Background: Relaxins are a family of peptides that regulate reproductive physiology in vertebrates. Evidence that this is an evolutionarily ancient role of relaxins has been provided by the discovery of two relaxin-like gonad-stimulating peptides (RGP1 and RGP2) that trigger spawning in starfish. The main aim of this study was to identify the receptor(s) that mediate(s) the effects of RGP1 and RGP2 in starfish. Results: Here we show that RGP1 and RGP2 belong to a family of peptides that include vertebrate relaxins, Drosophila insulin-like peptide 8 (Dilp8), and other relaxin-like peptides in several protostome taxa. An ortholog of the human relaxin receptors RXFP1 and RXFP2 and the Drosophila receptor LGR3 was identified in starfish (RXFP/LGR3). In Drosophila, but not in humans and other vertebrates, there is a paralog of LGR3 known as LGR4, and here an LGR4-type receptor was also identified in starfish. In vitro pharmacological experiments revealed that both RGP1 and RGP2 act as ligands for RXFP/LGR3 in the starfish Acanthaster cf. solaris and Asterias rubens, but neither peptide acts as a ligand for LGR4 in these species. Conclusions: Discovery of the RXFP/LGR3-type receptor for RGP1 and RGP2 in starfish provides a new insight into the evolution of relaxin-type signaling as a regulator of reproductive processes. Furthermore, our findings indicate that RXFP/LGR3-type receptors have been lost in several phyla, including urochordates, mollusks, bryozoans, platyhelminthes, and nematodes.

Saponins encompass a diverse group of naturally occurring glycoside molecules exhibiting amphiphilic properties and a broad range of biological activities. There is a resurgence of interest in those saponins produced by marine organisms based on their potential therapeutic benefits, application in food products and most recently their potential involvement in intra- and inter-species chemical communication. The continual advancements in liquid chromatography techniques and mass spectrometry technologies have allowed for greater detection rates, as well as improved isolation and elucidation of saponins. These factors have significantly contributed to the expansion in the catalogue of known saponin structures isolated from marine invertebrates; however, there currently exists no specific chemical library resource to accelerate the discovery process. In this study, a Marine Animal Saponin Database (MASD v1.0) has been developed to serve as a valuable chemical repository for known marine saponin-related data, including chemical formula, molecular mass and biological origin of nearly 1000 secondary metabolites associated with saponins produced by marine invertebrates. We demonstrate its application with an exemplar asteroid extract (Acanthaster cf. solaris, also known as crown-of-thorns starfish; COTS), identifying saponins from the MASD v1.0 that have been previously reported from COTS, as well as 21 saponins isolated from multiple other related asteroid species. This database will help facilitate future research endeavours, aiding researchers in exploring the vast chemical diversity of saponins produced by marine organisms and providing ecological insights, and the realisation of their potential for various applications, including as pharmaceuticals. Graphical Abstract

Saponins are a diverse class of secondary metabolites that are often reported to exhibit a variety of pharmacological applications. While research into the elucidation and application of plant and class Holothuroidea-derived saponins (i.e., sea cucumbers) is extensive, the class Asteroidea-derived saponins (i.e., seastars) have been largely overlooked and primarily limited to elucidation. This review provides a comprehensive overview of the cytotoxic activities of asteroid-derived saponins against various cell cultures, for instance, mammalian erythrocytes, multiple microbial strains and cancer cell lines, including melanoma, breast, colon, and lung cancers. Highlighting the distinct structural variations in these saponins, this review examines their selective cytotoxicity and potency, with many demonstrating IC₅₀ values in the low micromolar range. Specific compounds, such as asterosaponins and polyhydroxylated saponins, exhibit noteworthy effects, particularly against melanoma and lung carcinoma cells, while triterpenoid saponins were found to be highly cytotoxic to both erythrocytes and fungal cells. This review also addresses gaps in the research area, including the need for additional in vitro antimicrobial studies, in vivo studies, and further exploration of their mechanisms of action. By consolidating recent findings, we have shed light on the therapeutic potential of asteroid-derived steroidal saponins in developing novel antimicrobial and anticancer agents.

Colorectal cancer treatment primarily relies on chemotherapy, which often causes significant side effects. Sacha inchi, a plant known in traditional medicine, has shown promise in various therapeutic applications. However, despite its potential, the specific mechanisms remain poorly understood, particularly regarding its husk components. This study investigates sacha inchi husk extract’s chemical properties and its effects on human colorectal cancer cells. GC/MS and LC/MS analyses revealed a rich profile of phenolic and flavonoid compounds, with naringenin and lidocaine as predominant components. The extract demonstrated significant dose-dependent inhibition of colorectal cell migration, invasion, and colony formation while exhibiting no cytotoxicity toward normal colon epithelial cells. Transcriptomic and proteomic analyses showed downregulation of migration- and invasion-related genes in cancer cells, and Western blot analysis confirmed reduced expression of MMP2, MMP9, and N-cadherin. EGFR pathway analysis showed decreased expression of RAS (−0.2-fold), MAK (−0.26-fold), and ERK (−0.54-fold) genes, indicating suppression of epithelial–mesenchymal transition (EMT). These findings demonstrate that sacha inchi husk extract effectively inhibits metastasis in colorectal cancer cells through the upstream (EGFR) and downstream (EMT) pathways, suggesting its potential as a dietary supplement or therapeutic agent for colorectal cancer treatment. Our research provides evidence for the development of natural, less toxic alternatives.

With an aging population and the increase in life expectancy, colorectal cancer is becoming increasingly common. Currently, the mainstay of treatment is chemotherapy, which can cause a variety of side effects. However, herbalists in many cultures have long used herbs to promote health and treat various diseases, including colon cancer. This study investigated the chemical components of shell extracts from Plukenetia volubilis (sacha inchi) and their effects on colon cancer cells. First, cytotoxicity against both normal and cancer cells was assessed, followed by cell migration and invasion. Finally, transcriptomic and proteomic analyses were performed to investigate molecular mechanisms. Phytochemical analysis showed a total phenolic content of 134.61 ± 0.27 mgGAE/g extract and a total flavonoid content of 5.75 ± 0.01 mgQE/g extract; moreover, lidocaine (10.57%) and linolenic acid (10.39%) were identified as the most abundant compounds. In vitro, the extract inhibited cell migration, invasion, and colony formation and was associated with potential modulations of the Hippo pathways and epithelial–mesenchymal transition. Therefore, it can be concluded that these extracts are effective in inhibiting the progression of colon cancer cells, and thus, they can prospectively be developed as a dietary supplement or therapeutic agent for the treatment of colon cancer in the future.