This research work deals with of the synthesis of 5,7,8- trihydroxyflavone from chrysin by persulfation and the study of its in vitro antioxidant and antibacterial activity. The antioxidant effect was evaluated by induced lipoperoxidation in human erythrocyte membranes. The antibacterial effect was determined by the modified Kirby-Bauer agar diffusion method. The 5,7,8-trihydroxyflavone was obtained with a yield of 11,4 % and its structure was elucidated by NMR. The product showed antioxidant activity at 833 μg/mL (14,17 ± 7,12 nmol MDA/g Hb) and 167 μg/mL (55,24 ± 16,04 nmol MDA/g Hb) compared to the control (108,62 ± 18,85 nmol MDA/g Hb). The product proved to be active against Staphycoccus aureus (20,10 ± 1,66 mm) at a concentration of 125 µg/ 20 µL and showed no activity against Escherichia coli, Pseudomonas aeruginosa, Bacillus cereus and Salmonella thipi.