Biochemical trade-offs: evidence for ecologically linked secondary metabolism of the sponge Oscarella balibaloi.

Secondary metabolite production is assumed to be costly and therefore the resource allocation to their production should be optimized with respect to primary biological functions such as growth or reproduction. Sponges are known to produce a great diversity of secondary metabolites with powerful biological activities that may explain their domination in some hard substrate communities both in terms of diversity and biomass. Oscarella balibaloi (Homoscleromorpha) is a recently described, highly dynamic species, which often overgrows other sessile marine invertebrates. Bioactivity measurements (standardized Microtox assay) and metabolic fingerprints were used as indicators of the baseline variations of the O. balibaloi secondary metabolism, and related to the sponge reproductive effort over two years. The bioactivity showed a significant seasonal variation with the lowest values at the end of spring and in early summer followed by the highest bioactivity in the late summer and autumn. An effect of the seawater temperature was detected, with a significantly higher bioactivity in warm conditions. There was also a tendency of a higher bioactivity when O. balibaloi was found overgrowing other sponge species. Metabolic fingerprints revealed the existence of three principal metabolic phenotypes: phenotype 1 exhibited by a majority of low bioactive, female individuals, whereas phenotypes 2 and 3 correspond to a majority of highly bioactive, non-reproductive individuals. The bioactivity was negatively correlated to the reproductive effort, minimal bioactivities coinciding with the period of embryogenesis and larval development. Our results fit the Optimal Defense Theory with an investment in the reproduction mainly shaping the secondary metabolism variability, and a less pronounced influence of other biotic (species interaction) and abiotic (temperature) factors.

Antifouling properties of simple indole and purine alkaloids from the Mediterranean gorgonian Paramuricea clavata.

Chemical investigation of the Mediterranean gorgonian Paramuricea clavata resulted in the isolation of two new alkaloids, 2-bromo-N-methyltryptamine (1) and 3-bromo-N-methyltyramine (2), together with nine known compounds (3-10 and linderazulene). The bromoindole derivative 3 is reported herein for the first time from a natural source. The chemical structures of these compounds were assigned by spectroscopic analyses and comparison with literature values. The antifouling activity and toxicity of compounds 1-10 were assessed using three marine biofilm bacteria and the Microtox assay. In contrast to commercial antifoulants, bufotenine (5) and 1,3,7-trimethylisoguanine (10) showed significant antiadhesion activity against one bacterial strain while being nontoxic.

Acylated triterpene saponins from the roots of Securidaca longepedunculata.

Four triterpene saponins, 3-O-beta-D-glucopyranosylpresenegenin 28-O-beta-D-apiofuranosyl-(1-->3)-beta-d-xylopyranosyl-(1-->4)-[beta-D-apiofuranosyl-(1-->3)]-alpha-L-rhamnopyranosyl-(1-->2)-{4-O-[(E)-3,4,5-trimethoxycinnamoyl]}-beta-D-fucopyranosyl ester, 3-O-beta-D-glucopyranosylpresenegenin 28-O-beta-D-apiofuranosyl-(1-->3)-beta-D-xylopyranosyl-(1-->4)-[beta-D-apiofuranosyl-(1-->3)]-alpha-L-rhamnopyranosyl-(1-->2)-[(6-O-acetyl)-beta-D-glucopyranosyl-(1-->3)]-{4-O-[(E)-3,4,5-trimethoxycinnamoyl]}-beta-D-fucopyranosyl ester, 3-O-beta-D-glucopyranosylpresenegenin 28-O-beta-D-apiofuranosyl-(1-->3)-beta-D-xylopyranosyl-(1-->4)-[beta-D-apiofuranosyl-(1-->3)]-alpha-L-rhamnopyranosyl-(1-->2)-[beta-D-galactopyranosyl-(1-->3)]-{4-O-[(E)-3,4,5-trimethoxycinnamoyl]}-beta-D-fucopyranosyl ester, and 3-O-beta-D-glucopyranosylpresenegenin 28-O-beta-D-apiofuranosyl-(1-->3)-[alpha-L-arabinopyranosyl-(1-->4)]-beta-D-xylopyranosyl-(1-->4)-[beta-D-apiofuranosyl-(1-->3)]-alpha-L-rhamnopyranosyl-(1-->2)-{4-O-[(E)-3,4,5-trimethoxycinnamoyl]}-beta-D-fucopyranosyl ester, were isolated from the roots of Securidaca longepedunculata, together with three known compounds. Their structures were established mainly by 2D NMR techniques and mass spectrometry.