{{Chembox | ImageFile = Tabersonine.svg | ImageClass = skin-invert-image | ImageSize = 200px | IUPACName = Methyl 2,3,6,7-tetradehydro-5α,12β,19α-aspidospermidine-3-carboxylate | SystematicName = Methyl (3a''R'',3a<sup>1</sup>''S'',10b''R'')-3a-ethyl-3a,3a<sup>1</sup>,4,6,11,12-hexahydro-1''H''-indolizino[8,1-''cd'']carbazole-5-carboxylate | OtherNames = |Section1={{Chembox Identifiers | CASNo = 4429-63-4 | UNII_Ref = {{fdacite|correct|FDA}} | UNII = MN955K48NB | CASNo_Ref = {{cascite|correct|CAS}} | CASNo1 = 29479-00-3 | CASNo1_Ref = {{cascite|correct|CAS}} | CASNo1_Comment = (''hydrochloride'') | KEGG = C09244 | PubChem = 20485 | ChemSpiderID = 19292 | SMILES = CC[C@]12CC(=C3[C@@]4([C@H]1N(CC4)CC=C2)c5ccccc5N3)C(=O)OC | StdInChI = 1S/C21H24N2O2/c1-3-20-9-6-11-23-12-10-21(19(20)23)15-7-4-5-8-16(15)22-17(21)14(13-20)18(24)25-2/h4-9,19,22H,3,10-13H2,1-2H3/t19-,20-,21-/m0/s1 | StdInChIKey = FNGGIPWAZSFKCN-ACRUOGEOSA-N }} |Section2={{Chembox Properties | C=21 | H=24 | N=2 | O=2 | Appearance = | Density = | MeltingPt = | BoilingPt = | Solubility = }} |Section3={{Chembox Hazards | MainHazards = | FlashPt = | AutoignitionPt = }} }}
'''Tabersonine''' is a terpene indole alkaloid found in the medicinal plant ''Catharanthus roseus'' and also plants in the genus ''Voacanga''<ref>{{cite journal | last1 = Van Beek | first1 = T.A. | last2 = Verpoorte | first2 = R. | last3 = Svendsen | first3 = A.Baerheim | last4 = Leeuwenberg | first4 = A.J.M. | last5 = Bisset | first5 = N.G. | title = Tabernaemontana L. (Apocynaceae): A review of its taxonomy, phytochemistry, ethnobotany and pharmacology | journal = Journal of Ethnopharmacology | date = 1984 | volume = 10 | issue = 1 | pages = 1–156 | doi = 10.1016/0378-8741(84)90046-1 | pmid = 6371388 }}</ref>{{rp|8}} (both taxa belonging to the alkaloid-rich family Apocynaceae). Tabersonine is hydroxylated at the 16 position by the enzyme tabersonine 16-hydroxylase to form 16-hydroxytabersonine.<ref>{{cite journal | last1 = St-Pierre | first1 = B. | last2 = De Luca | first2 = V. | title = A Cytochrome P-450 Monooxygenase Catalyzes the First Step in the Conversion of Tabersonine to Vindoline in Catharanthus roseus | journal = Plant Physiology | date = 1995 | volume = 109 | issue = 1 | pages = 131–139 | doi = 10.1104/pp.109.1.131 | pmid = 12228585 | pmc = 157569 }}</ref> Tabersonine is the first intermediate leading to the formation of vindoline one of the two precursors required for vinblastine biosynthesis.
==Biosynthesis== Tabersonine is an indole alkaloid whose immediate precursor in ''Catharanthus roseus'' (Madagascar periwinkle) is the compound dehydrosecodine. This is cyclised by the enzyme tabersonine synthase:<ref>{{cite journal |last1=Caputi |first1=Lorenzo |last2=Franke |first2=Jakob |last3=Farrow |first3=Scott C. |last4=Chung |first4=Khoa |last5=Payne |first5=Richard M. E. |last6=Nguyen |first6=Trinh-Don |last7=Dang |first7=Thu-Thuy T. |last8=Soares Teto Carqueijeiro |first8=Inês |last9=Koudounas |first9=Konstantinos |last10=Dugé De Bernonville |first10=Thomas |last11=Ameyaw |first11=Belinda |last12=Jones |first12=D. Marc |last13=Vieira |first13=Ivo Jose Curcino |last14=Courdavault |first14=Vincent |last15=o'Connor |first15=Sarah E. |display-authors=3 |title=Missing enzymes in the biosynthesis of the anticancer drug vinblastine in Madagascar periwinkle |journal=Science |date=2018 |volume=360 |issue=6394 |pages=1235–1239 |doi=10.1126/science.aat4100 |pmid=29724909 }}</ref><ref name=Demars2024>{{cite journal |last1=Demars |first1=Matthew D. |last2=o'Connor |first2=Sarah E. |title=Evolution and diversification of carboxylesterase-like [4+2] cyclases in aspidosperma and iboga alkaloid biosynthesis |journal=Proceedings of the National Academy of Sciences |date=2024 |volume=121 |issue=7 |article-number=e2318586121 |doi=10.1073/pnas.2318586121 |doi-access=free |pmid=38319969 }}</ref>
{{chemrxn|width=55%| {{chemrxn/cpd|dehydrosecodine }} {{chemrxn/arw|uppercaption=Synthase }} {{chemrxn/cpd|tabersonine }} }}
The biosynthetic pathway to vindoline and vinblastine continues when tabersonine is hydroxylated by the enzyme tabersonine 16-hydroxylase, giving 16-hydroxytabersonine:<ref name=Demars2024/>
{{chemrxn|width=55%| {{chemrxn/cpd|tabersonine }} {{chemrxn/arw|fwd_in={{chem2|O2}}|fwd_out={{chem2|2 H2O}} }} {{chemrxn/cpd|16-Hydroxytabersonine|caption=16-hydroxytabersonine }} }}
== See also == *Conopharyngine *Tabernanthine
==References== {{Reflist}}
Category:Indole alkaloids Category:Indolizinoindoles Category:Methyl esters