Carbazole Alkaloids from the Stems of Clausena lansium

Abstract

Ten new carbazole alkaloids, claulansines A−J (1−10), and seven known analogues (11−17) were isolated from the stems of Clausena lansium. Their structures were established on the basis of extensive spectroscopic analyses, and their absolute configurations were determined by CD experiments and computational methods. Screening results indicated that compounds 1, 6, 8−10, 13, 14, and 17 showed selective neuroprotective effects at the concentration of 10 μM.

Clauemarazoles A–G, seven carbazole alkaloids from the stems of Clausena emarginata

“…Analyses of the NMR spectra indicated that 3 was also a 1-oxygenated 2,3-substituted carbazole alkaloid, similar to the known compound claulansine E [2].…”

“…The nineteen known carbazole alkaloids were identified to be mafaicheenamine C (6) [12], mafaicheenamine E (7) [13], claulansine G (8) [2], claulamine E (9) [14],…”

Alkaloids from the stems of Clausena lansium and their neuroprotective activity

“…The known compounds isolated were claulansine B (4b), 10 claulansine D (5b), 10 (À)-(1S,3S)-1-methyl-1,2,3,4-tetrahydro-b-carboline-3-carboxylic acid (6a), 28 (+)-(1R,3S)-1-methyl-1,2,3,4-tetrahydro-b-carboline-3-carboxylic acid (6b), 28 (R)-isoplatydesmine (7a), 29 (S)-isoplatydesmine (7b), 30 claulansine A (8), 10 ribalinine (9), 31 g-fagarine (10), 32 dictamnine (11), 33 N-(2-hydroxy-2-phenylethyl)-cinnamamide (12), 34 N-phenylethylbenzamide (13).…”

“…[2][3][4][5][6][7][8][9][10] The leaves and fruits of Clausena lansium, Clausena excavata, Clausena emarginata, and Clausena anisum-molens are not only eaten as food but also used for traditional medicine.…”

“…[12][13][14] Previously, twenty new natural products including thirteen new carbazole alkaloids, 10,15 eight alkaloid glycosides, 16 four new coumarins, 17 a new amide and a new megastigmane glucoside 18 from the leaves and skeels of C. lansium were reported by our research group, and some of these alkaloids showed selective neuroprotective effects. In order to investigate the potential neuroprotective constituents from different parts of C. lansium, n-BuOH extract of the stems of this plant were selected for investigation.…”