Tetramic acid from Melophlus sarassinorum

Wang, C.Y., Wang, B.G., Wiryowidagdo, S., Wray, V., van Soest, R., Steube, K.G., Guan, H.S., Proksch, P., and Ebel, R. 2003. Melophlins C-O, thirteen novel tetramic acids from the marine sponge Melophlus sarassinorum. J. Nat. Prod. 66, 51-56. 

Tetramic acid can be considered as a y-methylene lactam in which the methylene is an enol stabilized by the presence of a second carbonyl group tetramic acid thus consists of two tautomeric forms in equilibrium. Melophlins A and B, isolated from Melophlus sarassinorum collected in Indonesia, are tetramic acids substituted with... 

Aoki, S., Higuchi, K., Ye, Y, Satari, R., and Kobayashi, M. (2000) Melophlins A and B, novel tetramic acids reversing the phenotype of ras-transformed cells, from the marine sponge Melophlus sarassinorum. Tetrahedron, 56,1833-1836,... 

---