STRUCTURE ELUCIDATION OF LOLITREM-F, A NATURALLY-OCCURRING STEREOISOMER OF THE TREMORGENIC MYCOTOXIN LOLITREM-B, ISOLATED FROM LOLIUM-PERENNE INFECTED WITH ACREMONIUM-LOLII

A new lolitrem, lolitrem F (2), was isolated from endophyte-infected p erennial ryegrass. Its structure was shown by mass spectrometry and on e- and two-dimensional NMR spectroscopy to be a 31,35-cis-fused isomer of lolitrem B. Base-catalyzed epimerization of 2 and lolitrem B (1) a fforded their 31-epimers (4 and 3, respectively). Comparison with spec tral data for 1 and 31-epi-lolitrem B (3) established lolitrem F to be 35-epi-lolitrem B. Compounds 1, 2, and 4 were equally tremorgenic in a mouse bioassay, but 3 was nontremorgenic. Base-catalyzed exchange of II-Si was found to permit efficient incorporation of deuterium (and p otentially, therefore, of tritium) into 1 and 3.