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Names | |
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IUPAC name 12-Methoxyibogamine-18-carboxylic acid, methyl ester | |
Systematic IUPAC name Methyl 17-ethyl-7-methoxy-3,13-diazapentacyclo[13.3.1.02,10.04,9.013,18] nonadeca-2(10),4,6,8-tetraene-1-carboxylate [1] | |
Other names Methyl 12-methoxyibogamine-18-carboxylate | |
Identifiers | |
3D model (JSmol) | |
ChEBI | |
ChEMBL | |
ChemSpider | |
ECHA InfoCard | 100.214.137 |
MeSH | Voacangine |
PubChem CID | |
UNII | |
CompTox Dashboard (EPA) | |
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Properties | |
C22H28N2O3 | |
Molar mass | 368.477 g·mol−1 |
Melting point | 136 to 137 °C (277 to 279 °F; 409 to 410 K) |
log P | 3.748 |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). |
Voacangine (12-methoxyibogamine-18-carboxylic acid methyl ester) is an alkaloid found predominantly in the root bark of the Voacanga africana tree, as well as in other plants such as Tabernanthe iboga , Tabernaemontana africana , Trachelospermum jasminoides , Tabernaemontana divaricata and Ervatamia yunnanensis . [2] [3] [4] [5] It is an iboga alkaloid which commonly serves as a precursor for the semi-synthesis of ibogaine. [6] It has been demonstrated in animals to have similar anti-addictive properties to ibogaine itself. [7] It also potentiates the effects of barbiturates. [8] Under UV-A and UV-B light its crystals fluoresce blue-green, and it is soluble in ethanol.
Voacangine exhibits AChE inhibitory activity. [9] [10] Docking simulation reveals that it has inhibitory effect on VEGF2 kinase [11] and reduces angiogenesis. [12] [13] Like ibogaine, its a potent HERG blocker in vitro. [14] It also acts as antagonist to TRPM8 and TRPV1 receptor, but agonist of TRPA1. [15] [16]
The absolute bioavailability of voacangine is around 11–13%. [14]
High doses of voacangine produce convulsions and asphyxia. [17]
The late-stage biosynthesis of (-)-voacangine in Tabernanthe iboga , a (-)-ibogamine-type alkaloid, has been elucidated via homology-guided transcriptome mining. [18] Suspected RNA transcripts involved in (-)-voacangine biosynthesis were identified via sequence homology to previously described enzymes comprising the (+)-catharanthine biosynthesis, [19] a (+)-ibogamine-type alkaloid from the taxonomically related plant Catharanthus roseus .
Ibogamine-type alkaloids are biosynthesized from the late stage intermediate stemmadenine acetate, a strictosidine-derived biosynthetic intermediate for a wide number of plant natural products. The biosynthesis of stemmadenine acetate has been characterized in C. roseus [19] but remains uncharacterized in T. iboga.
Conversion of stemmadenine acetate to (-)-voacangine in T. iboga involves five enzymes. First, stemmadenine acetate (1) is converted to precondylocarpine acetate (2) by one of three T. iboga precondylocarpine acetate synthases (TiPAS1/2/3), a flavin-dependent oxidase. Next, 2 is reduced to the enamine (3), dihydroprecondylocarpine acetate, by one of two NADPH-dependent T. iboga dihydroprecondylocarpine acetate synthase (TiDPAS1/2).
Up to this point, the biosynthetic path towards the (-)-ibogamine alkaloids and (+)-ibogamine alkaloids is identical. Stereochemical divergence occurs during the cyclization step, whereby T. iboga coronaridine synthase (TiCorS), a catharanthine synthase (CS) homologue, catalyzes a stereoselective formal Diels-Alder reaction on dehydrosecodine (4) to form coronaridine iminium (5). A proposed mechanism for dehydrosecodine formation from 3 involves iminium-formation/deacetylation, enamine-formation, and subsequent isomerization. Reduction of 5 to (-)-coronaridine (6) is proposed to be catalyzed by TiDPAS, although it is unclear if the reduction is actually enzymatic due to a lack of a reaction trial with only NADPH. [Note 1] After formation of 6, the substrate is then 10-hydroxylated by ibogamine 10-hydroxylase (I10H), a CYP450 enzyme, and subsequently 10-O-methylated by noribogaine-10-O-methyltransferase (N10OMT), a SAM dependent enzyme, [20] to form (-)-voacangine (7).