A novel lupane-type triterpene ''Diospyrosonate'' (P1) has been isolated from anti-inflammatory activity guided fractionation of petroleum ether extract precipitate of Diospyros malabarica stem bark with a gradient of ethyl acetate in petroleum ether. Further P1 was screened for anti- inflammatory activity on carrageenan and dextran induced inflammation model in rats at the dose level of 50 mg/kg body weight. Treatment of inflammed rats with P1 has showed significant reduction in inflammation caused by carrageenan (P<0.05) and dextran (P<0.01). Hence P1 can be considered as the principle component responsible for the anti-inflammatory activity for Diospyros malabarica bark.The characterization of P1 was done by spectral studies like IR, 1H-NMR, 13C-NMR & mass spectroscopy. On the basis of spectral studies the structure of P1 has been elucidated as Betulin esterified at C-29 with a C-14 acid. This is a novel triterpenoid isolated from the bark of D. malabarica for the first time and given a trival name Diospyrosonate.