Ottelione A, isolated from the fresh water plant Ottelia alismoides, is a cytotoxic agent at
nanomolar levels against 60 human cancer cell lines. Among other compounds isolated
were a group of novel 1,7-diarylheptanoids. We propose that one of these
diarylheptanoids shares a biogenetic linkage with ottelione A. Namely, we hypothesize
that a spontaneous (i.e., non-enzyme catalyzed) Cope rearrangement, almost entirely
unprecedented in nature, is central to the biosynthesis of ottelione A. The successful
synthesis of the hypothesized biologically relevant diarylheptanoid has now enabled us to
probe its possible biogenetic linkage to ottelione A. During the course of our studies we
have also performed the structure reanalysis of two related hydrienone compounds that
share the exact same core as ottelione A.
Phomopsichalasin, a cytochalasin-like secondary metabolite, was isolated from an
endophytic fungus Phomopsis sp. in 1995. Diporthichalasin, from the endophytic fungus
Diaporthe sp. Bkk3, was isolated several years later in 2007. Both were assigned
different structures and their spectroscopic characterization reported in two different
solvents. By way of detailed NMR analysis and pertinent computational models we have
demonstrated that the structure originally proposed for Phomopsichalasin was incorrect
and is in fact that of the more recently isolated compound Diaporthichalasin.
University of Minnesota Ph.D. dissertation. February 2013. Major: Chemistry. Advisor: Thomas R. Hoye. 1 computer file (PDF); xv, 191 pages.
Brown, Susan G..
Biosynthetic studies of ottelione A and the structural re-analysis of the "Jones isomers"; the structural reassignment of Phomopsichalasin to that of Diaporthichalasin.
Retrieved from the University of Minnesota Digital Conservancy,
Content distributed via the University of Minnesota's Digital Conservancy may be subject to additional license and use restrictions applied by the depositor.