Glycomaurin and Glycomaurrol, New Carbazole Alkaloids From Glycosmis mauritiana (Rutaceae) Bark

Kumar, V. Rajesh; Reisch, J.; Wickramasinghe, Anura

doi:10.1071/ch9891375

Cited by 39 publications

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“…The base peak at m/z 609 [MϪC 6 H 11 ] ϩ was due to the loss of a methylpentenyl group by a cleavage between C-1Ј and C-3. There was also another significant peak at m/z 263 which could be a doubly charged ion due to loss of two methylpentenyl groups [MϪ(2ϫC 6 In the absence of other reports on the CD of the known naturally-occurring biscarbazole alkaloids, it is difficult to draw definite conclusions from the curve concerning the absolute stereochemistry of the alkaloid, except to say that the magnitudes of the Cotton effects probably indicate the presence of one predominant atropo-enantiomer.…”

Section: C-mentioning

confidence: 94%

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mentioning

confidence: 99%

“…1,2) Carbazole alkaloids were isolated from the seeds 3) and the roots 4,5) of G. pentaphylla, from the bark of G. mauritiana 6) and G. rupestris, 7) and from the roots of G. arborea. 8) Carbazole alkaloids have also been found in other Rutaceous genera, e.g., Micromelum, Murraya, and Clausena.…”

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A New Dimeric Carbazole Alkaloid from Glycosmis stenocarpa Roots

Cuong

Hung

Sung

et al. 2004

CHEMICAL & PHARMACEUTICAL BULLETIN

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The genus Glycosmis, family Rutaceae, is a rich source of alkaloids, including those of the quinolone, quinazoline, furoquinoline, acridone, sulphur-containing amides and carbazole types.1,2) Carbazole alkaloids were isolated from the seeds 3) and the roots 4,5) of G. pentaphylla, from the bark of G. mauritiana 6) and G. rupestris, 7) and from the roots of G. arborea. 8) Carbazole alkaloids have also been found in other Rutaceous genera, e.g., Micromelum, Murraya, and Clausena. From two genera, Murraya and Clausena, nearly four fifths of the natural carbazole alkaloids have been isolated.9,10) In a continuing search for bioactive natural products from Vietnamese plants, a number of plants, including species Glycosmis stenocarpa (DRAKE) TAN., have been screened for cytotoxic, antifungal, and antibacterial activities.11,12) G. stenocarpa, local name "com ruou trai hep," is a small shrub, 0.75-1 m high. It is an endemic plant, found in some provinces in north Vietnam.13) This paper reports the isolation and structural elucidation of a new dimeric pyranocarbazole alkaloid, named bisisomahanine (1), and two known monomeric carbazole alkaloids, viz. murrayafoline-A (2) 14) and murrayanine (3), 15) from the roots of G. stenocarpa. Results and DiscussionBisisomahanine (1) was obtained as a pale ivory powder, mp 130-140°C, [a] D 20 Ϫ13.1°. The UV spectrum showed the typical absorbances at 209, 224, and 245 nm, closely similar to those of 2 and 3, and indicative of the carbazole skeleton in 1. Furthermore, it exhibited absorbances at 298 (sharp, strong) and 335 nm (broad, weak), typical of an angular pyranocarbazole unit as described for isomahanine (4). (Table 1) and the peak at m/z 83 in the EI-MS spectrum were assignable to the isohexenyl side chain.16,17) The assignments of carbons at positions C-1Ј and C-2Ј of alkaloid 1 are different than those reported for isomahanine (4), 16) and were confirmed by data from HMQC and HMBC experiments ( Table 1). The HMQC spectrum of 1 showed the direct .1 (C-3Ј), and 22.7 (C-2Ј). The 1 H-1 H COSY and NOESY spectra of 1 also confirmed the above assignment of the isohexenyl side chain (Fig. 1).In the downfield region of the 1 H-NMR spectrum, two broad singlets at d 7.51 and 5.14 were assigned to an NH and a phenolic hydroxyl group, respectively; this was supported by the IR bands at 3470 and 3362 cm Ϫ1, and the fact that no carbons were attached to these proton signals, as shown by the HMQC spectrum. There were two isolated pairs of orthocoupled protons: the first pair at d 6.73 (H-5) and 7.71 (H-6), and the second at d 6.43 (H-1) and 5.54 (H-2). The COSY spectrum confirmed the two separate spin systems. The NMR spectral data of the latter pair were similar to those in some Murraya alkaloids such as isomahanine (4) and mahanine (5), 16) murrayamine C (7), 18) and pyrayafoline-D (6) (assigned the same structure as 4 by Ito et al.), 17) indicating the presence of a pyran ring double bond in the pyranocarbazoletype skeleton of 1.The position of fusion between the pyrano and carbazole ...

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A New Dimeric Carbazole Alkaloid from Glycosmis stenocarpa Roots

Cuong

Hung

Sung

et al. 2004

CHEMICAL & PHARMACEUTICAL BULLETIN

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“…22) Therefore, the condensation of a hydroxycarbazole with 3-methylbut-2-enal in presence of a Lewis acid catalyst described here, appears as the first efficient method giving a facile access to the pyrano[3,2-b]carbazole series.…”

Section: Resultsmentioning

confidence: 99%

“…Nevertheless, the difficulties encountered in both terms of yield and separation of isomers in the course of the preparation of 21 from 1,4,9-trimethylcarbazole severely limited the practical scope of syntheses using N-methycarbazoles as starting materials. In contrast, N-methylation of a preformed pyranocarbazole gave excellent results, illustrated by the obtainment in 89% yield of 9-methoxy-2,2,5,6,11-pentamethyl-2,6-dihydropyrano [3,2-b]carbazole (22), when 12 was treated by methyl iodide and sodium hydride in dimethylformamide (Chart 3).…”

Section: Synthesis and Cytotoxic Activity Of Pyranocarbazole Analoguementioning

confidence: 99%

Synthesis and Cytotoxic Activity of Pyranocarbazole Analogues of Ellipticine and Acronycine

Tran-Thi¹,

Nguyen-Thi²,

Michel³

et al. 2004

CHEMICAL & PHARMACEUTICAL BULLETIN

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Natural products including a carbazole basic skeleton fused with another heterocyclic system currently receive a strong attention, due to the promising antitumor properties of several of their representatives.1) Of particular interest in this field are the pyrido [4,3-b]carbazole alkaloids and the indolo[2,3-a]carbazole antibiotics. The first series, illustrated by ellipticine (1) and 9-methoxyellipticine (2), both isolated from Ochrosia species (Apocynaceae) include compounds which act by intercalation within the DNA-double strand, followed by inhibition of topoisomerase II.2) A derivative of ellipticine, elliptinium (3), has been commercialized for the treatment of metastatic breast cancer.3) Rebeccamycine (4), isolated from Saccharothrix aerocolonigenes, is a typical representative of the second series currently under clinical trials. It induces topoisomerase I mediated DNA-cleavage. 4)The antitumor activity of several related indolocarbazoles has been recently discussed. 5)The structurally related pyrano[2,3-c]acridone alkaloid acronycine (5) isolated from Achronycia baueri SCHOTT. (Rutaceae) was shown to exhibit antitumor properties against a broad spectrum of solid tumor models.6-8) Nevertheless, its moderate potency and low water solubility rapidly appeared as severe drawbacks for a possible introduction into the clinic. A hypothesis of bioactivation of the 1,2-double bond of the chromene ring system of acronycine into the corresponding epoxide 9) led to the development of several series of more active structural analogues. The most significant improvements were obtained with diesters of 1,2-dihydroxy-1,2-dihydroacronycine 10) and, more recently, of 1,2-dihy-11) Representatives of this latter series, such as diacetate 6, are considered as valuable candidates for clinical studies.12) The mechanism of their action implies alkylation of the 2-amino group of DNA guanine residues by the ester leaving group at position 1 of the drug. 13,14) We describe here the synthesis and cytotoxic properties of various 2,2,5,11-tetramethyl-and 2,2,5,6,11-pentamethyl-2,6-dihydropyrano[3,2-b]carbazole derivatives. Such compounds associate the 1,4-dimethylcarbazole tricyclic system responsible for the intercalating properties of ellipticine related drugs, with the dimethylpyran pharmacophore of acronycine derivatives. ChemistryFor the synthesis of 2,2,5,11-tetramethyl-2,6-dihydropyrano[3,2-b]carbazole (7), the readily available 1,4-dimethyl-9H-carbazole-3-carbaldehyde (8), previously used as key-intermediate in several ellipticine syntheses, 15) was chosen as starting material. It was first oxidized by use hydrogen peroxide in acidic medium, into the corresponding 1,4-dimethyl-9H-carbazol-3-ol (9), according to the Matsumoto's procedure which has been applied by Langendoen et al. to the synthesis of related hydroxycarbazoles.16) Construction of the fused dimethylpyran ring was ensured by condensation of 9 Various 2,2,5,11-tetramethyl-and 2,2,5,6,11-pentamethyl-2,6-dihydropyrano[3,2-b]carbazole derivatives were synthesized by c...

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Synthesis of Alkaloids by Transition Metal‐mediated Oxidative Cyclization

Knölker

2007

Modern Alkaloids

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Glycomaurin and Glycomaurrol, New Carbazole Alkaloids From Glycosmis mauritiana (Rutaceae) Bark

Cited by 39 publications

References 0 publications

A New Dimeric Carbazole Alkaloid from Glycosmis stenocarpa Roots

A New Dimeric Carbazole Alkaloid from Glycosmis stenocarpa Roots

Synthesis and Cytotoxic Activity of Pyranocarbazole Analogues of Ellipticine and Acronycine

Synthesis of Alkaloids by Transition Metal‐mediated Oxidative Cyclization

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