Influence of metal ions on flavonoid protection against asbestos-induced cell injury

Our plain-English summary of Influence of metal ions on flavonoid protection against asbestos-induced cell injury, by V.A. Kostyuk, A.I. Potapovich, E.N. Vladykovskaya, et al (Archives of Biochemistry and Biophysics, 2001).

The study

• Authors: V.A. Kostyuk, A.I. Potapovich, E.N. Vladykovskaya, L.G. Korkina, I.B. Afanas'ev
• Journal: Archives of Biochemistry and Biophysics
• Published: 2001;385(1):129-37
• Cited by: 55 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Influence of metal ions (Fe2+, Fe3+, Cu2+, Zn2+) on the protective effect of rutin, dihydroquercetin, and green tea epicatechins against in vitro asbestos-induced cell injury was studied. Metals have been found to increase the capacity of rutin and dihydroquercetin to protect peritoneal macrophages against chrysotile asbestos-induced injury. The data presented here show that this effect is due to the formation of flavonoid metal complexes, which turned out to be more effective radical scavengers than uncomplexed flavonoids. At the same time epicatechins and their metal complexes have similar antiradical properties and protective capacities against the asbestos induced injury of macrophages. Metal complexes of all flavonoids were found to be considerably more potent than parent flavonoids in protecting red blood cells against asbestos-induced injury. It was also found that the metal complexes of all flavonoids were absorbed by chrysotile asbestos fibers considerably better than uncomplexed compounds and probably for this reason flavonoid metal complexes have better protective properties against asbestos induced hemolysis. Thus, the results of the present study show that flavonoid metal complexes may be effective therapy for the inflammatory response associated with the inhalation of asbestos fiber. The advantage of their application could be the strong increase in ROS scavenging by flavonoids and finally a better cell protection under the conditions of cellular oxidative stress.

In plain English

This was a laboratory study of cells and chemical test systems, not people. The authors tested whether metal ions (two forms of iron, copper and zinc) changed how well four plant compounds called flavonoids (rutin, dihydroquercetin and two green tea catechins) protected cells from damage by chrysotile asbestos fibers from Tuva, Russia. They used immune cells (peritoneal macrophages) taken from rats and red blood cells. Metal complexes of rutin and dihydroquercetin scavenged reactive oxygen molecules better than the plain compounds and protected macrophages better. For the tea catechins, metal binding made no difference to macrophage protection. In the red blood cell tests, all the metal complexes protected cells much better than the plain compounds. Asbestos alone damaged 51.8 percent of red cells, compared with 2.3 percent when a copper-rutin complex was added. The metal complexes also stuck to the fibers more. The authors concluded that flavonoid metal complexes may be effective therapy for asbestos-related inflammation, but they noted they had no evidence that swallowed complexes reach the blood unchanged.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Laboratory (in vitro) experiments using isolated animal cells and cell-free chemical assays
• Who was studied: Peritoneal macrophages from Wistar rats; red blood cells (described as rat blood in the methods and as human red blood cells in the results); rat liver microsomes. No numbers of animals are given.
• Exposure: Natural chrysotile asbestos fibers from Tuva, Russia, added to cell suspensions. The cells were also treated with rutin, dihydroquercetin, epigallocatechin gallate (EGCG) and epicatechin gallate (ECG), alone or combined 1 to 1 with ferrous iron, ferric iron, copper or zinc ions.
• Main results:
  • In the chemical tests, metal complexes of dihydroquercetin and rutin were more potent radical scavengers than the plain compounds.
  • In rat macrophages, metal complexes of rutin and dihydroquercetin protected against asbestos-induced injury better than the plain compounds.
  • In macrophages, the tea catechins and their metal complexes protected equally well.
  • In red blood cells, the plain compounds differed: rutin and ECG protected partially, and dihydroquercetin did not protect. All metal complexes were very effective.
  • Red cell destruction (hemolysis) was 51.8 plus or minus 5.3 percent with asbestos alone, 2.3 plus or minus 3.8 percent with asbestos plus a copper-rutin complex, and 1.1 plus or minus 0.6 percent in controls without asbestos (mean of 4 to 5 tests).
  • Adding EDTA, which removes metal ions, completely suppressed the protection that fiber-bound complexes gave red blood cells. Hemolysis was then 42.5 and 43.5 percent.
  • All the flavonoids stuck to chrysotile fibers, and metal ions increased this binding. Without metal, binding was 7 (rutin), 12 (dihydroquercetin), 10 (EGCG) and 16 (ECG) nmol per mg of fiber. With ferrous iron it was 20, 27, 34 and 42 nmol per mg (p less than 0.05 compared with the plain compounds).
• The authors' conclusion: The authors concluded that, in vitro, metal-flavonoid complexes (especially those of rutin and dihydroquercetin) were more effective radical scavengers and inhibitors of asbestos-induced cell injury than the plain compounds. They suggested such complexes may be effective therapy for the inflammatory response associated with inhaling asbestos fiber.
• Limitations the authors state:
  • The authors stated they had no experimental evidence that swallowed flavonoid-metal complexes reach the bloodstream unchanged.
  • The authors noted that some findings did not fit their proposed explanation: zinc, which cannot transfer electrons, still enhanced rutin, and tea catechins acted the same with or without metals.

Topics

Medical terms in this study, explained in our Lexicon: Macrophage, Chrysotile, Oxidative Stress.

Related studies

• Antiradical and chelating effects in flavonoid protection against silica-induced cell injury — V.A. Kostyuk, A.I. Potapovich (1998)
• Protective effect of natural flavonoids on rat peritoneal macrophages injury caused by asbestos fibers — V.A. Kostyuk, A.I. Potapovich, et al. (1996)
• Comparative study of antioxidant properties and cytoprotective activity of flavonoids — A.I. Potapovich, V.A. Kostyuk (2003)
• The role of iron in Libby amphibole-induced acute lung injury and inflammation — J.H. Shannahan, A.J. Ghio, et al. (2011)
• Chrysotile inhibits glutathione-dependent protection against the onset of lipid peroxidation in rat lung microsomes — J.M. Arif, I. Ahmad, et al. (1996)
• In vitro genotoxicity of asbestos substitutes induced by coupled stimulation of dissolved high-valence ions and oxide radicals — T. Huo, F. Dong, et al. (2018)

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