Planta Med 2005; 71(12): 1118-1122
DOI: 10.1055/s-2005-873174
Original Paper
Pharmacology
© Georg Thieme Verlag KG Stuttgart · New York

The Action of Quercetin on the Mitochondrial NADH to NAD+ Ratio in the Isolated Perfused Rat Liver

Gisele D. Buss1 , Jorgete Constantin1 , Leonardo C. N. de Lima1 , Graziele R. Teodoro1 , Jurandir F. Comar1 , Emy L. Ishii-Iwamoto1 , Adelar Bracht1
  • 1Laboratory of Liver Metabolism, University of Maringá, 87020900 Maringá, Brazil
Further Information

Publication History

Received: February 10, 2005

Accepted: June 10, 2005

Publication Date:
10 November 2005 (online)

Abstract

It has been suggested that active forms of quercetin (o-semiquinones) are able to oxidize NADH in mammalian cells. The purpose of this study was to investigate this proposition by measuring the β-hydroxybutyrate to acetoacetate ratio as an indicator of the mitochondrial NADH/NAD+ redox ratio in the isolated perfused rat liver. The NADH to NAD+ ratio was reduced by quercetin; half-maximal reduction occurred at a concentration of 32.6 μM. Additionally, quercetin (25 to 300 μM) stimulated the Krebs cycle (14CO2 production) and inhibited oxygen uptake (50 to 300 μM). Low quercetin concentrations (25 μM) stimulated oxygen uptake. The results of the present work confirm the hypothesis that quercetin is able to participate in the oxidation of NADH in mammalian cells, shifting the cellular conditions to a more oxidized state (prooxidant activity). Stimulation of the Krebs cycle was probably caused by the increased NAD+ availability whereas the decreased NADH availability and the inhibition of mitochondrial energy transduction could be the main causes for oxygen uptake inhibition.

References

Adelar Bracht

Laboratory of Liver Metabolism

Department of Biochemistry

University of Maringá

87020900 Maringá

Brazil

Fax: +55-44-3261-4896

Email: adebracht@uol.com.br