These “pederinelike
molecules” now number more than 34 from at least 8
different animal genera, and full details on these symbiotic
sources together with a discussion of the range of anti-tumor
agents isolated from marine organisms that closely resemble
bacterial metabolites,29 are given in the 2004 review by Piel;93
an updated review from the same author covering the
literature to the end of 2007 was also recently published.98
These articles should be consulted in order to see the wide
range of structures and potential producers that have so far
been identified, and to see what can now be done using this
information to produce novel but unnatural variations on
known potential anti-cancer agents from these sources. For
example, reaction of mycalamide A (35; Scheme 8) with
the PedO gene product has generated the novel biosynthetic
hybrid, 18-O-methylmycalamide A (36; Scheme 8), which
has increased cytotoxicity compared to the parent compound