• 1 †School of Pharmacy, University of Nottingham Malaysia Campus, Jalan Broga, 43500 Semenyih, Selangor, Malaysia
  • 2 ‡School of Pharmacy, Centre for Biomolecular Sciences, The University of Nottingham, University Park, Nottingham, Nottinghamshire NG72RD, U.K
  • 3 §Department of Chemistry, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia
J Nat Prod, 2015 May 22;78(5):1129-38.
PMID: 25919190 DOI: 10.1021/acs.jnatprod.5b00117


Six new indole alkaloids, viz., cononusine (1, a rare example of an iboga-pyrrolidone conjugate), ervaluteine (2), vincamajicine (3), tacamonidine (4), 6-oxoibogaine (5), and N(4)-chloromethylnorfluorocurarine chloride (6), and two new vobasinyl-iboga bisindole alkaloids, ervatensines A (7) and B (8), in addition to other known alkaloids, were isolated from the stem-bark extract of the Malayan Tabernaemontana corymbosa. The structures of these alkaloids were established on the basis of NMR and MS analyses and, in one instance (7), confirmed by X-ray diffraction analysis. Vincamajicine (3) showed appreciable activity in reversing multidrug resistance in vincristine-resistant KB cells (IC50 2.62 μM), while ervatensines A (7) and B (8) and two other known bisindoles displayed pronounced in vitro growth inhibitory activity against human KB cells (IC50 < 2 μM). Compounds 7 and 8 also showed good growth inhibitory activity against A549, MCF-7, MDA-468, HCT-116, and HT-29 cells (IC50 0.70-4.19 μM). Cell cycle and annexin V-FITC apoptosis assays indicated that compounds 7 and 8 inhibited proliferation of HCT-116 and MDA-468 cells, evoking apoptotic and necrotic cell death.

* Title and MeSH Headings from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.