Further chemical studies on terpenoid acylglycerols from the Antarctic nudibranch Austrodoris kerguelenensis.

The diterpenoid acylglycerol fraction from an extract of the mantle of a new collection of the Antarctic dorid gastropod mollusc Austrodoris kerguelenensis has been chemically analysed. The novel 2-monoacyl glycerol 11, along with known 1,2-diacyl glyceryl esters 5 and 6, now reassigned as 7 and 8, have been isolated. All compounds are characterized by the linkage of a diterpenoid moiety at C-2 of glycerol. Because the R absolute stereochemistry at C-2 of glycerol has been established for the corresponding 1,3-glyceryl esters 1 and 2, derived from 7 and 8 by acyl-migration of the terpenoid moiety from C-2 to C-3, our finding implies that 1,2-derivatives from Antarctic nudibranchs have the same S stereochemistry as all 1,2-sn-diacylglycerols from the other dorids.