XXII. BIOCHEMICKÝ ZJAZD - Jesseniova lekárska fakulta

Posters
101.
INHIBITOry effECT of naTUral flavONOIDS ON EQUINE LIver
GLUTatHIONE s-traNSferaSE
Iva Boušová, Zuzana Průchová, Lucie Trnková and Jaroslav Dršata
Department of Biochemical Sciences, Charles University in Prague, Faculty of
Pharmacy, Hradec Králové
Mammalian glutathione S-transferases (GST, EC 2.5.1.18), group of intracellular enzymes
involved in detoxification of xenobiotics, belong to the most abundant cytosolic proteins.
They catalyze conjugation of the thiol group of the glutathione (GSH) to electrophilic xenobiotics,
and thereby defend cells against the mutagenic, carcinogenic, and toxic effects of
these compounds. Several classes of GST isozymes differing in substrate specificity exist.
Flavonoids are a group of polyphenolic compounds that are widely distributed in plant
kingdom. They are known to possess antioxidant, anti-radical, antiviral, antibacterial,
anti-inflammatory, and vasodilatory activity. Besides positive acting, flavonoids exert
also pro-oxidative effects and are able to inhibit various enzymes (e.g. cyclooxygenase
and glutathione peroxidase). We suppose that dietary flavonoids may inhibit GST and
thus influence detoxification of xenobiotics.
GST was incubated in the presence or absence of flavonoids (0-100 µM). Then its activity
was measured using common spectrophotometric assay with 1chloro-2,4-dinitrobenzene
adapted to 96-well plates. Inhibitory effect of studied flavonoids was characterized by IC 50
values. The most pronounced inhibition was found in the case of gallocatechin gallate (IC50
= 1.26 µM), which is the major polyphenolic constituent in the green tea. The obtained
results indicated that GST can be a potential target for inhibitory effect of flavonoids.
Acknowledgments: This study was supported by the Czech Science Foundation (GAČR,
grant No. 524/09/P121).
226 XXII. Biochemistry Congress, Martin