Reduction of chrysotile asbestos-induced genotoxicity in human peripheral blood lymphocytes by garlic extract

Our plain-English summary of Reduction of chrysotile asbestos-induced genotoxicity in human peripheral blood lymphocytes by garlic extract, by K. Bhattacharya, S. Yadava, T. Papp, et al (Toxicology Letters, 2004).

The study

• Authors: K. Bhattacharya, S. Yadava, T. Papp, D. Schiffmann, Q. Rahman
• Journal: Toxicology Letters
• Published: 2004;153(3):327-32
• Cited by: 10 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Asbestos fibers are well known environmental carcinogen, however, the underlying mechanisms of their action have still not clearly been identified. Asbestos is capable of depleting glutathione and generating reactive oxygen species (ROS), which are important mediators of damage in biological system. Asbestos-induced mutagenecity, may be mediated by the generation. It is known that a number of scavengers and antioxidants attenuate asbestos-induced ROS release. Furthermore, it is known that garlic, contains numerous sulfur compounds and glutathione precursors which act as antioxidants and also demonstrate anticarcinogenic properties. The aim of this study was to investigate whether garlic extract has any influence on asbestos-mediated genotoxicity. As an assay system, we applied the micronucleus assay, sister chromatid exchanges, and chromosomal aberrations with human peripheral blood lymphocytes, which has already been used to analyze the genotoxicity of asbestos fibers. Our results indicate that garlic extract, when administered to the lymphocytes cell culture simultaneously with chrysotile reduced the rates of micronucleus formation, sister chromatid exchanges, and chromosomal aberrations significantly. We conclude that garlic extract may be an efficient, physiologically tolerable quencher of asbestos-mediated genotoxicity.

In plain English

This was a laboratory experiment on human blood cells, not a study of exposed people. The authors took blood from healthy non-smoking volunteers (how many is not stated), grew the white blood cells (lymphocytes) in culture, and exposed them to Rhodesian chrysotile asbestos (UICC standard), with and without fresh garlic extract. They measured three signs of genetic damage: micronuclei, chromosomal aberrations and sister chromatid exchanges. Chrysotile alone raised all three. For example, micronuclei averaged 20 per 1000 cells. Adding garlic extract at 2 µl/ml lowered micronuclei to an average of 12 per 1000 cells and lowered chromosome breaks and fragments. The authors reported these drops as statistically significant. They also reported a drop in sister chromatid exchanges, but the averages they printed (5.66 with chrysotile alone, 8.65 with garlic added) do not show one. Lower garlic doses gave no protection. At 5 µl/ml, too few dividing cells were found for the sister chromatid exchange test. The authors concluded that garlic extract can reduce chrysotile-induced genetic damage in this setting and that studies in living organisms are needed. They did not analyze the garlic's chemical makeup.

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: In vitro laboratory experiment: cultured human peripheral blood lymphocytes exposed to chrysotile with or without fresh garlic extract, tested with the micronucleus assay, sister chromatid exchange and chromosomal aberration tests
• Who was studied: Lymphocytes cultured from blood of healthy non-smoking volunteers. The number of donors, the place and the dates of collection are not stated. Scoring: 2000 binucleated cells per point for micronuclei, 150 metaphases per sample for sister chromatid exchanges (experiment repeated three times), 60 metaphases per sample for chromosomal aberrations.
• Exposure: Rhodesian chrysotile (UICC standard), average fiber diameter 0.10 µm and length 2.28 µm, about 5% of fibers 5 µm or longer, at 50 µg/ml for 72 hours. Fresh garlic extract was added after the fibers at 2 µl/ml and 5 µl/ml; lower concentrations were also tried.
• Main results:
  • Chrysotile alone (50 µg/ml) produced significantly more micronuclei than control: mean 20 ± 2.16 per 1000 cells, P < 0.01.
  • Chrysotile alone raised chromatid aberrations (mean gaps 1.51 ± 0.56, breaks 2.3 ± 0.56, fragments 2.56 ± 0.7, P < 0.05). In the table, control values were 0.08, 0.11 and 0.10.
  • Chrysotile alone raised isochromatid aberrations (mean gaps 1.3 ± 0.53, breaks 2.11 ± 0.55, fragments 1.7 ± 0.97, P < 0.05).
  • Chrysotile alone produced significant sister chromatid exchange formation: mean 5.66 ± 1.24, P < 0.01.
  • With chrysotile plus 2 µl/ml garlic extract, micronuclei fell to a mean of 12 ± 1.63 per 1000 cells (P < 0.001) compared with chrysotile alone.
  • With chrysotile plus 2 µl/ml garlic extract, isochromatid breaks fell to 0.18 ± 0.39 and fragments to 0.91 ± 0.67 (P < 0.05). Chromatid breaks were 0.21 ± 0.41 and fragments 0.55 ± 0.5.
  • The authors described a significant reduction in sister chromatid exchanges with chrysotile plus 2 µl/ml garlic extract, but the mean they printed (8.65 ± 1.24, P < 0.001) is higher than the chrysotile-alone mean of 5.66.
  • Garlic extract concentrations below 2 µl/ml gave no protection (data not shown).
  • At 5 µl/ml and above, the authors reported no significant reduction in micronuclei or chromosomal aberrations. Too few dividing cells were found for the sister chromatid exchange test, which the authors attributed to cytotoxicity.
• The authors' conclusion: The authors concluded that garlic has the capability to reduce chrysotile asbestos-induced genotoxicity, possibly by interacting with the antioxidant enzyme system and decreasing reactive oxygen species. They called 2 µl/ml the 'optimum dose' in vitro and said further in vivo studies are needed.
• Limitations the authors state:
  • The chemical constituents of the fresh garlic bulbs were not determined.
  • The mechanism of garlic's effect is not fully clear, and further in vivo studies are needed.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Chrysotile.

Medical terms in this study, explained in our Lexicon: Chrysotile, Genotoxicity, Glutathione (GSH), Reactive Oxygen Species (ROS).

Related studies

• Chromosomal aberrations induced by chrysotile and crocidolite in human lymphocytes in vitro — F. Valerio, M. de Ferrari, et al. (1983)
• Garlic attenuates chrysotile-mediated pulmonary toxicity in rats by altering the phase I and phase II drug metabolizing enzyme system — M. Ameen, M.S. Musthapa, et al. (2003)
• Cytotoxic and genotoxic effects of calcium silicates on human lymphocytes in vitro — M. Aslam, N. Fatima, et al. (1993)
• Smoking enhances asbestos-induced genotoxicity, relative involvement of chromosome 1: a study using multicolor FISH with tandem labeling — M. Lohani, E. Dopp, et al. (2002)
• Diallylsulfide attenuates asbestos-induced genotoxicity — M. Lohani, S. Yadav, et al. (2003)
• Investigation of micronucleus frequencies in lymphocytes of inhabitants environmentally exposed to chrysotile asbestos — H. Dönmez-Altuntas, M. Baran, et al. (2007)

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