Protective Effect of Tilia americana var. mexicana Against Kainic Acid-induced Damage in Brain, Liver, and Kidney: Behavioral and Biochemical Changes

Abstract

Tiliaamericana var. mexicana (Tilia) possesses anticonvulsant, antioxidant, neuroprotective, and hepatoprotective activities. The spectrum of anticonvulsant activity in status epilepticus models has not been sufficiently explored. We evaluated the effects of ethyl acetate (EAc), and methanol (ME) extracts on kainic acid (KA)-induced seizures by measuring rats'behavior (severity and latency) and lipoperoxidation in different brain areas (cerebellum, brain hemispheres, cortex, and medulla), kidneys, and liver. Male Wistar rats were administered KA (10 mg/kg, i.p.) after three days of pretreatment with Tilia extract (100 mg/kg). The EAc and ME Tilia extracts significantly decreased the severity of phase 1 and phase 2 seizures, respectively. The ME Tilia extract increased the latency to seizure (27 ± 2 min) compared to the control (13 ± 2 min). The ME and EAc Tilia extracts significantly prevented the increased lipid peroxidation caused by KA-induced seizures in the cerebellum, brain hemispheres, cortex, medulla, liver, and kidneys. The vehicle olive oil (OO) also showed anticonvulsant effects, decreasing the severity of seizures to phase 3 and lipoperoxidation levels in the cerebellum, brain hemispheres, cortex, medulla, liver, and kidneys. The anticonvulsant activity of Tilia is mediated by antioxidant effects in central and systemic areas that involve synergistic interactions among the chemical constituents of these extracts (glucosides of quercetin and kaempferol), while vehicle OO showed the same effects, probably due to its constituent oleuropein.

Keywords: Antioxidants; Kainic Acid; Lipid Peroxides; Seizures; Tilia americana var. mexicana.

Figure 1.. (A) Latency to seizure onset in the groups receiving treatments with organic Tilia americana var. mexicana extracts or vehicle in the presence of KA. The data represent the mean ± SEM of n = 6 animals. ANOVA followed by Bonferroni multiple comparisons test. Abbreviations: Kainic acid (KA); plus olive oil (OO + KA); plus phosphate buffer (PB + KA); plus ethyl acetate extract of Tilia (EAc + KA); plus methanolic extract of Tilia (ME + KA). *P < 0.0001, ME + KA vs. all groups; (B) The effect of organic Tilia americana var. mexicana extracts or vehicle on limbic seizures induced by KA (Racine Scale). The data represent the mean ± SEM of n = 6 animals. ANOVA followed by Bonferroni multiple comparisons test. Abbreviations: Kainic acid (KA); plus olive oil (OO + KA); plus phosphate buffer (PB + KA); plus ethyl acetate extract of Tilia (EAc + KA); plus methanolic extract of Tilia (ME + KA). *P < 0.0001, ME + KA vs. OO + KA, vs. EAc + KA and vs. ME + KA.

Figure 2.. Chromatographic profile of Tilia americana var. mexicana ethyl acetate and methanolic extracts showing the presence of glycosides of quercetin (rutin, isoquercitrin, and quercitrin) and the aglycone quercetin, as well as a glycoside of kaempferol (kaempferitrin).

Figure 3.. Mechanisms proposed for the antioxidant and anti-seizure effects of the organic extracts of Tilia americana var. mexicana in the brain. Reactive oxygen species (ROS) production is accompanied by the activation of enzymes involved in ROS scavengings, such as superoxide dismutase (SOD), catalase (CAT), ascorbate-glutathione cycle enzymes (GR, GPx), and glutathione reductase (GR). KA: Kainic acid.