title: Delivering flavonoids into solid tumors using nanotechnologies.
abstract: BACKGROUND
  Long-term epidemiological studies have demonstrated that regular ingestion of flavonoids contained in dietary sources is associated with a reduced risk for many chronic diseases including cancer. However, although flavonoids are largely consumed in the diet and high concentrations may exist in the intestine after oral administration, the plasma/tissue concentrations of flavonoids are lower than their effective therapeutic doses due to poor bioavailability, resulting in the limited efficacy of flavonoids in various clinical studies. Therefore, the application of nanotechnology to deliver flavonoids to tumor sites has received considerable attention in recent years.
  
  
  METHODS
  In this review, after a general review of the potential benefits of flavonoids in cancer therapy and several key factors affecting their bioavailability, the current efforts in improving the delivery efficacy of promising candidates that are particularly important in the human diet, namely quercetin, epigallocatechin-3-gallate (EGCG) and genistein were focused on. Finally, the challenges of developing flavonoid delivery systems that improve flavonoid bioavailability and their anticancer therapy potentials were summarized.
  
  
  CONCLUSIONS
  The design of suitable molecular carriers for flavonoids is an area of research that is in rapid progress. A large number of unheeded promising favonoids are suffering from poor in vivo parameters, their potential benefits deserves further research. Furthermore, more effort should be placed on developing active targeting systems, evaluating the efficacy and toxicity of novel flavonoid delivery systems through small and large scale clinical trials.
authors.affiliation: Assistant Professor, University of Macau, Institute of Chinese Medical Sciences, State Key Laboratory of Quality Research in Chinese Medicine , Av. Padre Tomas Pereira S.J, Taipa, Macau, 999078 , China mwchen@umac.mo.
authors.forename: Shengpeng
authors.initials: S
authors.lastname: Wang
authors.forename: Jinming
authors.initials: J
authors.lastname: Zhang
authors.forename: Meiwan
authors.initials: M
authors.lastname: Chen
authors.forename: Yitao
authors.initials: Y
authors.lastname: Wang
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000008:administration & dosage*; D001682:Biological Availability; D002392:Catechin / Q000008:administration & dosage / Q000031:analogs & derivatives; D016503:Drug Delivery Systems; D005419:Flavonoids / Q000008:administration & dosage*; D019833:Genistein / Q000008:administration & dosage; D006801:Humans; D036103:Nanotechnology; D009369:Neoplasms / Q000188:drug therapy*; D011794:Quercetin / Q000008:administration & dosage
chemical_list: D000970:Antineoplastic Agents; D005419:Flavonoids; D002392:Catechin; D011794:Quercetin; C045651:epigallocatechin gallate; D019833:Genistein; C041477:3-hydroxyflavone