Cytotoxic Activity and In Silico Study of Secondary Metabolites Derived from Dactylospongia elegans

Breast cancer remains a major global health burden. Dactylospongia species have been explored for their cytotoxic potential. This study aims to evaluate the cytotoxic potential of compounds derived from the marine sponge Dactylospongia elegans. Dactylospongia elegans were collected from the Lembeh Strait, macerated using methanol, then partitioned to an ethyl acetate fraction. The cytotoxic activity of these fractions was assessed using MDA-MB-231 cells while toxicity testing was done using the BSLT. TLC was carried out to determine the groups of compounds, while LC-MS/MS was used to predict active compounds contained in the ethyl acetate fractions. In silico studies were conducted as preliminary studies to determine the antitumor mechanism. The ethyl acetate fraction and F4 subfraction of Dactylospongia elegans exhibited cytotoxicity toward MDA-MB-231 cells with IC50 values of 15.72 and 41.76 µg/mL, respectively. The BSLT indicated the strongest toxicity belongs to the F6 subfraction (LC50 = 32.831 µg/mL). TLC analysis confirmed the presence of major secondary metabolites as terpenoids, steroids, and alkaloids, then confirmed with LC-MS/MS including 5-epi-illimaquinone and calciferol. Molecular docking revealed that calciferol exhibited the strongest binding affinity toward tyrosine kinase and p53–MDM2 receptors, with binding energies of −10.13 and −10.28 kcal/mol, respectively. These findings suggest that Dactylospongia elegans contains bioactive constituents with potential anticancer activity, particularly against TNBC.