Autooxidation studies on the marine sesterterpene tetronic acid, variabilin

Autooxidation studies on the sesterterpene variabilin {1} have established that the tetronic acid moiety acts as a sensitizer for the production of singlet oxygen, which then reacts with the furan moiety of variabilin to produce a range of compounds that have been characterized. A comparison of the bioactivity of variabilin with that obtained for some analogues, including the C 21 foranoterpene 25 and some stable oxidation products of 22-O-methylvariabi-lin [8], has shown that neither the furan nor the tetronic acid moiety is essential for the in vitro antiviral activity of variabilin. Structural modifications of variabilin have not eliminated the high cytotoxicity shown by this compound, so that variabilin and related compounds are likely to be of limited use as antiviral agents. © 1989, American Chemical Society. All rights reserved.