1989 年 1989 巻 34 号 p. 1-8
In the current research, the inland genus Cassipourea of Rhizophoraceae in Kenya was pinpointed as a target for developing new medicinal resources. The field work on four species of Cassipourea, i. e. Cassipourea malosana, C. gummiflua, C. euryoides, and C. celastroides was carried out during three months in 1987, which all are grown in different habitats each other.
It was proved with detective indicator (PdCl2) at field work that the barks of these trees contain some sulfur compounds as we had expected. The plant materials transfered from field to laboratory provided some sulfur compounds as results of chemical studies such as isolation of compounds and determination of their structures. These compounds were such various alkaloids as pyrrolidine and pyrrolizidine possessing 1, 2-dithiolane ring and bisdisulphide bridge system respectively. Among these alkaloids two new pyrrolidine alkaloids named guinesine-D and euryoidine have been isolated from Cassipourea euryoides. Guinesine-D has also been found in C. celastroides. Another new pyrrolizidine alkaloid named isocassipourine have been isolated from C. malosana and C. gummiflua. For these three compounds, structures 7, 8 and 4 were proposed respectively on the basis of spectroscopic evidence (Fig. 3).
In biological activity screening tests, guinesines and cassipourine exhibited insecticidal activities and inhibitory effects on c-AMP phosphodiesterase (PDE) (Table 2).
