Protopine is an

alkaloid Alkaloids are a class of basic, naturally occurring organic compounds that contain at least one nitrogen atom. This group also includes some related compounds with neutral and even weakly acidic properties. Some synthetic compounds of similar ...

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 ornamen ...

, ''

Corydalis ''Corydalis'' (from Greek ''korydalís'' "crested lark") is a genus of about 470 species of annual and perennial herbaceous plants in the family Papaveraceae, native to the temperate Northern Hemisphere and the high mountains of tropical eastern ...

'' tubers and other plants of the family

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

, 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 and Central Europe. Descrip ...

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

Reticuline Reticuline is a chemical compound found in a variety of plants including ''Lindera aggregata'', ''Annona squamosa'', and '' Ocotea fasciculata'' (also known as ''Ocotea duckei''). It is based on the benzylisoquinoline structure. Reticuline is o ...

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 the h ...

s and

platelet aggregation Platelets, also called thrombocytes (from Greek θρόμβος, "clot" and κύτος, "cell"), are a component of blood whose function (along with the coagulation factors) is to react to bleeding from blood vessel injury by clumping, thereby ini ...

, and acts as an

analgesic An analgesic drug, also called simply an analgesic (American English), analgaesic (British English), pain reliever, or painkiller, is any member of the group of drugs used to achieve relief from pain (that is, analgesia or pain management). It ...

References

Natural opium alkaloids Alkaloids found in Papaveraceae Benzodioxoles {{heterocyclic-stub

See also

References