Comparative Evaluation of the Cytotoxicity of Glyphosate-Based Herbicides and Glycine in L929 and Caco2 Cells.

Francesca Truzzi,Fiorella Belpoggi,Paul T J Scheepers,Giovanni Dinelli,Federica Gnudi,Ellen K Silbergeld,Daniele Mandrioli

doi:10.3389/fpubh.2021.643898

Abstract

Introduction: Glyphosate, an amino acid analog of glycine, is the most widely applied organophosphate pesticide worldwide and it is an active ingredient of all glyphosate-based herbicides (GBHs), including the formulation “Roundup. ” While glycine is an essential amino acid generally recognized safe, both epidemiological and toxicological in vivo and in vitro studies available in literature report conflicting findings on the toxicity of GBHs. In our earlier in vivo studies in Sprague–Dawley rats we observed that exposure to GBHs at doses of glyphosate of 1.75 mg/kg bw/day, induced different toxic effects relating to sexual development, endocrine system, and the alteration of the intestinal microbiome. In the present work, we aimed to comparatively test in in vitro models the cytotoxicity of glycine and GBHs.Methods: We tested the cytotoxic effects of glycine, glyphosate, and its formulation Roundup Bioflow at different doses using MTT and Trypan Blue assays in human Caco2 and murine L929 cell lines.Results: Statistically significant dose-related cytotoxic effects were observed in MTT and Trypan Blue assays in murine (L929) and human (Caco2) cells treated with glyphosate or Roundup Bioflow. No cytotoxic effects were observed for glycine. In L929, Roundup Bioflow treatment showed a mean IC50 value that was significantly lower than glyphosate in both MTT and Trypan Blue assays. In Caco2, Roundup Bioflow treatment showed a mean IC50 value that was significantly lower than glyphosate in the MTT assays, while a comparable IC50 was observed for glyphosate and Roundup Bioflow in Trypan Blue assays. IC50 for glycine could not be estimated because of the lack of cytotoxic effects of the substance.Conclusion: Glyphosate and its formulation Roundup Bioflow, but not glycine, caused dose-related cytotoxic effects in in vitro human and murine models (Caco2 and L929). Our results showed that glycine and its analog glyphosate presented different cytotoxicity profiles. Glyphosate and Roundup Bioflow demonstrate cytotoxicity similar to other organophosphate pesticides (malathion, diazinon, and chlorpyriphos).

Highlights

Glyphosate, an amino acid analog of glycine, is the most widely applied organophosphate pesticide worldwide and it is an active ingredient of all glyphosate-based herbicides (GBHs), including the formulation “Roundup. ” While glycine is an essential amino acid generally recognized safe, both epidemiological and toxicological in vivo and in vitro studies available in literature report conflicting findings on the toxicity of GBHs
The cytotoxic effects were observed at doses that are lower than the current EU NOAEL (50 mg/Kg bw)
Different organophosphates other than glyphosate proved had similar effects in different in vitro models: in particular malathion exposure induced dose-dependent cytotoxic effects in MTT assays performed on HepG2 human liver cell line [47], diazinon exposure induced dose-dependent cytotoxic effects in MTT assays performed on HCT116 human intestinal cell line [48], chlorpyrifos induced dose-and time-dependent cytotoxic effects in MTT assays performed on SH-SY5Y human neural cell line [49]

Summary

Introduction

Glyphosate, an amino acid analog of glycine, is the most widely applied organophosphate pesticide worldwide and it is an active ingredient of all glyphosate-based herbicides (GBHs), including the formulation “Roundup. ” While glycine is an essential amino acid generally recognized safe, both epidemiological and toxicological in vivo and in vitro studies available in literature report conflicting findings on the toxicity of GBHs. We aimed to comparatively test in in vitro models the cytotoxicity of glycine and GBHs. Glyphosate [IUPAC chemical name N-(phosphonomethyl)glycine], an amino acid analog of glycine, is the most widely applied organophosphate pesticide worldwide and it is an active ingredient of all glyphosate-based herbicides (GBHs), including in the formulation “Roundup” [1, 2]. Glyphosate [IUPAC chemical name N-(phosphonomethyl)glycine], an amino acid analog of glycine, is the most widely applied organophosphate pesticide worldwide and it is an active ingredient of all glyphosate-based herbicides (GBHs), including in the formulation “Roundup” [1, 2] It is mainly marketed as a broad-spectrum systemic herbicide and crop desiccant [3]. Glycine is very rapidly absorbed along the gastrointestinal tract via special carrier systems and transported via the portal vein into the liver and distributed within the whole body since it is involved in the body’s production of haem, DNA, phospholipids, and collagen [19]

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