A Soft Spot for Chemistry-Current Taxonomic and Evolutionary Implications of Sponge Secondary Metabolite Distribution

Abstract

Marine sponges are the most prolific marine sources for discovery of novel bioactive compounds. Sponge secondary metabolites are sought-after for their potential in pharmaceutical applications, and in the past, they were also used as taxonomic markers alongside the difficult and homoplasy-prone sponge morphology for species delineation (chemotaxonomy). The understanding of phylogenetic distribution and distinctiveness of metabolites to sponge lineages is pivotal to reveal pathways and evolution of compound production in sponges. This benefits the discovery rate and yield of bioprospecting for novel marine natural products by identifying lineages with high potential of being new sources of valuable sponge compounds. In this review, we summarize the current biochemical data on sponges and compare the metabolite distribution against a sponge phylogeny. We assess compound specificity to lineages, potential convergences, and suitability as diagnostic phylogenetic markers. Our study finds compound distribution corroborating current (molecular) phylogenetic hypotheses, which include yet unaccepted polyphyly of several demosponge orders and families. Likewise, several compounds and compound groups display a high degree of lineage specificity, which suggests homologous biosynthetic pathways among their taxa, which identifies yet unstudied species of this lineage as promising bioprospecting targets.

Keywords: bioactivity; chemotaxonomy; marine sponge; natural product evolution; secondary metabolite.

Figure 1

Phylogenetic distribution of bioactive sponge compounds. Taxa were chosen from a comprehensive list of metabolite-bearing sponge species, independent of their taxon specificity, and were supplemented with further taxa from the respective molecular tree sources where applicable. Colors do not depict relatedness of compounds and were solely chosen for better contrast between different compound classes. Dashed lines indicate reports of compounds suggested for verification. Genus and species names have been adopted from the respective source publications. Particularly for taxa that still await revision, higher-level classification (as given on the branches) might be in conflict with the current reference (World Porifera Database). See text for details.

Figure 1

Phylogenetic distribution of bioactive sponge compounds. Taxa were chosen from a comprehensive list of metabolite-bearing sponge species, independent of their taxon specificity, and were supplemented with further taxa from the respective molecular tree sources where applicable. Colors do not depict relatedness of compounds and were solely chosen for better contrast between different compound classes. Dashed lines indicate reports of compounds suggested for verification. Genus and species names have been adopted from the respective source publications. Particularly for taxa that still await revision, higher-level classification (as given on the branches) might be in conflict with the current reference (World Porifera Database). See text for details.

Figure 1

Phylogenetic distribution of bioactive sponge compounds. Taxa were chosen from a comprehensive list of metabolite-bearing sponge species, independent of their taxon specificity, and were supplemented with further taxa from the respective molecular tree sources where applicable. Colors do not depict relatedness of compounds and were solely chosen for better contrast between different compound classes. Dashed lines indicate reports of compounds suggested for verification. Genus and species names have been adopted from the respective source publications. Particularly for taxa that still await revision, higher-level classification (as given on the branches) might be in conflict with the current reference (World Porifera Database). See text for details.

Figure 2

Selection of exemplary sponge-derived secondary metabolites with potential for taxon specificity. The value and validity of the investigated compound groups are discussed in their respective sections of the text.

Figure 3

Further exemplary sponge-derived secondary metabolites with potential for taxon specificity. The value and validity of the investigated compound groups is discussed in their respective sections of the text.