Raport de cercetare - Lorentz JÄNTSCHI

quercetin, flavanone, hesperetin and naringenin) studied inhibited microsomal ECOD activity in the
following order: flavones > flavonols > flavanones, were mixed type inhibitors and had Ki in the
range of 0·17-4·5 μM. (±)-Catechin had no effect. 3. The double bond between C2 and C3 of the C
ring, the keto group and hydroxyl group of this ring in the flavonoids seem to play major roles in
inhibiting the ECOD activity. 4. The hydroxyl groups in the C5 and C7 positions of A ring in the
flavone and the hydroxyl group in the C3 position of C ring in the flavonol classes, respectively,
were important factors for the inhibition of the enzyme. 5. In a series of 3, 5, 7-trihydroxyflavones,
the hydroxyl group at the C4 in the B ring was also an important factor for the inhibition of ECOD
activity, but hydroxyl groups in other positions of the B ring had little effect on the inhibition. 6.
We conclude that all the flavonoids studied inhibit ECOD activity by interfering with the binding of
substrate to the active site and other site(s) of the enzyme and that their structural differences lead to
different binding affinities at the active site and possibly to binding at other site(s) of the enzyme
for the flavonoids.
Nr Articol
2 Structure-antioxidant Activity Relationships of Flavonoids: A Re-examination
Authors: M. Manuela Silva a; Marta R. Santos a; Gonçalo Caroço a; Rui Rocha a; Gonçalo
Justino a; Lurdes Mira
Affiliation: a Departamento de Química e Bioquímica, Faculdade de Ciências da Universidade de
Lisboa, 1749-016 Lisboa, Portugal.
DOI: 10.1080/1071576021000016472
Publication Frequency: 12 issues per year
Published in: Free Radical Research, Volume 36, Issue 11 2002 , pages 1219 - 1227
Subjects: Cell Biology; Molecular Biology;
Number of References: 45
Formats available: PDF (English)
Abstract
The antioxidant and prooxidant activities of flavonoids belonging to several classes were studied to
establish their structure-activity relationships against different oxidants. Special attention was paid
to the flavonoids quercetin (flavone), taxifolin (flavanone) and catechin (flavanol), which possess
different basic structures but the same hydroxylation pattern (3,5,7,3',4'-OH). It was found that
these three flavonoids exhibited comparable antioxidant activities against different oxidants leading
to the conclusion that the presence of ortho -catechol group (3',4'-OH) in the B-ring is determinant
for a high antioxidant capacity. The flavone kaempferol (3,5,7,4'-OH), however, in spite of bearing
no catechol group, also presents a high antioxidant activity against some oxidants. This fact can be
attributed to the presence of both 2,3-double bond and the 3-hydroxyl group, meaning that the basic
structure of flavonoids becomes important when the antioxidant activity of B-ring is small.
Keywords: Flavonoids; Antioxidant; Free Radicals; Structure-activity Relationships
Nr Articol
3 Fuzzy structure-activity relationships
Author: B. T. Luke
Affiliation: a SAIC-Frederick, Inc., Advanced Biomedical Computing Center, NCI Frederick,
P.O. Box B, Frederick, MD 21702, USA.
DOI: 10.1080/1062936021000058773
Publication Frequency: 8 issues per year
Published in: SAR and QSAR in Environmental Research, Volume 14, Issue 1 2003 , pages 41 - 57
Subjects: Applied & Industrial Chemistry; Chemistry; Environmental & Ecological Toxicology;
Environmental Sciences; History & Philosophy of Mathematics;
Abstract
While quantitative structure-activity relationships attempt to predict the numerical value of the
activities, it is found that statistically good predictors do not always do a good job of qualitatively
determining the activity. This study shows how Fuzzy classifiers can be used to generate Fuzzy
structure-activity relationships which can more accurately determine whether or not a compound
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