title: Antioxidant properties of quercetin.
abstract: Quercetin, a plant-derived aglycone form of flavonoid glycosides, has been used as a nutritional supplement and may be beneficial against a variety of diseases, including cancer. We examined the antioxidant properties of quercetin. The reduction potential of quercetin was measured at various pH values using voltammetric methods, and its total antioxidant capacity (TAC) was measured using the phosphomolybdenum method. The effect of quercetin on production of reactive oxygen species (ROS) and nitric oxide (NO) in LPS-stimulated human THP-1 acute monocytic leukemia cells was determined by flow cytometry using CM-H2DCFDA dye. The results were compared with curcumin, a natural product exhibiting a similar range of reported health benefits.
  
  
  RESULTS
  1) Quercetin has a higher reduction potential compared with curcumin at three different pH settings and is comparable to Trolox at pH 7-9.5; 2) its TAC is 3.5 fold higher than curcumin; 3) it reduced LPS-induced ROS to near normal levels; 4) it reduced LPS-induced NO production. These data provide a physico-chemical basis for comparing antioxidants, with potential benefits individually or in combination.
authors: Department of Radiation Oncology, University of Florida, 2033 Mowry Road, 103633, Gainesville, FL 32610, USA.
authors: Mei
authors: M
authors: Zhang
authors: Steven G
authors: SG
authors: Swarts
authors: Liangjie
authors: L
authors: Yin
authors: Chaomei
authors: C
authors: Liu
authors: Yeping
authors: Y
authors: Tian
authors: Yongbing
authors: Y
authors: Cao
authors: Michael
authors: M
authors: Swarts
authors: Shanmin
authors: S
authors: Yang
authors: Steven B
authors: SB
authors: Zhang
authors: Kunzhong
authors: K
authors: Zhang
authors: Shaoqing
authors: S
authors: Ju
authors: David J
authors: DJ
authors: Olek
authors: Lisa
authors: L
authors: Schwartz
authors: Peter C
authors: PC
authors: Keng
authors: Rob
authors: R
authors: Howell
authors: Lurong
authors: L
authors: Zhang
authors: Paul
authors: P
authors: Okunieff
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology; D000975:Antioxidants / Q000494:pharmacology*; D003474:Curcumin / Q000494:pharmacology; D005434:Flow Cytometry; D006801:Humans; D007948:Leukemia, Monocytic, Acute / Q000188:drug therapy* / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology; D008928:Mitochondria / Q000187:drug effects* / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism; D010084:Oxidation-Reduction; D011794:Quercetin / Q000494:pharmacology*; D017382:Reactive Oxygen Species / Q000378:metabolism; D014407:Tumor Cells, Cultured
chemical_list: D000970:Antineoplastic Agents; D000975:Antioxidants; D008070:Lipopolysaccharides; D017382:Reactive Oxygen Species; D009569:Nitric Oxide; D011794:Quercetin; D003474:Curcumin