinospora sagittata, Phellodendron amurense (amur cork tree), and Stephania yunnanensis.

Phellodendrine is an alkaloid isolated originally from Phellodendron amurense (Rutaceae).

Scoulerine, also known as discretamine and aequaline, is a benzylisoquinoline alkaloid (BIA) that is derived directly from (S)-reticuline through the action of berberine bridge enzyme. It is a precursor of other BIAs, notably berberine, noscapine, (S)-tetrahydropalmatine, and (S)-stylopine, as well as the alkaloids protopine, and sanguinarine. It is found in many plants, including opium poppy, Croton flavens, and certain plants in the genus Erythrina.

Jatrorrhizine is a protoberberine alkaloid found in some plant species, such as Enantia chlorantha (Annonaceae). Synonyms that may be encountered include jateorrhizine, neprotin, jatrochizine, jatrorhizine, and yatrorizine.