Peloruside E (22-Norpeloruside A), A Pelorusane Macrolide From The New Zealand Marine Sponge Mycale Hentscheli, Retains Microtubule-Stabilizing Properties

A new peloruside congener, peloruside E (5), has been isolated in sub milligram quantities from a specimen of the New Zealand marine sponge Mycale hentscheli. The structure of 5 differs from the parent compound peloruside A (1) by replacement of the C-10 gem-dimethyl moiety with a monomethyl substituent and represents the first structural deviation in the pelorusane scaffold. Peloruside E (5) is potently antiproliferative (HL-60, IC50 90 nM, cf. 1, 19 nM) and polymerizes purified tubulin, albeit at a rate lower than that of 1.