Abstract. The antimutagenic activity of SesbaniajavanicaMiq. or Sano, an edible vegetable flowerDMSO extract against aflatoxin B1 (AFB1) benzo (a) pyrene [B(a)P], was evaluated by means of theAmes’ test. The SesbaniajavanicaMiq. flower DMSO extract showed a strong inhibitory effect againstAFB1 and B(a)P mutagens. A search to isolate the major flavonoid in Sesbaniajavanica Miq. flowerextract found the flavonol glycoside, Quercetin 3-2G-rhamnosylrutinoside, which was confirmed byits physicochemical properties as a major constituent of the flower. Quercetin 3-2G-rhamnosylrutinoside (207 μg/plate) also showed a strong inhibitory effect against AFB1and B(a)Pwith a more than 70% inhibition rate