Quercetin, one of the flavonoids family member, can be found in many vegetables, fruits, and beverages with a noticeable nutritional pharmacological properties. This study was aimed to evaluate the ability of quercetin to inhibit lipopolysaccharide (LPS) that induced lethal toxicity in vivo, and to elucidate the importance of the quercetin as an antitumor agent in breast cancer cell line MCF-7.In vivo experiments included the effect of hesperidin and LPS on the liver and spleen of male mice. In the liver, the antioxidant activity was measured by estimating the concentration of glutathione (GSH), and catalase (CAT), while in the spleen, the concentration of cytokines was measured including IL-33 and TNF-α. In vitro experiments included MTT assay, colonogenicity test and Sulforhadamine 101 to assess breast cancer cells morphological apoptosis. The studies revealed the following results: highly significant increase in IL-33 and TNF-αcytokine levels in LPS challenge mice along with significant glutathione (GSH), and catalase (CAT) level increased compared to control group. The cytotoxicity on MCF-7 cell line showed significant differences between groups treated with different concentrations in comparison with control groups in a concentration-dependent manner. The colony measurement test showed that quercetin significantly inhibited colony formation of MCF7 cells compared to control. Apoptotic morphological results showed clear changes in the shape associated with a later stage of apoptosis, including cell shrinking and chromatin condensation. The obtained results indicate that hesperidin might be a potential beneficial compound as a preventive agent