Murraya siamensis

The known alkaloid heptaphylline has been isolated from the roots of Clausena harmandiana Pierre (Rutaceae) along with two new carbazole alkaloids identified as 2-hydroxy-3-formyl-7-methoxycarbazole (58) and 7-methoxyheptaphylline (59). The H- and l3C-NMR spectra have been analyzed and used to position the various functional groups (54,55). Other carbazole alkaloids isolated from the roots of Murraya siamensis Craib are identified as murrayanine, girinimbine, and mukonal, which occur together with heptaphylline and compounds 58 and 59 (56-55). Three new alkaloids have also been isolated from M. siamensis and named 3-formyl-2,7-dimethoxycarbazole (60), 3-formyl-2-methoxylcarbazole (O-methylmukonal) (61), and 7-methoxymurrayacine (62) (59). From the roots of Rauwolfia serpentina, the new alkaloid indobine (63) (60), the benzyl ester, and indobinine (64) (61), the cyclohexyl ester of indolepropionic acid, have been isolated and identified. 

Clauszoline-K and dausine C (clauszoline-L) have been isolated from the stem bark of the Chinese medidnal plant Clausena excavata [72], Clausine M and dausine N have been found in the root bark of the same plant [73]. The bioassay-guided fractionation of the organic extract of Murraya siamensis, collected in Thailand, led to the isolation of siamenol, which shows HIV-inhibitory activity [74], A simple route to these 7-oxygenated carbazole alkaloids has been developed, based on a highly efficient palladium-catalyzed approach (Scheme 15.21) [75] (Table 15.4). 

Ito, C. Itoigawa, M. Onoda, S. Hosokawa, A. Ruangrungsi, N. Okuda, T. Tokuda, H. Nishino, H. Furukawa, H. Chemical constituents of Murraya siamensis three coumarins and their anti-tumor promoting effect. Phytochemistry 2005, 66, 567-572. 

In 1966, Chakraborty et al. described the isolation of (+)-mahanimbine (139a) from M. koenigii (132). Two years later, Narasimhan et al. corrected the structural assignment of Chakraborty. Although alkaloid 139a was obtained in optically active form ([a]o +52), the absolute configuration is still unknown (111,133). Later, the racemic alkaloid, (+ )-mahanimbine (139b), was isolated independently from two different Murraya species, M. euchrestifolia (29) and M. siamensis (85). 

A series of 7-oxygenated carbazole alkaloids has been synthesized by us for the first time, including clauszoline-K (117), 3-formyl-7-hydroxycarbazole (119), clau-sine M (120), clausine N (121), and siamenol (124) [148]. Clauszoline-K (117) and clauszoline-L (118) have been isolated by Ito et al. from the stem bark of C. excavata [115]. Wu and co-workers had isolated the same compound 118 one year earlier from the same source and named it clausine C (118) [158]. 3-Formyl-7-hydroxycarbazole (119) was obtained from the root bark of Murraya euchrestifolia [159]. Clausine M (120) and clausine N (121) were isolated from the root bark of C. excavata by Wu et al. [116]. Siamenol (124) was isolated from an extract of M. siamensis and proved to have anti-HIV activity [160]. 

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