Tirucallane-Type Alkaloids from the Bark of Dysoxylum laxiracemosum

Abstract

Eight novel tirucallane-type alkaloids (1-8) and 11 known compounds were isolated from a methanol extract of the bark of Dysoxylum laxiracemosum. The structures of 1-8 were elucidated using extensive NMR spectrometric and mass spectroscopic methods. Compounds 1 and 5, named laxiracemosins A and E, showed significant cytotoxicity against five human cancer cell lines.

Spectroscopic characterizations, X-ray studies, and electronic circular dichroism calculations of two alkaloid triterpenoids

“…These data suggested the tetracyclic part of 1 to be a 3-ketone-D 7 (8) tirucallane tetranortriterpenoid [12,13].…”

“…Alkaloid triterpenoids are rarely encountered as natural products with only several examples isolated from Meliaceae [1,8], however, some of the structures were still ambiguous, especially in their absolute conformations. In this article, spectroscopic characterizations, X-ray studies and ECD calculations were used to make a definite study on the stereochemistry of the two alkaloid triterpenoids.…”

“…Earlier studies on this plant have disclosed the presence of sesquiterpenoids [5] and prieurianin-type limonoids [6,7]. In our search for bioactive substances from A. grandifolia, one C 26 tirucallane-type nortriterpenoid, laxiracemosin H (1) [8] containing maleimide moiety, and along with an alkaloid triterpenoid, laxiracemosin A (2) [8], with a skeleton featuring an isobutyl-substituted pyrrole ring, were isolated from the stem barks of A. grandifolia (Fig. 1).…”

Cytotoxic Activity of Inositol Angelates and Tirucallane-Type Alkaloids from Amoora Dasyclada

“…Some vegetative storage proteins in Meliaceae were investigated by Tian et al [3]. Amoora dasyclada, a member of the Meliaceae family, yields varied kinds of terpenoids, including diterpenoid, triterpenoid and tetraterpenoid, with anticancer and cytotoxic activities [4][5][6][7][8][9][10][11][12][13]. We firstly isolated three new inositol angelates and two alkaloids (compounds 1-5, Figure 1) which have not been investigated previously in Amoora dasyclada.…”

Cytotoxic Indole Alkaloid 3α-Acetonyltabersonine Induces Glioblastoma Apoptosis via Inhibition of DNA Damage Repair

“…Searching for optimized or simplified indole alkaloids has been the spotlight of antitumor drug discovery for several years. In our continual search for natural antitumor products from medicinal plants, indole alkaloids were found to be the most potent candidates in a cytotoxicity bioassay against five human cancer cell lines [10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29]. Among these cytotoxic indoles, 3 α -acetonyltabersonine, an aspidosperma-type monoterpenoid indole alkaloid, structurally similar to vindoline, showed the best bioactivity, with IC 50 values of 0.2–0.6 μM against human myeloid leukemia HL-60 cells, hepatocellular carcinoma SMMC-7721 cells, lung cancer A549 cells, breast cancer MCF-7 cells, and colon cancer SW480 cells.…”