Elsevier

Methods in Enzymology

Volume 105, 1984, Pages 523-532
Methods in Enzymology

[69] Exacerbation of superoxide radical formation by Paraquat

https://doi.org/10.1016/S0076-6879(84)05072-2Get rights and content

Publisher Summary

Paraquat, also known as methyl viologen, is the active ingredient of many commercially available broad-spectrum herbicides. Paraquat seems to be universally toxic both in prokaryotes and eukaryotes, and incidents of fatal paraquat poisonings have been reported in man and animals. Crude cell-free extracts from plants, animals, and bacterial origins have been shown to reduce PQ2+ to PQ·+in the presence of nicotinamide adenine dinucleotide phosphate (NADPH) or an NADPH-generating system (i.e., glucose-6-phosphate, glucose-6-phosphate dehydrogenase, and NADP+). The enzyme that reduces PQ2+ is a diaphorase-like enzyme usually present in the cytoplasm and specific for NADPH. Paraquat is readily reduced by a single electron to a stable but dioxygen-sensitive monocation radical (PQ·+). The reaction between the paraquat radical and dioxygen (O2) generates the true toxic species, the superoxide radical (O2-), and subsequently hydrogen peroxide (H2O2). Hydroxyl radicals (OH·) may also be generated because of secondary interactions between O2- and H2O2. This chapter presents methods for measuring and identifying the partially reduced oxygen species generated during the reaction of PQ·+ and O2.

References (21)

  • J.A. Farrington et al.

    Biochim. Biophys. Acta

    (1973)
  • R.C. Baldwin et al.

    Toxicol. Appl. Pharmacol.

    (1975)
  • H.M. Hassan et al.

    J. Biol. Chem.

    (1978)
  • R. Schmid

    FEBS Lett.

    (1975)
  • A.N. Saprin et al.

    Arch. Biochem. Biophys.

    (1977)
  • H.M. Hassan et al.

    J. Biol. Chem.

    (1977)
  • H.M. Hassan et al.

    Arch. Biochem. Biophys.

    (1979)
  • H.J. Vogel et al.

    J. Biol. Chem.

    (1956)
  • H.M. Hassan et al.

    J. Biol. Chem.

    (1979)
  • H.M. Hassan et al.
There are more references available in the full text version of this article.

Cited by (54)

  • Selective mitochondrial superoxide generation in vivo is cardioprotective through hormesis

    2019, Free Radical Biology and Medicine
    Citation Excerpt :

    To investigate the consequences of a primary increase in ROS specifically within the mitochondrial compartment, we used the mitochondria-targeted compound MitoParaquat (MitoPQ) [31]. MitoPQ was designed based upon the conjugation of a paraquat moiety (1,1’-dimethyl-4,4’-bipyridinium dichloride) [32] with the mitochondria targeting triphenylphosphonium group. At the flavin site of complex I in the electron transport chain, MitoPQ accepts an electron to generate a radical monocation that reacts rapidly with oxygen to specifically generate superoxide, which is the proximal ROS species produced endogenously [33].

  • Interaction of methyl viologen-induced chloroplast and mitochondrial signalling in Arabidopsis

    2019, Free Radical Biology and Medicine
    Citation Excerpt :

    Paraquat is the common name of the herbicide methyl viologen (MV; N,-N′-dimethyl-4,-4′-bipyridinium dichloride), which acts in the production of ROS via a light dependent mechanism. In chloroplasts MV competes with ferredoxin for electrons on the acceptor side of photosystem I (PSI) [3,4] and forms the MV cation radical, which reacts instantly with O2 to form superoxide (O2. -) [5]. O2. -

  • Oxidative stress elicited by insecticides: A role for the adipokinetic hormone

    2011, General and Comparative Endocrinology
    Citation Excerpt :

    Recently it has been proven that AKHs [29,50], ecdysteroids [34], juvenile hormone [25] and glucagon [1] play this role in insects. Application of the oxidative stressors such as paraquat [21], Gallanthus nivalis agglutinin and Bacillus thuringiensis toxin [29], and insecticides endosulfan and malathion (this study) elevates the titre of AKHs in haemolymph and depending on duration of the stressor incidence, also in the CNS. All those findings suggest that AKH might be involved in the activation of an antioxidant protection processes.

View all citing articles on Scopus

Paper Number 8792 of the Journal Series of the North Carolina Agricultural Research Service, Raleigh, NC 27650. The use of trade names in this publication does not imply endorsement by the North Carolina Agricultural Research Service of the products named, nor criticism of similar ones not mentioned.

View full text