title: New delivery systems to improve the bioavailability of resveratrol.
abstract: BACKGROUND
  Resveratrol (RSV) has been one of the most extensively studied polyphenols in the last 10 years, owing to its numerous and potent therapeutic activities, namely its high antioxidant properties. However, RSV's bioavailability is compromised by its physicochemical properties, such as low stability, increased oxidation on heat and light exposure, low water solubility and also its high hepatic uptake. Moreover, results obtained in human pharmacokinetic studies have shown a low amount of intact RSV in the systemic circulation, which does not justify its therapeutic activities, raising doubts about RSV's potential. RSV is already available as a nutritional supplement, although its translation to the clinic is not straightforward, owing to the lack of clinical data.
  
  
  METHODS
  In this review, formulations that are being used for delivery of RSV are discussed. New delivery systems are presented as valid alternatives to circumvent the limitations of the physicochemical characteristics and pharmacokinetics of RSV. In this way, they are compared with classical formulations with regard to improving RSV protection and bioavailability.
  
  
  CONCLUSIONS
  Despite promising results in preclinical settings, the applicability of RSV to humans has met with only limited success, largely owing to its inefficient systemic delivery and consequently its low bioavailability. To achieve an optimal response of RSV, new strategies are still required to enhance its bioavailability and reduce its perceived toxicity.
authors.affiliation: Centro de Estudos Farmacêuticos, Faculty of Pharmacy, University of Coimbra, Pólo das Ciências da Saúde, Azinhaga de Santa Comba, Coimbra, Portugal.
authors.forename: Ana Cláudia
authors.initials: AC
authors.lastname: Santos
authors.forename: Francisco
authors.initials: F
authors.lastname: Veiga
authors.forename: António J
authors.initials: AJ
authors.lastname: Ribeiro
mesh_terms: D000975:Antioxidants / Q000008:administration & dosage* / Q000493:pharmacokinetics*; D001682:Biological Availability; D002626:Chemistry, Pharmaceutical; D006801:Humans; D000077185:Resveratrol; D013267:Stilbenes / Q000008:administration & dosage* / Q000493:pharmacokinetics*
chemical_list: D000975:Antioxidants; D013267:Stilbenes; D000077185:Resveratrol