Two New 11-Hydroxy-Substituted Gelsedine-Type Indole Alkaloids from the Stems of Gelsemium elegans
✍ Scribed by Bin-Feng Zhang; Gui-Xin Chou; Zheng-Tao Wang
- Publisher
- John Wiley and Sons
- Year
- 2009
- Tongue
- German
- Weight
- 239 KB
- Volume
- 92
- Category
- Article
- ISSN
- 0018-019X
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✦ Synopsis
Two new 11-hydroxy-substituted gelsedine-type indole alkaloids, named 11,14-dihydroxygelsenicine (1) and 11-hydroxygelsenicine (2), together with six known alkaloids, i.e., koumine, gelsemine, 14hydroxygelsenicine, 11-hydroxyhumantenine, gelsenicine, and (19Z)-akuammidine, were isolated from the EtOH extract of the stems of Gelsemium elegans Benth. Their structures were determined mainly by means of spectroscopic analyses including HR-ESI-MS and 2D-NMR (HSQC, HMBC, 1 H, 1 H-COSY). The configuration of 1 was confirmed by X-ray-diffraction analysis.
Introduction. -Gelsemium (Loganiaceae) is a small genus of three species, G. elegans (Gardn. & Champ.) Benth., G. sempervirens (L.) Jaume St.-Hilaire, and G. rankinii Small. G. elegans is distributed in Southeast Asia, and the other two species are native to North America [1]. G. elegans, which is known as Gou-Wen or Duan-Chang-Cao in China, is very toxic and has been used traditionally for the treatment of pain, spasticity, and skin ulcers in Chinese folk medicine [2]. The genus Gelsemium is a rich source of indole alkaloids. Pharmacological investigations on the crude and purified alkaloids of this plant have demonstrated promising antitumor [3], analgesic, and anti-inflammatory activities [4]. Presently, more than seventy Gelsemium alkaloids are known, which are classified into six types: sarpagine, koumine, humantenine, gelsedine, gelsemine, and yohimbane. Of these, some gelsedine-type alkaloids showed potent cytotoxic activity against A431 epidermoid carcinoma cells [5].
In our present study, the two new 11-hydroxy-substituted gelsedine-type indole alkaloids, 1 and 2 (Fig. 1), together with six known indole alkaloids, i.e., koumine [6], gelsemine [7], 14-hydroxygelsenicine [8], 11-hydroxyhumantenine [9], gelsenicine [8], and (19Z)-akuammidine [8], were isolated from the stems of G. elegans.
Results and Discussion. -Compound 1 was obtained as colorless cubic crystals. The molecular formula was established to be C 19 H 22 N 2 O 5 from the HR-MS data (m/z 359.1602 (
The UV and NMR spectra exhibited the characteristic Nmethoxyoxindole chromophore. The 1 H-and 13 C-NMR spectral signals in the aromatic region indicated an ABX system (d(H) 7.71 (d, J ¼ 8.2, HÀC(9)); 6.98 (dd, J ¼ 8.2, 2.2, HÀC(10)); 6.89 (d, J ¼ 2.2, HÀC(12))), suggesting the C(11) position being