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Taburnaemines A-I, Cytotoxic Vobasinyl-Iboga-Type Bisindole Alkaloids from Tabernaemontana corymbosa.

ABSTRACT: Nineteen vobasinyl-ibogan-type bisindole alkaloids, including nine new compounds, taburnaemines A-I (1-9), were isolated from the twigs and leaves of Tabernaemontana corymbosa. The structures and absolute configurations of the new alkaloids were determined by a combination of MS, NMR, and ECD analyses. Alkaloids 1-5 contain a rare 1,3-oxazinane moiety in the vobasinyl unit, while 6 has an uncommon 1,3-oxazolidine moiety in the iboga unit. The absolute configurations of alkaloid 1 and the known alkaloid tabernaecorymbosine A (10) were confirmed by single-crystal X-ray diffraction analysis. All of the bisindole alkaloids, except 2 and 16'-decarbomethoxytabernaecorymbosine A (14), showed antiproliferative activity (IC50 2.6-9.8 ?M) against several human cancer cell lines, including A-549, MDA-MB-231, MCF-7, KB, and P-glycoprotein-overexpressing multidrug-resistant KB cells. The preliminary structure-activity relationship correlations are also discussed.

SUBMITTER: Zhang Y

PROVIDER: S-EPMC7446768 | biostudies-literature | 2018 Mar

REPOSITORIES: biostudies-literature

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Taburnaemines A-I, Cytotoxic Vobasinyl-Iboga-Type Bisindole Alkaloids from Tabernaemontana corymbosa.

Zhang Yu Y Yuan Yu-Xi YX Goto Masuo M Guo Ling-Li LL Li Xiao-Nian XN Morris-Natschke Susan L SL Lee Kuo-Hsiung KH Hao Xiao-Jiang XJ

Journal of natural products 20180110 3

Nineteen vobasinyl-ibogan-type bisindole alkaloids, including nine new compounds, taburnaemines A-I (1-9), were isolated from the twigs and leaves of Tabernaemontana corymbosa. The structures and absolute configurations of the new alkaloids were determined by a combination of MS, NMR, and ECD analyses. Alkaloids 1-5 contain a rare 1,3-oxazinane moiety in the vobasinyl unit, while 6 has an uncommon 1,3-oxazolidine moiety in the iboga unit. The absolute configurations of alkaloid 1 and the known a ...[more]

PMID: 29319316

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Project description:ObjectiveThe iboga alkaloids are a class of small molecules defined structurally on the basis of a common ibogamine skeleton, some of which modify opioid withdrawal and drug self-administration in humans and preclinical models. These compounds may represent an innovative approach to neurobiological investigation and development of addiction pharmacotherapy. In particular, the use of the prototypic iboga alkaloid ibogaine for opioid detoxification in humans raises the question of whether its effect is mediated by an opioid agonist action, or if it represents alternative and possibly novel mechanism of action. The aim of this study was to independently replicate and extend evidence regarding the activation of ?-opioid receptor (MOR)-related G proteins by iboga alkaloids.MethodsIbogaine, its major metabolite noribogaine, and 18-methoxycoronaridine (18-MC), a synthetic congener, were evaluated by agonist-stimulated guanosine-5´-O-(?-thio)-triphosphate ([(35)S]GTP?S) binding in cells overexpressing the recombinant MOR, in rat thalamic membranes, and autoradiography in rat brain slices.Results and significanceIn rat thalamic membranes ibogaine, noribogaine and 18-MC were MOR antagonists with functional Ke values ranging from 3 uM (ibogaine) to 13 uM (noribogaine and 18MC). Noribogaine and 18-MC did not stimulate [(35)S]GTP?S binding in Chinese hamster ovary cells expressing human or rat MORs, and had only limited partial agonist effects in human embryonic kidney cells expressing mouse MORs. Ibogaine did not did not stimulate [(35)S]GTP?S binding in any MOR expressing cells. Noribogaine did not stimulate [(35)S]GTP?S binding in brain slices using autoradiography. An MOR agonist action does not appear to account for the effect of these iboga alkaloids on opioid withdrawal. Taken together with existing evidence that their mechanism of action also differs from that of other non-opioids with clinical effects on opioid tolerance and withdrawal, these findings suggest a novel mechanism of action, and further justify the search for alternative targets of iboga alkaloids.

Dataset Information

Taburnaemines A-I, Cytotoxic Vobasinyl-Iboga-Type Bisindole Alkaloids from Tabernaemontana corymbosa.

Publications

Taburnaemines A-I, Cytotoxic Vobasinyl-Iboga-Type Bisindole Alkaloids from Tabernaemontana corymbosa.

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