Non-clinical toxicity of (+)-limonene epoxide and its physio-pharmacological properties on neurological disorders.

The compound (+)-limonene epoxide has antioxidant, anxiolytic, and antihelminthic properties. However, investigations to determine its long-term exposure were not performed. We investigated the systemic toxicological profile after chronic exposure as well as the antidepressant and antiepileptic potentialities of (+)-limonene epoxide on mice. Initially, we evaluated acute toxicity on Artemia salina nauplii and cytotoxicity on mice erythrocytes and peripheral blood mononuclear cells (PBMC). Aftterwards, mice were chronically treated for 120 days by gavage with (+)-limonene epoxide (25, 50, and 75 mg/kg/day) and this exposure was assessed by pathophysiological measurements. For antidepressant and anticonvulsivant analysis, we performed the forced swimming and tail suspension protocols and pentylenetetrazol- and picrotoxin-induced seizures, respectively. (+)-Limonene epoxide showed a LC50 value of 318.7 µg/mL on A. salina shrimps, caused lysis of red blood cells at higher concentrations only but did not show cytotoxicity on PMBC, which suggests pharmacological safety if plasma concentrations do not exceed 100 µg/mL. Macroscopic, hematological, clinical chemistry, and nutritional changes were not detected, though focal areas of hepatic necrosis, inflammatory infiltrate, and karyolysis have been detected at 75 mg/kg/day. The compound inhibited the developing of pentylenetetrazol- and picrotoxin-induced seizures, decreased deaths, and reduced immobility times, mainly at 75 mg/kg. So, it reversed reserpine effects, suggesting antidepressant effects should be linked to serotonergic and/or adrenergic transmission. It is feasible that (+)-limonene epoxide plays a benzodiazepine-like anticonvulsive action and may be also recommended as an antidote for poisonings caused by central depressants.

Nerolidol and its Pharmacological Application in Treating Neurodegenerative Diseases: A Review.

BACKGROUND: Research on natural bioactive compounds has increased exponentially over the last decades. The discovery of new phytochemicals that possess pharmaceutical properties is useful in the development of therapeutic alternatives. The nerolidol (3,7,11-trimetil-1,6,10-dodecatrien-3-ol or 3,7,11-trimetildodeca-1,6,10-trien-3-ol) has been extensively studied for its therapeutic potential because of its pharmacological activities in the treatment of neurodegenerative diseases. METHOD: All articles and patents regarding nerolidol and its pharmacological properties were revised, focusing mainly on the important properties in the treatment of neurodegenerative diseases. A thorough search in article databases (Science Direct, MEDLINE/PubMed, Scopus and Scielo) and patent database (WIPO, EPO, ESPTO, LATIPAT and INPI) was performed over the course of this study. RESULTS: Several studies stood out for their relevance regarding the treatment of neurodegenerative diseases. Nerolidol demonstrated anticholinesterasic, antioxidant, antinociceptive, anti-inflammatory and anxiolytic activities, thus classifying it as a promising phytochemical for the development of therapeutic drugs. CONCLUSION: Analysis suggested that nerolidol is a promising target for new drugs and treatment of neurodegenerative diseases.

Evaluation of p-cymene, a natural antioxidant.

CONTEXT: Several studies have demonstrated that essential oils and their major components have antioxidant activity. p-Cymene is a monoterpene and a major constituent of essential oils of various species of plants. OBJECTIVE: This paper evaluated the antioxidant potential of p-cymene in the hippocampus of mice by determining the levels of thiobarbituric acid reactive substances (TBARS), nitrite content, and activity of catalase (CAT) and superoxide dismutase (SOD). MATERIALS AND METHODS: Swiss mice were intraperitoneally treated with 0.05% Tween 80 dissolved in 0.9% saline solution, ascorbic acid 250 mg/kg, and p-cymene at doses of 50, 100, and 150 mg/kg, respectively. After treatment, all groups were observed for 24 h, afterwards, the groups were euthanized for removal of the brain and dissection of the hippocampus. RESULTS: The results of treatment with p-cymene were a significant decrease in lipid peroxidation and nitrite content at a dose of CYM 50: 65.54%, CYM 100: 73.29%, CYM 150: 89.83%, and CYM 50: 71.21%; CYM 100: 68.61% and CYM 150:67%, respectively, when compared with the control group. The results showed that at all tested doses, p-cymene produces an increase in SOD and catalase activity significantly at a dose of CYM 50: 22.7%, CYM 100: 33.9%, CYM 150: 63.1%, and CYM 50: 119.25%, CYM 100: 151.83% and CYM 150: 182.70%, respectively, when compared with the vehicle-treated group. DISCUSSION AND CONCLUSION: The result of this study shows that p-cymene has an antioxidant potential in vivo and may act as a neuroprotective agent in the brain. This compound may present a new strategy in the development of treatment for many diseases in which oxidative stress plays an important pathophysiological role.

Potential antioxidant and anxiolytic effects of (+)-limonene epoxide in mice after marble-burying test.

The present study evaluated anxiolytic activity of (+)-limonene epoxide (EL), through the marble burying test (MBT) assay, and the antioxidant potential in vitro and in vivo in mice hippocampus of adult mice subjected to experimental anxiety protocol. For behavioral studies, and in vivo antioxidant analyses, mice were treated orally with 0.05% Tween 80 dissolved in 0.9% saline solution (vehicle), ascorbic acid 250 mg/kg, diazepam (2 mg/kg) and EL (25, 50 and 75 mg/kg). Results suggest an anxiolytic effect of (+)-limonene epoxide. A reduction in number of buried marbles in groups treated with EL doses of 25, 50 and 75 mg/kg was observed when compared with diazepam and vehicle groups. This reduction was observed after treatments with single and repeated doses, reinforcing the hypothesis of anxiolytic effect. The anxiolytic effect was reversed by pretreatment with flumazenil (25 mg/kg, o.r) in the same way as it was observed with diazepam (2 mg/kg, o.r, positive control), suggesting that these drugs possess a similar mechanism of action. In antioxidant tests in vitro, the concentrations from 0.9 to 7.2 µg/ml were tested. The results of in vitro antioxidant tests demonstrated a 50% inhibitory effective concentration of 0.7342, 1.296 and 1.169 µg/ml against the formation of nitrite ion, hydroxyl radical and reactive substances to thiobarbituric acid, respectively. The treatment with EL reduced the lipid peroxidation level and nitrite content, suggesting an antioxidant role in vivo since it was able to reduce the formation of reactive species derived from oxygen and nitrogen. Furthermore, the EL increased activity of enzymes catalase and superoxide dismutase in mice hippocampus, suggesting that their role may be due to antioxidant upregulation of these enzymes.