Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/23/2003
Publication Date: 8/6/2003
Citation: Haraguchi, M., Gorniak, S.L., Ikeda, K., Minami, Y., Kato, A., Watson, A.A., Nash, R.J., Molyneux, R.J., Asano, N. 2003. Alkaloidal components in the poisonous plant, ipomoea carnea (convolvulaceae). Journal of Agricultural and Food Chemistry. 51(17):4995-5000. Interpretive Summary: Seven compounds have been identified in the leaves, flowers and seeds of a plant related to sweet potatoes, responsible for poisoning of goats in Brazil. Two of these compounds were previously shown to be responsible for the toxicity of locoweeds to livestock and are present at similar levels to that of the locoweeds. The biological properties of all of these compounds were similar, affecting the way in which sugars are involved in the basic properties of living cells. The effects on goats were similar to those of locoweeds but with some minor differences in symptoms, perhaps caused by the additional compounds. These results provide important information to livestock producers as to plants that livestock should be prevented from eating.
Technical Abstract: Natural intoxication of livestock by the ingestion of Ipomoea carnea (Convolvulaceae) sometimes occurs in the tropical region of the world. Polyhydroxylated alkaloids were isolated from the leaves, flowers, and seeds of the poisonous plant, and characterized. Chromatographic separation of the leaf extract resulted in the isolation of swainsonine (1), 2-epi-lentiginosine (2), calystegines B1 (3), B2 (4), B3 (5), and C1 (6), and N-methyl-trans-4-hydroxy-L-proline (7). The contents of 1 in the fresh leaves and flowers were 0.0029 and 0.0028%, respectively, whereas the contents of 1, 3, and 4 in the seeds were about 10 times higher than those in the leaves and flowers. Alkaloids 3, 4, and 6 showed a potent inhibitory activity toward rat lysosomal _eta-glucosidase, with IC50 values of 2.1, 0.75, and 0.84 micromolar, respectively, and alkaloid 5 was a moderate inhibitor of _lpha- and _eta-mannosidases. Although alkaloid 1 is known as a powerful inhibitor of lysosomal _lpha-mannosidase (IC50: 0.02 micromolar), alkaloid 2, which has been thought to be an intermediate in the biosynthesis of 1, was also a potent inhibitor of _lpha-mannosidase with an IC50 value of 4.6 micromolar.