A new member of the amphidinol group of  polyketide anti-fungal compounds, Amphidinol 18,  has been isolated by an Italian group lead by Cutignano from the ICB in Naples and its structure partially determined.

The group have been collecting marine protists for several years obtained from commercial sources or by isolation of the dinoflagellates from the Bay of Naples. A methanol extract of a recently acquired sample of A. carterae (CCMP121) demonstrated anti-fungal activity against Candida albicans (32 μg/mL).

Starting with 3.6 g of a cell pellet (which was obtained by centrifugation of 8 L culture medium of the sample, containing around 230,000 cells/mL) was extracted with methanol to give 466 mg of organic material. This was chromatographed and separated into 5 fractions. Examination of the anti-fungal activity identified the active component in fraction 3. This fraction was further chromatographed to give 6.3 mg of the active compound.

Comprehensive NMR analysis identified 5 spin systems COSY/TOCSY correlations and H2BC/HMBC connectivity allowed the structure to be identified as the one above.

Yet another report of an intensive effort in the isolation and structural assignment of a complex natural product. It now remains to complete the work by identifying the stereochemistry of the various substituents. I would guess that they would be similar to previously isolated and synthesised amphidinols, for example, by Oishi et al, who prepared the C31-C40 and C43-C52 units of amphidinol 3.