Siphonaria species

Pulmonates are air-breathing molluscs that do not include many families and genera [68]. Siphonaria species from many distinct geographical areas possess a series of secondary metabolites with polypropionate skeletons characterized by the presence of ketal, pyrone and furanone moieties [47]. A rigorous biosynthetic experiment [69] proved that Siphonaria denticulata is able to... 

Diemenensin-A (882) inhibited Staphylococcus aureus and Bacillus subtilis at 1 pg/disc and 5 pg/disc, respectively, and inhibited cell division in the fertilized sea urchin egg assay at 1 pg/mL. Another new polypropionate antibiotic with a y-hydroxy-a-pyrone ring, pec-tinatone (884) was isolated from Siphonaria pectinata (592). S. denticu-lata furnished two isomeric polypropionate metabolites, denticulatin A (885) and B (886) (593). Denticulatin A (885) was ichthyotoxic at 10 pg/mL while 886 was reported to be toxic at 30 pg/mL. Norpectina-tone (887) and the E- and Z-isomers 888 and 889 of a related furanone were constituents of the Chilean pulmonate S. lessoni (594), and a cyclic hemiacetal (890) as well as an associated ketol ester (891) were reported as metabolites of S. australis (595). Hochlowski et al. (596) investigated four other Siphonaria species and isolated siphonarin-A (892)... 

In addition to siphonarin A [140], the fljian mollusk Siphonaria normalis has been reported to contain an unusual tricyclic ketal with a trioxaadamantane ring skeleton. The structure of muamvatin 2 [161] was determined by nmr spectroscopy (118). The possible roles of the polypropionate metabolites isolated from S honaria species could be associated with its trailfollowing habits along with defense against predators. 

---