Glyphosate has remained the leading herbicide on the global market to date, despite the continuous debate between consumers, scientific community, and regulatory agencies over its carcinogenicity, genotoxicity, environmental persistence, and the role in the development of neurodegenerative disorders. Chemically, glyphosate belongs to a large family of organophosphorus pesticides, which exert a neurotoxic effect by inhibiting acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), enzymes of the cholinergic system essential for maintaining neurotransmission. Although research shows that glyphosate is a weak cholinesterase inhibitor in fish and mammals compared to other OP compounds, no conclusive data exist concerning the inhibition of human AChE and BChE. In our study we analysed its inhibitory potency on human AChE and BChE, by establishing its IC50 and reversible inhibition in terms of dissociation inhibition constants. Glyphosate concentration of 40 mmol/L caused near total inhibition of enzyme activity (approx. 10 % activity remaining). Inhibition dissociation constants (K i) of glyphosate-AChE and -BChE complexes were 28.4±2.7 mmol/L and 19.3±1.8 mmol/L, respectively. In conclusion, glyphosate shows a slight binding preference for BChE but exhibits inhibition only in a high concentration range. Our results are in line with studies reporting that its neurotoxic effect is not primarily linked to the cholinergic system.
Glifosat je vodeći herbicid na današnjem svjetskom tržištu, unatoč neprestanim raspravama između potrošača, znanstvene zajednice i regulatornih agencija o njegovoj kancerogenosti, genotoksičnosti, postojanosti u okolišu i utjecaju na razvoj neurodegenerativnih bolesti. Kemijski gledano, glifosat pripada velikoj obitelji pesticida, organofosfornim spojevima (OP) koji imaju neurotoksični učinak inhibirajući acetilkolinesterazu (AChE) i butirilkolinesterazu (BChE), esencijalne enzime kolinergičnoga sustava koji održava proces prijenosa živčanih impulsa. Iako su različita istraživanja pokazala da je glifosat slab inhibitor kolinesteraza u riba, sisavaca i ljudi u odnosu na druge organofosforne spojeve, još uvijek ne postoje konačni podatci o njegovoj inhibiciji ljudske AChE i BChE. U ovoj smo studiji analizirali inhibitorni potencijal za ljudsku AChE i BChE, procijenili IC50 vrijednosti i utvrdili reverzibilnu inhibiciju pomoću vrijednosti konstanti disocijacije inhibitora. Glifosat je gotovo u cijelosti inhibirao aktivnost enzima pri 40 mmol/L koncentraciji (preostalo je otprilike 10 % enzimske aktivnosti). Konstante disocijacije (K i) kompleksa glifosat-AChE i -BChE iznose 28.4±2.7 mmol/L, odnosno 19.3±1.8 mmol/L. Zaključno, glifosat iskazuje malu sklonost za vezanje BChE, no pokazuje inhibiciju u rasponu visokih koncentracija. Rezultati ovoga istraživanja podupiru rezultate postojećih studija prema kojima neurotoksični učinak glifosata nije primarno vezan za kolinergični sustav.

The aim of this study was to investigate oxidative stress induced by perfluorooctanoic acid (PFOA) in the brain and liver tissues of Balb/c mice as well as protective effects of taurine and coenzyme Q10 (CoQ10) in both organs. For this purpose, animals were treated with PFOA (15 and 30 mg/kg) orally and their lipid peroxidation, total glutathione levels (GSH), and antioxidant enzyme activities measured and both tissues analysed for histopathological changes. Our results showed a dose-dependent decrease in body weight and increase in relative brain and liver weights, PFOA-induced lipid peroxidation and reduced glutathione peroxidase (GPx) activity in the brain tissue, and changes in GSH levels, GPx, superoxide dismutase (Cu-Zn SOD), and catalase (CAT) activities in the liver tissue. Pre-treatment with taurine or CoQ10 provided protection against PFOA-induced Cu-Zn SOD reduction in the liver tissue. Our findings evidence the depleting effect of PFOA on antioxidative systems and confirm that PFOA exerts its (neuro)toxicity through oxidative stress, but further research is needed to identify the exact toxicity mechanisms, especially in the brain.
Cilj je ovog istraživanja bio utvrditi oksidacijski stres prouzročen perfluorooktanoičnom kiselinom (PFOA) u moždanom i jetrenom tkivu Balb/c miševa te zaštitno djelovanje taurina i koenzima Q10 (CoQ10) u oba organa. U tu su svrhu životinje izložene PFOA-i u oralnoj dozi od 15 ili 30 mg/kg tjelesne težine te su u oba tkiva analizirane histopatološke promjene i izmjerene lipidna peroksidacija, ukupne razine glutationa (GSH) i aktivnosti antioksidacijskih enzima. Naši rezultati pokazuju smanjenje ukupne tjelesne težine i povećanje relativne težine organa ovisne o dozi, lipidnu peroksidaciju i smanjenu aktivnost glutation peroksidaze (GPx) u moždanom tkivu te promjene razina GSH i aktivnosti GPx, superoksid dismutaze (Cu-Zn SOD) i katalaze (CAT) u jetrenom tkivu. Prethodna primjena taurina ili CoQ10 zaštitila je životinje izložene PFOA-i od pada razina Cu-Zn SOD u jetrenom tkivu. Naši rezultati potvrđuju da PFOA iscrpljuje antioksidacijske sustave i djeluje (neuro)toksično putem oksidacijskoga stresa, no potrebna su daljnja istraživanja kako bi se precizno utvrdili njegovi mehanizmi toksičnosti, napose u mozgu.