The application of adsorbent bentonite in oxidative stress induced by paraquat

The protective effect of bentonite (natural and synthetic) in oxidative stress induced by paraquat was studied on 32 adult male Wistar rats. The animals were divided into four groups (n=8). The first group received only paraquat p.o. (via a gastric tube). An hour after administration of paraquat, the second and the third group were treated with natural and synthetic bentonite, respectively, while the fourth group was untreated (control). All three experimental groups were treated once a day, throughout 8 consecutive days. Blood samples were taken 0, 1, 4, 6 and 8 days after the beginning of the treatment. Oxidative stress induced by paraquat was estimated by means of catalase activity (CAT - mmol/H2O2/min/g Hb) and malondialdehyde quantity (MDA - nmol/g Hb). Oxidative stress proved to be significant an hour and 192 hours after the beginning of chronic intoxication by paraquat. Both natural and synthetic bentonite expressed a protective action from oxidative stress in the period from 24 h to 144 h post application, acting through the external capacity of cationic exchange, which is known to be approximately 10%. The absorption of paraquat depends on the size of the molecule and its polarisation and is performed by the mechanisms of ion exchange (ionic and electrostatic interaction). Nevertheless, both absorbents developed a significant protective effect (approximately 50 %) 1 h and 192 h after the first application of paraquat, indicating that these protectors act as molecular sieves and thus suppress the process of lipid peroxidation and the development of even more intensive oxidative stress.