Background: Bistorta amplexicaulis is a seasonal herb with several folkloric uses. The plant extract has been shown to possess various activities including antioxidant, anticancer, anti-bacterial, anti-fungal, cardio-protective, anti-atherosclerosis activities. Objective: The aim of the study was to quantify the activity of the plant extract and relate it to the activity of the isolated compounds, gallic acid. Methods: Extraction of the plant was carried out. Then the activity of the extract was compared with its constituent, gallic acid. Cytotoxic potential of the two against human liver cancer cell line (HepG2), breast cancer cell line (MCF-7) and human umbilical vein endothelial cells (HUVEC) was evaluated through MTS assay. Results: The extract had better activity against HepG2 as compared to gallic acid (IC50 29µg/mL vs 37µg/mL). It also provided a better therapeutic window by having lower toxicity for HUVEC cells than gallic acid (IC50 63µg/mL vs 47µg/mL) suggesting the use of the extract over the purified gallic acid for these cells. We also performed the fluorescence study of the rhizome extract in ethanol (REE), methanol (REM), 80% ethanol (80RE), 80% methanol, (80RM) and acetone (RAC). The highest intensity of fluorescence was found in REE with excitation at 394 nm and emission at 421nm. Conclusion: The comparison of gallic acid with ethanolic rhizome extract of B. amplexicaulis reveals important insights about utilizing the plant extract over purified gallic acid. The ethanolic extract also has the potential to be used as autoflouresent drug during in vitro and in vivo studies.