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Please use this identifier to cite or link to this item: http://hdl.handle.net/1812/519

Title: Biologically active Indole and Bisindole alkaloids from Kopsia and Tabernaemontana
Authors: Lim, Kuan Hon
Keywords: Active Indole
Kopsia arborea
Kopsia tenuis
Tabernaemontana corymbosa
Bisindole alkaloid
Issue Date: 2008
Publisher: University Malaya
Abstract: Three Malaysian plants viz., Kopsia arborea, Kopsia tenuis, and Tabernaemontana corymbosa were investigated for their alkaloidal content and the results are summarized below (Table). A total of 111 alkaloids were isolated and characterized from these three plants. Of these, 52 are new alkaloids. Kopsia arborea yielded a total of 25 new alkaloids, of which six, viz., the three-nitrogen pentacyclic indole arboflorine (1), the heptacyclic cage indole arbophylline (2), the regioisomeric indoles, arboricine (3) and arboricinine (4), the tetracyclic indole mersicarpine (11), and the seco-leuconoxine alkaloid, arboloscine (12), are notable for incorporating novel or intriguing molecular skeletons. Kopsia tenuis provided a new lundurine alkaloid, lundurine D (66) (in addition to the previously reported lundurines A–C, 63–65) and tenuisines A−C (67−69). The structures of tenuisines A–C (67–69) were revised from a dimeric to a monomeric structure based on new LSIMS data. The stem-bark and leaf extracts of Tabernaemontana corymbosa gave a total of 26 new alkaloids. Of these, conolutinine (70) represents an unprecedented hexacyclic indole alkaloid incorporating a diazaspiro center as well as fused oxadiazepine-tetrahydrofuran rings, while conoliferine (72) and conomicidines A and B (73 and 74) represent the first examples of indole alkaloids attached to lignan or p-hydroxycinnamyl moieties. Other new alkaloids from T. corymbosa are variations of the Aspidosperma, iboga, corynanthe, ajmaline, and tacaman alkaloids. A biomimetic transformation of pericine (26) to valparicine (24) and apparicine (424), and from jerantinines A (86) and E (90) to the corresponding vincamine derivatives were carried out. Valparicine (24), jerantinines A–E (86–90), and the four iboga-vobasinyl bisindoles, 105−108, showed pronounced cytotoxicity toward KB cells (IC50 0.1−3.6 μg/mL), while lundurines B (64) and D (66) showed appreciable cytotoxicity toward B16 melanoma cells (IC50 2.8 and 7.2 μg/mL, respectively). The ajmaline-type alkaloid, 17-dehydrovincamajine (100), showed strong activity in reversing MDR in vincristine-resistant KB cells (IC50 0.92 μg/mL), while arboricine (3),arboricinine (4), 19(S)-methoxytubotaiwine (19), 19(R)- ethoxytubotaiwine (20), lundurine B (64), lundurine D (66), and lirofoline A (71) showed only moderate activity (IC50 3−10 μg/mL).
Description: Thesis (PhD) -- Faculty of Science, University of Malaya, 2009.
URI: http://dspace.fsktm.um.edu.my/handle/1812/519
Appears in Collections:PhD Theses : Science

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