Asteroid Saponins: A Review of Their Bioactivity and Selective Cytotoxicity

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.