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Planta Med 2002; 68(5): 445-448
DOI: 10.1055/s-2002-32073
Original Paper
Analysis
© Georg Thieme Verlag Stuttgart · New York

Interference of Plant Extracts, Phytoestrogens and Antioxidants with the MTT Tetrazolium Assay

Regina Bruggisser1 , Katrin von Daeniken1 , Gernot Jundt2 , Willi Schaffner1 , Heide Tullberg-Reinert2
  • 1Institute of Pharmaceutical Biology, University of Basel, Basel, Switzerland
  • 2Laboratory of Experimental Osteology at the Institute of Pathology, Kantonsspital Basel/University Clinics, Basel, Switzerland
Further Information

Publication History

July 31, 2001

October 21, 2001

Publication Date:
07 June 2002 (online)

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Abstract

The MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay is a widely used screening method to measure cell viability and proliferation. When testing the effects of kaempferol on breast cancer cell number (crystal violet staining) and viability (MTT tetrazolium assay) conflicting results were obtained. Cell number decreased but MTT formazan formation increased, suggesting a direct interaction of kaempferol with the MTT tetrazolium reduction. Direct reductive potential was observed in a cell-free system for the presumptive phytoestrogens kaempferol and resveratrol, and extracts of Hypericum perforatum L. and Cimicifuga racemosa L. All agents led to instantaneous dark blue formazan formation in the absence of cells. Additionally, antioxidants such as ascorbic acid, vitamin E and N-acetylcysteine interfered with the MTT tetrazolium assay. When MCF7 and HS578 cells treated with kaempferol were washed before addition of MTT tetrazolium, the direct reduction of dye was reduced significantly. These results indicate that the MTT tetrazolium assay may lead to false positive results when testing natural compounds with intrinsic reductive potential.

Abbreviations

ATCC:American type culture collection

CV:Crystal violet

FCS:Fetal calf serum

MTT:3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium
bromide

O.D.:Optical density

Key words

MTT tetrazolium assay - phytoestrogens - plant extracts - antioxidants

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Heide Tullberg-Reinert, PhD

Laboratory of Experimental Osteology

Kantonsspital Basel/University Clinics

Schönbeinstrasse 40

4003 Basel, Switzerland

Email: htullberg@uhbs.ch

Fax: + 41 61 265 31 94

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