Mango (Mangifera indica L.) belonging to Anacardiaceae family is a tropical plant, common distribution in Vietnam. Mangiferin (1) was isolated from the leaves of Mangifera indica L. by reflux extraction and ultrasound-assisted extraction methods Chemical structure of compound 1 was identified by means of spectroscopic methods including electrospray ionization mass spectrometry (ESI-MS) and nuclear magnetic resonance spectroscopy (NMR). Compound 1 is showed DPPH scavenging activity with SC50 value of 15.94 g/ml and moderate cytotoxic activity on four human cancer cell lines including mouth epidermal carcinoma (KB), liver hepatocellular carcinoma (Hep-G2), lung carcinoma (LU-1) and breast cancer (MCF7) with IC50 values of 11.95, 13.75, 15.65 and 16,84 g/ml.