Introduction:Eichhornia crassipes(E. crassipes) are a longstanding hydrophyte belonging to the Pontederiaceae family and subfamily Trollioideae. It is classified as an invasive plant owing to its phenomenal growth and propagation and is often described as the worst aquatic plant. Natural antioxidants, such as phenolic compounds and flavonoids, have an increased protective effect against free radicals. A single laboratory test is insufficient to comprehend all of the mechanisms entailed in investigating the antioxidant effects of the phytoconstituents. The antioxidant propensity of methanolic extracts fromE. crassipespetioles was investigated in this study utilizing 2,2'-Azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 1,1-diphenyl-2-pycryl-hydrazyl (DPPH). Additionally, the cytotoxic effect ofE. crassipesmethanolic petiole extract upon MG-63 cell lines for the inhibition of osteosarcoma cells was investigated.Materials and methods: The antioxidant propensity was appraised by employing DPPH and ABTS assays. The cytotoxic effects of the methanolic petiole extract ofE. crassipesat varying concentrations on MG-63 cell lines were evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide assay. The absorbance scores were computed using the mean and standard deviation. The half-maximal inhibitory concentration (IC50) was calculated by applying probit analysis. The data were analyzed using SPSS Statistics for the descriptive statistics of the percentage of cell viability and regression analysis.Results: The antioxidant potential was assessed by employing DPPH and ABTS assays at various concentration levels of 50 μg/ml, 100 μg/ml, 200 μg/ml, and 400 μg/ml of methanolic petiole extracts. The antioxidant potential of DPPH (57.95%) and ABTS (60.47%) was more at the elevated doses of 400 μg/mL. The percentage of cell viability upon MG-63 cell line was measured at varying doses of 12.5 μg/ml, 25 μg/ml, 50 μg/ml, 100 μg/ml, and 200 μg/ml of methanolic petiole extracts and was found to be 99.36%, 93.92%, 86.77%, 69.14%, and 45.08%, respectively. The IC50 value for the extract ofE. crassipesagainst the MG-63 cell line was 177.65 μg/mL. The regression equation computed from the findings of the probit analysis was y = -0.2881x + 101.18 with a coefficient of determination of R² = 0.992.Conclusion: The methanolic extracts of the various parts of the plant, such as leaves, flower, rhizome, and petioles, have been established in similar prior studies to contain the highest phenolic constituents and were found to have a high rate of DPPH radical scavenging activity and reducing power. It is inferred from the findings of the present study thatE. crassipespetiole extracts have a significant protective role against oxidative stress, potentially attributed to the antioxidant potential. Further, the findings of the study reveal that the methanolic petiole extract ofE. crassipesinduced cytotoxicity upon MG-63 cell lines with an IC50 value of 177.65 μg/mL.