New potent cytotoxic lamellarin alkaloids from Indian ascidian Didemnum obscurum

Abstract

Chemical investigations of the ascidian Didemnum obscurum has resulted in the isolation of four new lamellarin alkaloids, lamellarin-ζ ( 1 ), lamellarin-η ( 2 ), lamellarin-ϕ ( 3 ) and lamellarin-χ ( 4 ) along with seven known lamellarins, lamellarin-K ( 5 ), lamellarin-I ( 6 ), lamellarin-J ( 7 ), lamellarin-K triacetate ( 8 ), lamellarin-L triacetate ( 9 ), lamellarin-F ( 10 ) and lamellarin-T diacetate ( 11 ). The structures of the compounds 1– 11 were established by detailed analysis of NMR spectral data. Cytotoxic activity of the isolates has been done against coloractal cancer cells.