Every plant has immense potentials hidden in them. For making use of the plant and their derivatives we must have a deep knowledge of components present in them and the properties they have. In addition to traditional uses, they may have other uses. The current study focuses on the two commonly seen knot weeds, Persicaria barbata (L.) H. Hara and Persicaria glabra (Willd.) M. Gómez. The cytotoxic potential of both the plants is analyzed by Allium cepa assay revealing clastogenic and non-clastogenic abnormalities. In vitro antioxidant studies are carried out by using modified FRAP analysis. Both the plants showed concentration-dependent significant antioxidant potential. To identify the phytochemicals responsible for cytotoxicity and antioxidant properties of the plants, both preliminary phytochemical analysis and HR - LC/MS analysis are carried out. LC/MS analysis identified 176 compounds from P. barbata and 227 compounds from P. glabra. The findings of the study suggest that theP. barbata and P. glabra are the most promising plants in future, which can be used to develop potential antitumour promoting substances or for the production of therapeutic drugs for curing cancer.