Protopine is an

alkaloid Alkaloids are a broad class of natural product, naturally occurring organic compounds that contain at least one nitrogen atom. Some synthetic compounds of similar structure may also be termed alkaloids. Alkaloids are produced by a large varie ...

occurring in

opium poppy ''Papaver somniferum'', commonly known as the opium poppy or breadseed poppy, is a species of flowering plant in the family Papaveraceae. It is the species of plant from which both opium and poppy seeds are derived and is also a valuable orname ...

, ''

Corydalis ''Corydalis'' (from Greek ''korydalís'' " crested lark") is a genus of about 540 species of annual and perennial herbaceous plants in the family Papaveraceae, native to the temperate Northern Hemisphere and the high mountains of tropical ...

'' tubers and other plants of the family

papaveraceae The Papaveraceae, informally known as the poppy family, are an economically important family (biology), family of about 42 genera and approximately 775 known species of flowering plants in the order Ranunculales. The family is cosmopolitan dis ...

, like ''

Fumaria officinalis ''Fumaria officinalis'', the common fumitory, drug fumitory or earth smoke, is a herbaceous annual flowering plant in the poppy family Papaveraceae. It is the most common species of the genus ''Fumaria'' in Western Europe, Western and Central Eur ...

''. Protopine is metabolically derived from the benzylisoquinoline alkaloid (''S'')-

Reticuline Reticuline is an alkaloid found in opium and a variety of plants including ''Lindera aggregata'', ''Annona squamosa'', and ''Ocotea#Selected species, Ocotea fasciculata'' (also known as ''Ocotea duckei''). Experiments in rodents suggest reticuli ...

through a progressive series of five enzymatic transformations: 1) berberine bridge enzyme to (''S'')-Scoulerine; 2) (''S'')-cheilanthifoline synthase/CYP719A25 to (''S'')-Cheilanthifoline; 3) (''S'')-stylopine synthase/CYP719A20 to (''S'')-Stylopine; 4) (''S'')-tetrahydroprotoberberine ''N''-methyltransferase to (''S'')-''cis''-''N''-Methylstylopine; and ultimately, 5) ''N''-methylstylopine hydroxylase to protopine. It has been found to inhibit

histamine H1 receptor The H1 receptor is a histamine receptor belonging to the family of rhodopsin-like G-protein-coupled receptors. This receptor is activated by the biogenic amine histamine. It is expressed in smooth muscles, on vascular endothelial cells, in ...

s and

platelet aggregation Platelets or thrombocytes () are a part of blood whose function (along with the coagulation factors) is to react to bleeding from blood vessel injury by clumping to form a blood clot. Platelets have no cell nucleus; they are fragments of cytop ...

, and acts as an

analgesic An analgesic drug, also called simply an analgesic, antalgic, pain reliever, or painkiller, is any member of the group of drugs used for pain management. Analgesics are conceptually distinct from anesthetics, which temporarily reduce, and in s ...

References

{{Components of Opium Alkaloids found in Papaveraceae Natural opium alkaloids Methylenedioxyphenethylamines

See also

References