Mangosteen (Garcinia mangostana Linn.) belongs to the family Guttiferae. In the present study, crude methanolic mangosteen fruit rind extract was analyzed for its active constituents using thin layer Chromatography (TLC), Fourier transform infrared spectroscopy (FTIR) and Liquid chromatography–Mass spectrometry (LC–MS). Antioxidant potential of the extract was studied using: various biochemical assays, VERO & HELA cell lines, and animal models such as immuno-toxicity-induced albino mice, fishes. Larvicidal activity of the extract was also studied against the 3 and 4 instar larvae of the mosquito (Culex quinquefasciatus). TLC studies indicated the presence of 7 active fractions in the crude extract. FTIR analyses revealed the presence of aromatic Cdouble bond; length as m-dashC, C–O, –C–H (alkyl), and –OH as the main functional groups in all. LC–MS analysis revealed the presence of xanthones and other flavonoids. Total phenolic content was determined and found that the extract contained significantly large amount of phenolics: 5.95 ± 0.54 w/w of extract, which can be correlated to their antioxidant activities at three different concentrations such as, 30 mg (0.807 ± 1.05) 20 mg (0.612 ± 1.32) and 10 mg (0.425 ± 0.12) as the gallic acid equivalents. The extract showed a strong DPPH free