Lipid Peroxidation Induced by Expandable Clay Minerals

Abstract

Small-sized environmental particles such as 2:1 phyllosilicates induce oxidative stress, a primary indicator of cell damage and toxicity. Herein, potential hazards of clay particle uptake are addressed. This paper reports that the content and distribution of structural Fe influence the ability of expandable clay minerals to induce lipid peroxidation (LP), a major indicator of oxidative stress, in biological matrices. Three smectite clays, hectorite (SHCa-1) and two nontronites (NAu-1) and (NAu-2) containing varying total content and coordination environment of structural Fe, were selected. Screening and monitoring of LP was conducted using a thiobarbituric acid reactive substances (TBARS) assay. The higher content of TBARS in nontronites than that in SHCa-1 suspensions was explained because structural Fe contributes to LP. The observed lack of correlation between TBARS content and the extent of Fe dissolution indicated that the formation of TBARS is surface controlled. Results showing a high TBARS content in SHCa-1 but not in nontronite supematant solutions was explained because the former contains distinct, soluble chemical component(s) that could (i) induce LP by its (their) own right and (ii) whose chemical affinity for organic ligands used as inhibitors is weak. Clays serve as stronger inductors than 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH) but are much weaker than FeSO4. The outcome of this work shows that LP is clay surface-controlled and dependent on clay structural composition.

Arsenic(III) methylation in betaine–nontronite clay–water suspensions under environmental conditions

“…Table 3 (top, 5th and 6th columns) show a higher extent of As(III) conversion in the presence of NAu-2 over NAu-1. These results agree well with reports on the higher reactivity of NAu-2 over NAu-1 as evidenced by their relative ability to induce lipid peroxidation, a major indicator of oxidative stress [34], for example. Existing structural differences between NAu-1 and NAu-2 are associated with the distribution of structural iron over the total structural iron content alone (35.21 and 37.85% Fe 2 O 3 , respectively; [3]).…”

Toxicological evaluation of clay minerals and derived nanocomposites: A review

“…Regarding oxidative stress biomarkers, Kibanova et al (2009) reported that nontronites induced higher LPO than hectorite in brain supernatant solutions exposed to up to 1000 ppm. Maisanaba et al (2014e), however, did not find any alteration in the LPO, SOD, GPx and GST activities in the liver and kidney of rats exposed for 90 days to a 40 mg/kg bw/d Mt-modified clay (Clay1), although the CAT activity, gene expression and protein abundance were increased in the kidney.…”

“…Several researchers have already evaluated the in vitro toxicological profiles of different clays and derived nanocomposites, concluding that the toxicity shown depends on various parameters, the most important of which were the modifiers used, the experimental model selected, the concentration range and the exposure times (Section 2). Regarding the in vivo assessments, although it has been recognized that the interaction of clays with organs may provoke health-deleterious consequences, to date, there is little mechanistic understanding of the physiological effects due to exposure to clays (Kibanova et al, 2009). Some studies performed in vivo can be found in the literature, and different results have been published (Section 3).…”

Oxidative stress inhibition and oxidant activity by fibrous clays

“…Lipids recovered from supernatants of rat brain homogenate were used. All incubations lasted 4 h [26,27]. The contents of TBARS in sepiolite or palygorskite dispersions were compared against negative controls ( Fig.…”