TY - JOUR
T1 - Structure and activity in assessing antioxidant activity in vitro and in vivo
T2 - a critical appraisal illustrated with the flavonoids
AU - Haenen, Guido R.M.M.
AU - Arts, Mariken J.T.J.
AU - Bast, Aalt
AU - Coleman, Micheal D.
PY - 2006/2
Y1 - 2006/2
N2 - Structure–activity relationships are indispensable to identify the most optimal antioxidants. The advantages of in vitro over in vivo experiments for obtaining these relationships are, that the structure is better defined in vitro, since less metabolism takes place. It is also the case that the concentration, a parameter that is directly linked to activity, is more accurately controlled. Moreover, the reactions that occur in vivo, including feed-back mechanisms, are often too multi-faceted and diverse to be compensated for during the assessment of a single structure–activity relationship. Pitfalls of in vitro antioxidant research include: (i) by definition, antioxidants are not stable and substantial amounts of oxidation products are formed and (ii) during the scavenging of reactive species, reaction products of the antioxidants accumulate. Another problem is that the maintenance of a defined concentration of antioxidants is subject to processes such as oxidation and the formation of reaction products during the actual antioxidant reaction, as well as the compartmentalization of the antioxidant and the reactive species in the in vitro test system. So determinations of in vitro structure-activity relationships are subject to many competing variables and they should always be evaluated critically. (c) 2005 Published by Elsevier B.V.
AB - Structure–activity relationships are indispensable to identify the most optimal antioxidants. The advantages of in vitro over in vivo experiments for obtaining these relationships are, that the structure is better defined in vitro, since less metabolism takes place. It is also the case that the concentration, a parameter that is directly linked to activity, is more accurately controlled. Moreover, the reactions that occur in vivo, including feed-back mechanisms, are often too multi-faceted and diverse to be compensated for during the assessment of a single structure–activity relationship. Pitfalls of in vitro antioxidant research include: (i) by definition, antioxidants are not stable and substantial amounts of oxidation products are formed and (ii) during the scavenging of reactive species, reaction products of the antioxidants accumulate. Another problem is that the maintenance of a defined concentration of antioxidants is subject to processes such as oxidation and the formation of reaction products during the actual antioxidant reaction, as well as the compartmentalization of the antioxidant and the reactive species in the in vitro test system. So determinations of in vitro structure-activity relationships are subject to many competing variables and they should always be evaluated critically. (c) 2005 Published by Elsevier B.V.
KW - activity
KW - antioxidant
KW - flavonoid
KW - stability
KW - structure
KW - toxicity
UR - http://www.scopus.com/inward/record.url?scp=31544477682&partnerID=8YFLogxK
U2 - 10.1016/j.etap.2005.07.010
DO - 10.1016/j.etap.2005.07.010
M3 - Article
SN - 1382-6689
VL - 21
SP - 191
EP - 198
JO - Environmental Toxicology and Pharmacology
JF - Environmental Toxicology and Pharmacology
IS - 2
ER -