Ursolic acid and its structural isomer oleanic acid, which were isolated from Tembesu (Fragraea fragrans) fruit, had been oxidiced to 3-oxourson-12-en-28-oic acid [3-oxoolean-12-en-28-oic acid] with Jones’ reagent (K^C^O?, H2SO4 and aceton, with 18% yield). The products are then applied in antibacterial activity test to against gram positive and gram negative bacteria. The test result of the …