Metastatic Inhibitory and Radical Scavenging Efficacies of Saponins Extracted from the Brittle Star (Ophiocoma erinaceus). Echinodermata use saponins in chemical defense against pathogens and predators. The molecular mechanisms of antimetastatic effects of brittle star saponins are still unknown. The present study examined antioxidant capacity and invasive ability in HeLa carcinoma cells exposed to brittle star crude saponins. Discolorating methods with DPPH and ABTS and expression of SOD-2 with RT-PCR were used to estimate the antioxidant activity. The anti-invasive activity of extracted saponins was examined through adhesion of HeLa cells to extracellular matrix, wound healing and evaluation of the mRNA levels of MMP-2 and MMP-9 by real time-PCR. The results showed that extracted saponins had cytotoxicity against cervical cancer cells and ABTS and DPPH scavenging properties with IC50 values of 604.5, 1012 μg/ml, respectively. Further, we found that, in wound healing assay, brittle star saponins could prevent invasion of HeLa cells in a concentration dependent manner. Furthermore, cell adhesion assay demonstrated blockage of cell attachment to extracellular matrix with an IC50 concentration of 16.1μg/ml. The significant dose dependent down regulation of MMP-2 and MMP-9 in treated cells demonstrated that isolated saponins can decline tumor metastasis in vitro. The brittle star saponins remarkably prevented cervical cancer invasion and migration associated with down regulation of matrix metalloproteinase expression. Therefore, saponins could be suggested as an anti-invasive candidate against cervical cancer and an antioxidant as well.