Abstract Oxidative stress may be a key factor in the onset of certain diseases, including cancer. Oxy-radicals play important roles in the initiation, promotion, and progression of carcinogenesis. During the course of DNA excision and repair of oxidized, deaminated or alkylated bases apurinic/apyrimidinic (AP) or abasic sites are formed. The flavonoid quercetin was investigated for its ability to inhibit the oxidation of plasmid from Pectobacterium carotovorum KD 100 and Agrobacterium tumefaciens GV 3103 using the Fenton's chemistry. Utilizing a Colorimetric Assay Kit (Oxford Biomedical Research #FR09, Oxford, MI) for DNA damage quantification, AP sites were measured for plasmid following incubation with low doses of quercetin (1, 2, 2.5, 3, 3.5 µM) or without for 12 or 24 hr. With the increasing concentrations of quercetin the number of AP sites in each sample significantly decreased more for Pectobacterium carotovorum KD 100 compared to Agrobacterium tumefaciens GV 3103 in a time- and dose-dependent manner in comparison to their respective controls for the 12 and 24 hr incubation periods. The differences in decrease in AP sites can be linked to structural differences between the two bacterial strains and/or decreased oxidation for each sample with increased quercetin aliquots. Citation Information: Mol Cancer Ther 2013;12(11 Suppl):C60. Citation Format: William Y. Boadi, Damitea Johnson, Korsi Dumenyo. Exposure of low doses of quercetin on DNA oxidation in Pectobacterium carotovorum KD 100 and Agrobacterium tumefaciens GV 3103. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr C60.