Introduction: Bioassay-guided isolation of the bioactive components from Equisetum debile Roxb. (“sumbak”) was conducted. Objectives: This study aimed to isolate and characterize bioactive components from E. debile. Materials and Methods: Ethanolic extract of whole plant sample of E. debile was sequentially partitioned to obtain the bioactive choroform-soluble (EdC) partition. EdC was purified via chromatographic techniques. Fractions obtained after purification were analyzed for cytotoxic and antioxidant properties. Brine shrimp lethality as well as in vitro antioxidant assays such as 2,2-diphenyl-1-picrylhydrazyl (DPPH) Radical Scavenging, Total Antioxidant Capacity and Total Phenolics Content assays were carried out. One-Dimensional (1D) and two-dimensional NMR and LC-MS analyses were conducted to elucidate structure of the isolated compound. Results and Discussion: The whole plant sample of E. debile afforded herniarin. Conclusion: The present findings imply that E. debile can be a potential source of bioactive components.