{{chembox | Name = Scoulerine | ImageFile = Scoulerine-S.png | ImageName = Scoulerine | IUPACName = 3,10-Dimethoxyberbine-2,9-diol | SystematicName = (13a''S'')-3,10-Dimethoxy-5,8,13,13a-tetrahydro-6''H''-isoquinolino[3,2-''a'']isoquinoline-2,9-diol | OtherNames = (''S'')-Scoulerin; Discretamine; Aequaline |Section1={{Chembox Identifiers | ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} | ChemSpiderID = 388725 | ChEMBL_Ref = {{ebicite|correct|EBI}} | ChEMBL = 1235966 | PubChem = 439654 | StdInChI_Ref = {{stdinchicite|correct|chemspider}} | StdInChI = 1S/C19H21NO4/c1-23-17-4-3-11-7-15-13-9-16(21)18(24-2)8-12(13)5-6-20(15)10-14(11)19(17)22/h3-4,8-9,15,21-22H,5-7,10H2,1-2H3/t15-/m0/s1 | StdInChIKey_Ref = {{stdinchicite|correct|chemspider}} | StdInChIKey = KNWVMRVOBAFFMH-HNNXBMFYSA-N | CASNo_Ref = {{cascite|correct|CAS}} | CASNo = 6451-73-6 | ChEBI_Ref = {{ebicite|correct|EBI}} | ChEBI = 17129 | KEGG_Ref = {{keggcite|correct|kegg}} | KEGG = C02106 | SMILES = Oc1c4c(ccc1OC)C[C@H]3c2c(cc(OC)c(O)c2)CCN3C4 }} |Section2={{Chembox Properties | C=19 | H=21 | N=1 | O=4 }} }}

'''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.<ref>{{Cite journal|last1=Hagel|first1=Jillian M|last2=Morris|first2=Jeremy S|last3=Lee|first3=Eun-Jeong|last4=Desgagne-Penx|first4=Isabel|last5=Bross|first5=Crystal D|last6=Chang|first6=Limei|last7=Chen|first7=Xue|last8=Farrow|first8=Scott C|last9=Zhang|first9=Ye|date=2015|title=Transcriptome analysis of 20 taxonomically related benzylisoquinoline alkaloid-producing plants|url=http://openlib.tugraz.at/download.php?id=564f2fa60a35b&location=browse|journal=BMC Plant Biology|volume=15|pages=227|doi=10.1186/s12870-015-0596-0|pmid=26384972|pmc=4575454|doi-access=free}}</ref> It is found in many plants, including opium poppy,<ref name="transformation-Frick">{{cite journal |author1=Frick S |author2=Chitty JA |author3=Kramell R |author4=Schmidt J |author5=Allen RS |author6=Larkin PJ |author7=Kutchan TM | title=Transformation of opium poppy (''Papaver somniferum L.'') with antisense berberine bridge enzyme gene (anti-bbe) via somatic embryogenesis results in an altered ratio of alkaloids in latex but not in roots | journal=Transgenic Res. | year=2004 | pages=607&ndash;613 | volume=13 | issue=6 | pmid=15672841 | doi=10.1007/s11248-004-2892-6|s2cid=38780571 }}</ref> ''Croton flavens'',<ref name="alkaloids-from-croton-Eisenreich">{{cite journal |author1=Eisenreich WJ |author2=Hofner G |author3=Bracher F | title=Alkaloids from ''Croton flavens L.'' and their affinities to GABA-receptors | journal=Nat Prod Res | year=2003 | pages=437&ndash;440 | volume=17 | issue=6 | pmid=14577695 | doi=10.1080/1478641031000111516|s2cid=13192928 }}</ref> and certain plants in the genus ''Erythrina''.<ref name="studies-on-the-alkaloids-Ito">{{cite journal | author=Ito K | title=Studies on the alkaloids of ''Erythrina'' plants | journal= Yakugaku Zasshi | year=1999 | pages=340&ndash;356 | volume=119 | issue=5 | doi=10.1248/yakushi1947.119.5_340 | pmid=10375996| doi-access=free }}</ref>

Studies show that scoulerine is an antagonist ''in vitro'' at the α<sub>2</sub>-adrenoceptor, α<sub>1D</sub>-adrenoceptor and 5-HT receptor.<ref name="pharmacological-activity-Ko">{{cite journal |author1=Ko FN |author2=Yu SM |author3=Su MJ |author4=Wu YC |author5=Teng CM | title=Pharmacological activity of (−)-discretamine, a novel vascular α-adrenoceptor and 5-hydroxytryptamine receptor antagonist, isolated from ''Fissistigma glaucescens'' | journal=Br J Pharmacol | year=1993 | pages=882&ndash;888 | volume=110 | issue=2 | pmid=7902181 | pmc=2175899 | doi=10.1111/j.1476-5381.1993.tb13895.x}}</ref><ref name="discretamine-Ko">{{cite journal |author1=Ko FN |author2=Guh JH |author3=Yu SM |author4=Hou YS |author5=Wu YC |author6=Teng CM | title=(−)-Discretamine, a selective α<sub>1D</sub>-adrenoceptor antagonist, isolated from ''Fissistigma glaucescens'' | journal=Br J Pharmacol | year=1994 | pages=1174&ndash;1180 | volume=112 | issue=4 | pmid=7952879 | pmc=1910235 | doi=10.1111/j.1476-5381.1994.tb13207.x}}</ref> It has also been found to be a GABA<sub>A</sub> receptor agonist ''in vitro''.<ref name="alkaloids-from-croton-Eisenreich"/><ref name="positive-Halbsguth">{{cite journal |author1=Halbsguth C |author2=Meissner O |author3=Haberlein H | title=Positive cooperation of protoberberine type 2 alkaloids from ''Corydalis cava'' on the GABA(A) binding site | journal=Planta Med. | year=2003 | pages=305&ndash;309 | volume=69 | issue=4 | pmid=12709895 | doi=10.1055/s-2003-38869|s2cid=260282359 }}</ref>

==Biosynthesis== Scoulerine is produced by action of the enzyme reticuline oxidase, which uses oxygen to convert the N-methyl group of (''S'')-reticuline into a so-called "berberine bridge".<ref>{{cite journal | vauthors = Steffens P, Nagakura N, Zenk MH | date = 1984 | title = The berberine bridge forming enzyme in tetrahydroprotoberberine biosynthesis | journal = Tetrahedron Lett. | volume = 25 | issue = 9 | pages = 951&ndash;952 | doi = 10.1016/S0040-4039(01)80070-8 }}</ref><ref>{{cite journal | vauthors = Dittrich H, Kutchan TM | date = 1991 | title = Molecular cloning, expression, and induction of berberine bridge enzyme, an enzyme essential to the formation of benzophenanthridine alkaloids in the response of plants to pathogenic attack | journal = Proc. Natl. Acad. Sci. U.S.A. | volume = 88 | pages = 9969&ndash;73 | pmid = 1946465 | doi = 10.1073/pnas.88.22.9969 | issue = 22 | pmc = 52848 | bibcode = 1991PNAS...88.9969D | doi-access = free }}</ref><ref>{{cite journal | vauthors = Kutchan TM, Dittrich H | date = 1995 | title = Characterization and mechanism of the berberine bridge enzyme, a covalently flavinylated oxidase of benzophenanthridine alkaloid biosynthesis in plants | journal = J. Biol. Chem. | volume = 270 | pages = 24475&ndash;81 | pmid = 7592663 | doi = 10.1074/jbc.270.41.24475 | issue = 41 | doi-access = free }}</ref>

{{chemrxn|width=55%| {{chemrxn/cpd|qid=Q6122828|caption=(''S'')-reticuline }} {{chemrxn/arw||fwd_in={{chem2|O2}}|fwd_out={{chem2|2 H2O}} }} {{chemrxn/cpd|scoulerine }} }}

==References== {{reflist}}

Category:Isoquinolinoisoquinolines Category:Natural opium alkaloids Category:Hydroxyarenes Category:Catechol ethers Category:Methoxy compounds