Spectroscopic Analysis of the Binding of Paraquat and Diquat Herbicides to Biosubstrates.

Francesca Macii,Stefania Giannarelli,Francesca Rita Bloise,Rebecca Detti,Tarita Biver

doi:10.3390/ijerph18052412

Francesca Macii, Stefania Giannarelli + Show 3 more

Open Access

https://doi.org/10.3390/ijerph18052412

Copy DOI

Abstract

The study of the interaction of persistent organic pollutants with biosubstrates helps to unravel the pathways for toxicity, however, few mechanistic data are present in the literature for these systems. We analyzed the binding of paraquat (PQ) and diquat (DQ) herbicides to natural calf thymus DNA and a DNA G-quadruplex by spectrophotometric titrations, ethidium bromide exchange tests, viscometry, and melting experiments. The interaction with bovine serum albumin (BSA) protein was studied spectrofluorimetrically at different temperatures. The retention of the targets on positive, negative, and neutral micellar aggregates and liposomes was analyzed by ultrafiltration experiments. Despite some favorable features, PQ and DQ only externally bind natural DNA and do not interact with DNA oligonucleotides. Both herbicides bind bovine serum albumin (BSA). PQ binds BSA mainly according to an electrostatics-driven process. However, ultrafiltration data also show that some hydrophobic contribution participates in the features of these systems. The practical problems related to unfavorable spectroscopic signals and inner filter effects are also discussed. Overall, both herbicides show a low affinity for nucleic acids and weak penetration into liposomes; in addition, the equilibrium constants values found for BSA system suggest optimal conditions for transport in the body.

Highlights

IntroductionPublisher’s Note: MDPI stays neutral with regard to jurisdictional claims in
Received: 10 December 2020Accepted: 22 February 2021Published: 2 March 2021
The optical properties of PQ and DQ molecules were characterized under physiological conditions (NaCl 0.1 M, NaCac 2.5 mM, pH 7.0)

Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in. Among the copious classes of pesticides, bipyridyl herbicides deserve high interest due to their widespread application: they are quaternary ammonium compounds ( known as “quats”) marketed as contact herbicides and desiccants [1]. 2 of 171) are major and diquat (DQ) molecules that are the focus of the current study [1].herbicides [1]

Methods

Results

Conclusion