-
[show abstract]
[hide abstract]
ABSTRACT: A variety of Antarctic marine invertebrates contains secondary metabolites that may provide defense against potential predators. However, only in a few cases have tissues, extracts or isolated compounds of these invertebrates been tested against sympatric predators. The Antarctic nudibranch Bathydoris hodgsoni Eliot, 1907 contains hodgsonal, a compound only present in the external body (mantle tissues), which may protect the slugs from predators. To test this defensive hypothesis for hodgsonal, we carried out a series of experiments using the sympatric omnivorous seastar Odontaster validus Koehler, 1906 as a potential predator. Our experiments revealed that natural concentrations of hodgsonal elicit significant feeding deterrent responses in O. validus. Furthermore, hodgsonal is probably biosynthesized de novo by the nudibranch, since it was not detected in the viscera (as it should be in the case of a dietary compound), its concentration in the mantle (0.05-0.15% dry mass) is quite constant in individuals from different localities and depths, and its sequestration from a particular dietary source is unlikely because B. hodgsoni is an omnivorous feeder.
Journal of Experimental Marine Biology and Ecology 10/2000; 252(1):27-44. · 1.88 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Volvatellin (4) is a highly unstable terpene isolated from the extracts of the Indian opisthobranch mollusk Volvatella sp. The structure and the relative stereochemistry of 4 were determined by NMR methods. The paper also describes a hypothetical biosynthesis of 4 starting from the alga-derived caulerpenyne.
Journal of Natural Products 07/1999; 62(6):931-3. · 3.13 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The Patagonian dorid nudibranch Anisodoris fontaini contains in its mantle a series of isocopalane diterpenoid diacylglycerols. Five new minor metabolites, anisodorins 1-5 (1-5), along with the already reported 6 and 7, have been isolated and chemically characterized. The structure and the relative stereochemistries have been determined by spectroscopic means, while the absolute stereochemistries for 2-5 are suggested to be the same as for the biogenetically related major compounds 6 and 7. Synthesis of the enantiomer (8) of anisodorin 1 confirmed the proposed structure and absolute stereochemistry.
Journal of Natural Products 03/1999; 62(2):269-74. · 3.13 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The Patagonian nudibranch Tyrinna nobilis contains a number of terpenoids, the novel seco-11,12-spongiane tyrinnal (1) and the known sesquiterpenoids dendrolasin (2), pallescensin A (3), and dehydropallescensin-2 (4). The metabolites probably derive from dietary sponges, thus suggesting a parallelism between the ecological relationships of T. nobilis and those of mollusks of genus Cadlina. The structure of 1 was determined by spectroscopic methods.
Journal of Natural Products 09/1998; 61(8):1027-9. · 3.13 Impact Factor
