taxonID	type	description	language	source
1F3887EBFF80FFF8711E1019FC4452B8.taxon	description	The seeds (5.8 kg) of C. australe were extracted with 50 % aqueous EtOH. The chromatographic separation of the extract using various ion-exchange resins led to isolation of eleven alkaloids (1 – 3, 5, 6, 8 – 12, and 14). The 1 H NMR and 13 C NMR spectra of alkaloid 1 were in accord with those of 2 R - hydroxymethyl- 3 S - hydroxypyrolidine (CYB- 3), which has been isolated previously from the same plant C. australe (Nash et al., 1985; Kato et al., 2003). The biosynthesis of the bicyclic indolizidine and pyrrolizidine iminosugars has not been elucidated yet, but CYB- 3 (1), N - hydroxyethyl- 2 - hydroxymethyl- 3 - hydroxypyrrolidine, and N - methyl- trans - 4 - hydroxy-L- proline (Molyneux et al., 1991; Haraguchi et al., 2003) can be speculated as being important intermediate compounds because the distributions of these pyrrolidines and of castanospermine are closely related and appear to be restricted to a small taxonomic group. Alkaloids 2 and 3 were identified as fagomine and 3 - epi - fagomine, respectively, from an analysis of their 1 H NMR and 13 C NMR spectroscopic data. Fagomine (2) was first isolated from buckwheat seeds (Fagopyrum esculentum) (Koyama and Sakamura, 1974). We have previously reported that fagomine (2) and 3 - epi - fagomine (3) occur abundantly in the leaves and roots of Xanthocercis zambesiaca, from southern Africa (Kato et al., 1997). The 1 H and 13 C NMR spectroscopic data of alkaloids 5, 6, and 8 – 12 were in accord with those of the polyhydroxylated pyrrolizidines, australine, 1 - epi - australine, 2,3 - di epi - australine, 2,3,7 - tri epi - australine, and the polyhydroxylated indolizidines, castanospermine, castanospermine- 8 - O - b- D- glucoside, 6 - epi - castanospermine isolated earlier from C. australe (Molyneux et al., 1986, 1988; Kato et al., 2003). The 1 H NMR and 13 C NMR spectra of alkaloid 14 were in accord with those of 7 - deoxy- 6 - epi - castanospermine (Molyneux et al., 1990). Recently, this compound has been synthesized in ten steps from a common chiral building block (+) - tetramic acid derivative (Liu et al., 2010). The dried leaves (360 g) of C. australe were extracted with 50 % aqueous MeOH. The chromatographic separation of the extract using various ion-exchange resins led to isolation of nine alkaloids (1, 2, 4 – 7, 10, 12, and 13). Alkaloids 4 and 7 were identified as 3,4 - di epi - fagomine and 3 - epi - australine, respectively, from an analysis of their 1 H NMR and 13 C NMR spectroscopic data (Kato et al., 1997, 2003). The structural determination of the new alkaloid 13 is described below. Alkaloid 13 was determined to have the molecular formula C 8 H 15 NO 4 by HRFABMS. The 13 C NMR spectroscopic data of 6,8 - di epi - castanospermine were closely related to those of 6 - epi - castanospermine. In the 1 H NMR spectrum, the H- 1 showed similar coupling constants to H- 2 and H- 8 a as those of 6 - epi - castanospermine, indicating a common stereochemical configuration for H- 1 and H- 8 a. The stereo configurations of 6,8 - di epi - castanospermine were corroborated by definite NOEs between H- 7 and H- 8 a or H- 5 ax and by the presence of a W-path long-range coupling between H- 6 and H- 8. Hence, alkaloid 13 was shown to be 6,8 - di epi - castanospermine.	en	Kato, Atsushi, Hirokami, Yuki, Kinami, Kyoko, Tsuji, Yutaro, Miyawaki, Shota, Adachi, Isao, Hollinshead, Jackie, Nash, Robert J., Kiappes, J. L., Zitzmann, Nicole, Cha, Jin K., Molyneux, Russell J., Fleet, George W. J., Asano, Naoki (2015): Isolation and SAR studies of bicyclic iminosugars from Castanospermum australe as glycosidase inhibitors. Phytochemistry 111: 124-131, DOI: 10.1016/j.phytochem.2014.12.011, URL: http://dx.doi.org/10.1016/j.phytochem.2014.12.011
