1- O -Alkylglycerol Ethers from the Marine Sponge Guitarra abbotti and Their Cytotoxic Activity.

The cytotoxicity-bioassay-guided fractionation of the ethanol extract from the marine sponge Guitarra abbotti , whose 1- O -alkyl- sn -glycerol ethers (AGEs) have not been investigated so far, led to the isolation of a complex lipid fraction containing, along with previously known compounds, six new lipids of the AGE type. The composition of the AGE fraction as well as the structures of 6 new and 22 previously known compounds were established using 1 H and 13 C NMR, GC/MS, and chemical conversion methods. The new AGEs were identified as: 1- O -(Z-docos-15-enyl)- sn -glycerol ( 1 ), 1- O -(Z-docos-17-enyl)- sn -glycerol ( 2 ), 1- O -(Z-tricos-15-enyl)- sn -glycerol ( 3 ), 1- O -(Z-tricos-16-enyl)- sn -glycerol ( 4 ), 1- O -(Z-tricos-17-enyl)- sn -glycerol ( 5 ), and 1- O -(Z-tetracos-15-enyl)- sn -glycerol ( 6 ). The isolated AGEs show weak cytotoxic activity in THP-1, HL-60, HeLa, DLD-1, SNU C4, SK-MEL-28, and MDA-MB-231 human cancer cells. A further cytotoxicity analysis in JB6 P + Cl41 cells bearing mutated MAP kinase genes revealed that ERK2 and JNK1 play a cytoprotective role in the cellular response to the AGE-induced cytotoxic effects.