Methanol extract of Nigella sativa seed induces changes in the levels of neurotransmitter amino acids in male rat brain regions.

CONTEXT: Nigella sativa L. (Ranunculaceae) (NS) has been used for medicinal and culinary purposes. Different parts of the plant are used to treat many disorders. OBJECTIVE: This study investigates the effects of NS methanol extract on brain neurotransmitter amino acid levels. MATERIALS AND METHODS: We measured the changes in aspartate, glutamate, glycine and γ-aminobutyric acid in five brain regions of male Wistar rats after methanol extract treatment. Animals were injected intraperitoneally with saline solution (controls) or NS methanol extract (equivalent of 2.5 g/kg body weight) and sacrificed 1 h later or after administering 1 daily dose for 8 days. The neurotransmitters were measured in the hypothalamus, cortex, striatum, hippocampus and thalamus by HPLC. RESULTS AND DISCUSSION: Results showed significant changes in amino acids compared to basal values. Glutamate increased significantly (16-36%) in the regions analyzed except the striatum. Aspartate in the hypothalamus (50 and 76%) and glycine in hippocampus (32 and 25%), thalamus (66 and 29%) and striatum (75 and 48%) also increased with the two treatment intervals. γ-Aminobutyric acid significantly increased in the hippocampus (38 and 32%) and thalamus (22 and 40%) but decreased in the cortex and hypothalamus although in striatum only after eight days of treatment (24%). CONCLUSION: Our results suggest that injected methanol extract modifies amino acid levels in the rat brain regions. These results could be of interest since some neurodegenerative diseases are related to amino acid level imbalances in the central nervous system, suggesting the prospect for therapeutic use of NS against these disorders.

Kaurane diterpenes as mitochondrial alterations preventive agents under experimental oxidative stress conditions.

CONTEXT: Foliol, linearol, and sidol are the most common diterpenes found in Sideritis L. spp. (Lamiaceae) with a wide range of demonstrated properties including anti-inflammatory, antioxidant, and anti-apoptotic effects. OBJECTIVE: For the first time, the present work was studied for the potential protective role of these kaurane-type diterpenes on mitochondrial oxidative stress induced by H2O2 in the human astrocytoma U373-MG cell line and in the rat adrenal pheochromocytoma PC12 cell line. MATERIALS AND METHODS: Mitochondrial protection was assayed at 5 and 10 µM concentrations for 24 h (for kaurane diterpenes) and H2O2 as oxidative stress inducer (0.1 mM for PC12 cells and 1 mM for U373-MG, for 30 min). ATP concentration was determined by high-performance liquid chromatography (HPLC), and changes in mitochondrial membrane potential, caspase-3 activity as well as in cytosolic and mitochondrial calcium levels were assessed by fluorometric techniques, by using specific fluorescent probes. RESULTS: Pretreatments for 24 h with linearol and sidol, prior to H2O2 exposure, acted as mitochondrial alterations preventive agents by increasing membrane potential (over 40-60% in PC12 cells and over 10-20% in U373-MG), restoring both cytosolic and mitochondrial calcium homeostasis (linearol at 10 µM caused a 3.5-fold decrease in cytosolic calcium concentration in PC12 cells), decreasing caspase-3 activity (over 1.25-1.5-fold for linearol and sidol) and avoiding ATP depletion (linearol increased over 20% ATP level in both cell types). CONCLUSION: Our results suggest that linearol and sidol could provide protective activity by targeting mitochondria in response to the deleterious changes induced by H2O2.

Mitochondrial-targeted protective properties of isolated diterpenoids from sideritis spp. in response to the deleterious changes induced by H2O2.

Mitochondrial impairment and oxidative stress are considered widely to be central events in many forms of neurodegenerative disease. The current study has evaluated for the first time the potential protective role of three diterpenoids [andalusol (1), conchitriol (2), and lagascatriol (3)] in response to the deleterious H2O2-induced changes on mitochondrial function. U373-MG human astrocytoma cells and PC12 rat adrenal pheochromocytoma cells were used as models for evaluating the cytoprotective potential of these compounds. In the absence of diterpenoids 1-3, H2O2 compromised mitochondrial function, decreasing mitochondrial membrane potential and ATP levels, increasing caspase-3 activity, and disrupting cytosolic and mitochondrial calcium homeostasis. However, treatment with the diterpenoids, prior to H2O2, prevented these mitochondrial perturbations. In particular, 1 and 3 were the most effective compounds in protecting mitochondrial function against H2O2-induced oxidative stress in U373-MG, whereas all three diterpenoids studied were significantly active against PC12 cells. Since consistent evidence has demonstrated the contribution of H2O2 on both progression and pathological development of several human diseases associated with mitochondrial function and oxidative stress responses, compounds 1-3 are worthy of further investigation.

Nigella sativa L. seed extract modulates the neurotransmitter amino acids release in cultured neurons in vitro.

Nigella sativa L. (NS) has been used for medicinal purposes since ancient times. This study aimed to investigate the cytotoxicity of NS dry methanolic extract on cultured cortical neurons and its influence on neurotransmitter release, as well as the presence of excitatory (glutamate and aspartate) and inhibitory amino acids (gamma-aminobutyric acid-GABA-and glycine) in NS extract. Cultured rat cortical neurons were exposed to different times and concentrations of NS dry methanolic extract and cell viability was then determined by a quantitative colorimetric method. NS did not induce any toxicity. The secretion of different amino acids was studied in primary cultured cortical neurons by high-performance liquid chromatography (HPLC) using a derivation before injection with dansyl chloride. NS modulated amino acid release in cultured neurons; GABA was significantly increased whereas secretion of glutamate, aspartate, and glycine were decreased. The in vitro findings support the hypothesis that the sedative and depressive effects of NS observed in vivo could be based on changes of inhibitory/excitatory amino acids levels.

Neuroprotective and neurochemical properties of mint extracts.

Mints are aromatic plants with a tradition as medicinal remedies and culinary herbs. With the aim of investigating potential central nervous system (CNS) activities of traditional medicinal plants, four species and one hybrid of the genus Mentha (M. aquatica, M. longifolia, M. pulegium, M. suaveolens and M. x piperita) were selected. Methanolic extracts of the plants were tested for protective effects against hydrogen-peroxide-induced toxicity in PC12 cells, antioxidant activity (by ABTS and X/XO methods) and neurochemical properties (MAO-A inhibition, AChE inhibition and affinity to the GABA(A) receptor). Mentha x piperita and Mentha aquatica produced significant (p < 0.05) protection of the PC12 cells against oxidative stress. All the plants exhibited antioxidant and MAO-A inhibitory activities, M. x piperita being the most active. M. aquatica showed the highest affinity to the GABA(A)-receptor assay. Results demonstrate that mints might have effect on the CNS.

Neuroprotective and neurological properties of Melissa officinalis.

Melissa officinalis has traditionally been used due to its effects on nervous system. Both methanolic and aqueous extracts were tested for protective effects on the PC12 cell line, free radical scavenging properties and neurological activities (inhibition of MAO-A and acetylcholinesterase enzymes and affinity to the GABA(A)-benzodiazepine receptor). The results suggest that the plant has a significant (P < 0.05) protective effect on hydrogen peroxide induced toxicity in PC12 cells. The radical scavenging properties were also investigated in cells and in cell free systems, where this plant was shown to be a good free radical scavenger. The MAO-A bioassay was also performed to detect possible antidepressant activities demonstrating that both extracts inhibited this enzyme, which has a key role in neurotransmitters metabolism. However, no activity was detected in the acetylcholinesterase and GABA assays. In general, the methanolic extract was more effective than the aqueous.