Alkaloidal and other constituents from the root bark of Clausena excavata

Ten new carbazole alkaloids, clausine-M, -N, -O, -P, -Q, -R, -S, -U, -V and clausenatine-A, together with 39 known compounds were isolated and identif ied from the acetone extract of the root bark of Clausena excavata. Their s tructures have been elucidated by spectroscopic analyses. This is the first report of a decarboxylated carbazole alkaloid from a natural source. The p resence of a C-23-skeleton carbazole alkaloid in a plant of Clausena genus is also reported for the first time. (C) 1999 Elsevier Science Ltd. All rig hts reserved.