Evidence for DNA-diquat interaction and cytotoxicity in in vitro rat cells

Abstract

Over 98% of sprayed insecticides and 95% of herbicides reach non-target species in air, soil, and water. Numerous studies have reported that pesticide residues can cause acute and chronic toxicity. Pesticide residues can be carcinogenic, mutagenic, and immunotoxic. There are actually too few studies that bridge the disciplines of chemobioanalysis and environmental toxicology. Here, we assessed the cytotoxicity of a bipyridilium herbicide diquat in rat adrenal pheochromocytoma cells (PC12). Our results show that diquat caused the decrease in cell viability with a lethal concentration 50 (LC 50 ) of 1.4 9 10 -5 mol/L. This cytotoxicity may result from diquat-induced apoptosis, characterized by nuclear fragmentation and chromatin condensation by Hoechst 33324 staining. To explore the possible mechanisms, the interaction between herbicide diquat and calf thymus DNA (ctDNA) was further investigated using fluorescence quenching. The detection of static quenching showed that diquat was linked with ctDNA by electrostatic interaction with a binding constant of 9.288 9 10 4 L/mol. This is the first study on the interaction of DNA with herbicide diquat by fluorometric method as well as on the evaluation of cytotoxicity by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and Hoechst staining. Given the widespread use of synthetic pesticides, the data would be valuable for the risk assessment of pesticide residues.

Intercalation binding of food antioxidant butylated hydroxyanisole to calf thymus DNA

“…DNA is quite often the main molecular target of chemicals, and many forms of cancer could be partly due to acute changes in DNA functions caused by harmful small molecules. Many studies regarding the interactions between DNA and harmful chemicals have been reported, such as pyriproxyfen [9], permethrin [10], clodinafoppropargyl [11], diquat [12], salbutamol [13], ractopamine [14], and heavy metal ions [15]. In recent years, some food additives such as dyes [16][17][18] and sweeteners [19,20] bound to DNA were also investigated.…”

Synthesis, Optical Properties, and DNA Interaction of New Diquats Based on Triazolopyridines and Triazoloquinolines

“…[13,14,17] Figure 10 shows the changes in fluorescence emmision spectra for compound L4 during titration with ct-DNA.O nly for diquats L3 and L4 was it possible to apply aS tern-Volmer relationship;t he value of the corresponding constant (K SV )w as higher for compound L3 (4.25 10 3 m À1 )t han for L4 (3.38 10 3 m À1 ), which can be attributed to the planarity of ligand L3 (Table 1). In all cases, an increase in absorption was observed between 200 and 300 nm owing to the intrinsic DNA absorbance in this region.…”

“…Molecular orbital calculations can be used to estimate 13 CNMR chemical shifts. Ab initio and DFT calculations of NMR shieldinga tv ery accurate levels of approximation are available in the literature.…”

“…Diquats L1 and L2 suffered quenchingo ft heir emission without any shiftingo ft he wavelength, whereas the spectra of compounds L3 and L4 displayed ah ypsochromics hift, aw ell known phenomena for intercalative compounds. [13,14,17] Figure 10 shows the changes in fluorescence emmision spectra for compound L4 during titration with ct-DNA.O nly for diquats L3 and L4 was it possible to apply aS tern-Volmer relationship;t he value of the corresponding constant (K SV )w as higher for compound L3 (4.25 10 3 m À1 )t han for L4 (3.38 10 3 m À1 ), which can be attributed to the planarity of ligand L3 (Table 1).…”

“…Diquat derivatives possess axial chirality,w hich results in two enantiomeric configurations: P (R a )a nd M (S a ). Althoughd iquat was reported to interact with DNA only through electrostatic interactions, [13] the incorporation of appropriate aromatic substituents can lead to intercalative binding modes. [12] Other derivatives without C 2 symmetry have also been described;for example, the dipyridiniumdihydrohelicenes described by Zysman-Colman in 2015, whicha dopt ahelicals tructure.…”