Chemical Biodiversity and Bioactivities of Saponins in Echinodermata with an Emphasis on Sea Cucumbers (Holothuroidea)

Abstract

Echinoderms are a source of a broad range of secondary metabolites with a large variety of bioactive properties. Although pigment and lipid derivatives are the major groups of bioactive compounds found in crinoids and ophiuroids, saponins represent the most abundant and diverse marine natural products (MNPs) in the phylum Echinodermata. This review is for researchers that are interested in MNPs derived from echinoderms, but with a particular focus on the structural diversity and biological function of saponins. Among the echinoderms, these steroidal compounds are mostly known for and structurally most diverse within sea cucumbers. Through compilation of extensive tables, this review provides a reference book, summarizing not only the major chemical classes of well-known secondary metabolites in the phylum Echinodermata but also further focusing on the presence of bioactive saponins in echinoderms in general and within different sea cucumber species in particular. The final compilation aims to correlate the vast structural diversity of saponins with known biological functions. The here presented data revealed that holothurians, holotoxins, cucumariosides, and echinosids are not only the most abundant saponin compounds in various genera of sea cucumbers but that these saponins can also be used as potential chemotaxonomic markers for different sea cucumber species. By studying the structure-function relationships of triterpene glycosides in echinoderms in general, or in particular within holothurians, the vast structural diversity, taxonomic distribution, and bioactivity of the molecules can be deciphered, which provides an opportunity to focus future research efforts on target species that contain MNPs with novel pharmacological activities.

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

“…Steroidal saponins and glycosides, besides being commonly found in many Echinodermata [ 87 ], also have been reported in sponges. Since the compounds have been mainly reported from specimens of the suborder Astrophorina, they were initially considered as evolutionary characteristics for this clade but were disregarded due to studies from non-tetractinellid genera [ 46 , 88 ].…”

“…As Ivanchina et al [89] stated, there are, however, major structural differences among glycosides in sponges, with sparse reports of these metabolites outside of Astrophorina possibly being rare homologs. Although all recent metabolites reports refer to Astrophorina, the aforementioned outliers (e.g., Pandaros, Niphates, Ectyoplasia) should not be disregarded, hence rendering the specificity of these metabolites questionable [90][91][92], especially when taking into account their occurrence in other invertebrates [87]. Likewise, triterpenoid saponins, which also commonly occur in echinoderms, are frequently found in the suborder of Astrophorina, especially among members of the family Geodiidae, e.g., [93,94].…”

Development and Interrogation of a Transcriptomic Resource for the Giant Triton Snail (Charonia tritonis)

“…C. tritonis are one of the few active predators of adult COTS (De Lange et al 1997), due in large part to their capacity to detoxify saponins, a family of defensive chemicals present within starfish and other echinoderms (Kamyab et al 2019). The CYP450 enzyme system of molluscs (and other phyla) are widely involved in molecule biosynthesis and biotransformation of xenobiotics and are also key to many developmental processes (Jia et al 2002;Rewitz et al 2006).…”

Ten-Year Research Update Review: Antiviral Activities from Marine Organisms

“…Echinoderm-derived natural products were mostly sulfated compounds that can be classified into two mayor groups, aromatics and saponins. In the last decade, saponins isolated from sea cucumbers are receiving a greater attention due to their interesting biological features [225,226]. Conversely, aromatic sulfated compounds were mostly reported in crinoids and ophiuroids as pigments deriving from anthraquinones or naphthoquinones [227].…”