Thymus daenensis extract prevents scopolamine­induced memory impairment through declining oxidative stress in rats.

Memory and cognitive impairment induced by oxidative stress are among the main hallmarks of Alzheimer's disease's (AD) pathology. The present study aimed to investigate the potential neuroprotective effects of Thymus daenensis (T. daenensis) extract against scopolamine­induced memory impairment and oxidative stress in rats. T. daenensis, widely distributed in Iran and Europe, is known to be a rich source of natural antioxidants and has been traditionally used for various medical purposes. The present study investigated the post­treatment effects of T. daenensis on learning and memory functions, antioxidant cellular defense, and oxidative stress using the scopolamine rat model of AD. The experiments were performed by intraperitoneal injection of scopolamine for 10 consecutive days in Wistar male rats (180-220 g). Additionally, the animals received T. daenensis extract (50­200 mg/kg) by gavage for 14 consecutive days after induction of memory impairment. The animals were divided into 8 groups, namely: control, 200 mg/kg of T. daenensis extract (D200), donepezil (DON), scopolamine (ALZ), ALZ animals treated with different doses of the extract (ALZ+D50 or 100 or 200 mg/kg) and ALZ animals treated with (ALZ+DON). The animals were then subjected to the Morris water maze (MWM) paradigm as a standard criterion for memory function assessment, and after extracting the brain tissues, the related biochemical oxidative stress parameters were determined in the brain. Our results indicated that T. daenensis extract significantly improved animals' performance in the MWM while significantly reducing oxidative stress and antioxidant imbalance. Furthermore, the extract did not show hepatotoxic effects on treated animals. In addition, the extract treatment significantly decreased both cellular malondialdehyde (MDA) and protein carbonyl (PCO) content while conversely increasing the total reduced glutathione (GSH) content and also the levels of total and endogenous antioxidants in the ferric reducing antioxidant power (FRAP) assay. It seems that the administration of T. daenensis significantly improved both cellular biochemical aspects and memory performance in animal models. Conclusively, it could be beneficial for scopolamine­induced neurotoxicity.

Protective effects of Vinca herbaceous extract against scopolamine-induced behavioral disturbances and brain oxidative stress in rats.

Ethnopharmacological relevance: Alzheimer's disease (AD) as the most common type of dementia, is affecting the life of many senior individuals around the world. Vinca herbacea Waldst. & Kit. (V. herbacea) as a middle east originated plant demonstrated antioxidant and antitumor effects. This plant traditionally used to treat diabetes and hypertension, but its mechanism remains unclear. Aim of the study: In the present study, post-treatment effects of V. herbacea on learning and memory functions, antioxidant cellular defense and oxidative stress were investigated using the scopolamine rat model of AD. Materials and methods: Wistar male rats (170-190 g) were administered Scopolamine, an anti-muscarinic drug, (2 mg/kg) for 10 days followed by V. herbacea extract (200, 300 and 400 mg/kg) and/or donepezil (DON; 1 mg/kg, which were administered before behavioral studies for 10 consecutive days. All the rats were then subjected to Morris water maze (MWM) task. Biochemical parameters of oxidative stress were quantified using the whole brain. Results: Our data showed significant decrease performance in target quadrant in water maze task following administration of scopolamine (SCOP). Also, V. herbacea and DON, did not induce any neurotoxicity and hepatotoxic effects at the highest utilized doses in healthy rats. Treatment with V. herbacea extract (200&400 mg/kg) and DON improved memory performance significantly in comparison with AD rats. In addition, V. herbacea extract in AD rats exhibited a decrease in malondialdehyde (MDA) and protein carbonyl (PCO) levels and an increase in total antioxidant capacity (FRAP) and glutathione (GSH) amounts in brain and liver. Conclusion: It seems that cholinergic deficits and oxidative stress are consistently associated with Alzheimer's disease (AD). The richness of V. herbacea in case of indole alkaloids and flavonoids confirms the potentials of this herb in management of oxidative stress, resorting synaptic acetylcholine level and improving cellular antioxidant resources.

In vitro antioxidant and free radical scavenging activity of four Alkanna species growing in Iran.

BACKGROUND: Medicinal plants are recognized as sources of natural antioxidants that can protect biological system from oxidative stress. OBJECTIVE: In this study, the antioxidant activities of four species of the Alkanna genus (Alkanna bracteosa, Alkanna frigida, Alkanna orientalis and Alkanna tricophila) were evaluated. MATERIALS AND METHODS: The dried roots of plant samples (100 g) were extracted separately by percolation method with MeOH/H2O (80/20) and four fractions were provided respectively with hexane, chloroform, ethyl acetate, butanol and water. Antioxidant activities were investigated by using 1,1-diphenyl-2-picrylhydrazyl, ferric thiocyanate and thiobarbituric acid methods and compared with quercetin (as positive control). RESULTS: The results indicated that the butanol fractions of four species had the highest antioxidant activity and radical scavenging activity compared with the other fractions studied (P < 0.05). The 50% effective concentration (half - effective doses) values of butanol fractions are less than quercetin and other fractions, so, these fractions showed potent antioxidant activity. This indicated that the active compounds in the root parts of Alkanna species dissolved in the butanol. All the fractions of four species of Alkanna had antioxidant activity, while, there were no significant differences (P > 0.05) between the total antioxidant activities of same fractions. The total antioxidant activity values of Alkanna fractions in a descending order are as follows: Butanol fraction > ethyl acetate fraction > total extract > hexane fraction > chloroform fraction > aqueous fraction. CONCLUSION: The antioxidant activities of butanol fractions of samples were higher than quercetin. This may be because most of the active compounds of Alkanna species dissolved in the butanol.