Evidence for involvement of the monoaminergic system in antidepressant-like activity of an ethanol extract of Boerhaavia diffusa and its isolated constituent,punarnavine, in mice

Context: Boerhaavia diffusa Linn. (Nyctaginaceae) roots possess potent antioxidant, antistress, and anticonvulsant activities. It is used as a medicinal plant in Ayurvedic and natural herbal medicines.

Objective: To evaluate the effect of Boerhaavia diffusa root ethanol extract and its active constituent, punarnavine, on depression in Swiss albino mice.

Materials and methods: Ethanol extract (50, 100, and 200?mg/kg, p.o.) and punarnavine (20 and 40?mg/kg, p.o.) were separately administered to 22 and 17 groups of mice, respectively, for 14 successive days followed by testing in the tail suspension and forced swim tests (FST). About 2% w/v gum acacia and double distilled water were used as controls for the extract and punarnavine, respectively.

Results: Antidepressant-like effect of the lowest dose (50?mg/kg) of the extract and lower dose (20?mg/kg) of punarnavine were found to be comparable to fluoxetine. The ED₅₀ value of the ethanol extract was 26.30?mg/kg (FST) and 33.11?mg/kg (tail suspension test); and of punarnavine was 15.14?mg/kg (FST) and 17.38?mg/kg (tail suspension test). The drugs did not show any significant effect on locomotor activities of mice. Prazosin (α₁-adrenoceptor antagonist), sulpiride (selective D₂-receptor antagonist), para-chlorophenylalanine) (p-CPA) (tryptophan hydroxylase inhibitor), and baclofen (GABA_B agonist) significantly attenuated the extract and punarnavine induced-antidepressant-like effect in the tail suspension test. The extract and punarnavine also significantly reduced mouse brain monoamine oxidase (MAO)-A levels, but there was no significant effect on plasma corticosterone levels.

Conclusion: Ethanol extract of Boerhaavia diffusa and punarnavine produced an antidepressant-like effect in mice probably through interaction with monoaminergic and GABAergic systems.     

Effect of pregabalin on fear-based conditioned avoidance learning and spatial learning in a mouse model of scopolamine-induced amnesia

Objectives: Cognitive deficits are one of the frequent symptoms accompanying epilepsy or its treatment.

Methods: In this study, the effect on cognition of intraperitoneally administered antiepileptic drug, pregabalin (10?mg/kg), was investigated in scopolamine-induced memory-impaired mice in the passive avoidance task and Morris water maze task. The effect of scopolamine and pregabalin on animals’ locomotor activity was also studied.

Results: In the retention phase of the passive avoidance task, pregabalin reversed memory deficits induced by scopolamine (p?p?p?p?Discussion: In passive avoidance task, pregabalin reversed learning deficits induced by scopolamine. In the Morris water maze, pregabalin did not influence spatial learning deficits induced by scopolamine. These results are relevant for epileptic patients treated with pregabalin and those who use it for other therapeutic indications (anxiety, pain).     

Assessment of luteolin isolated from Eclipta alba leaves in animal models of epilepsy

Context: Eclipta alba (Linn) Hassk. (Asteraceae) has been reported to be a nerve tonic and has been used to treat epilepsy in folk medicine.

Objective: The present study isolates and characterizes luteolin from E. alba and evaluates its antiepileptic potential in chemically induced acute and chronic models in mice.

Materials and methods: The methanol extract (16.85% w/w) of E. alba leaves was subjected to fractionation for isolation of luteolin. In acute pentylenetetrazole (PTZ) model, luteolin (5, 10, 20?mg/kg, i.p.) was administered 30?min prior to PTZ injection (100?mg/kg) in Swiss albino mice. Kindling was induced by chronic administration of PTZ (35?mg/kg) on every alternate day (48 days). Luteolin was investigated on the course of kindling development and oxidative stress markers [reduced glutathione (GSH) and malondialdehyde (MDA)] in kindled mice.

Results: Single-dose pretreatment with luteolin (10 and 20?mg/kg, i.p.) was found to be effective in an acute PTZ model (100% protection from mortality) and it did not exhibit any effect on motor coordination at the same doses. PTZ-induced kindling was significantly (p?p?p?Discussion and conclusion: The results of the present study demonstrated that luteolin had an anticonvulsant effect in an acute PTZ model. Luteolin exhibited and inhibitory effect on the course of kindling and associated oxidative stress and hence could be a potential molecule in the treatment of epilepsy.     

Hydroalcoholic extract of Myrtus communis can alter anxiety and sleep parameters: a behavioural and EEG sleep pattern study in mice and rats

Context: Myrtus communis L. (Myrtaceae), myrtle, is an evergreen shrub with strong antibacterial, anti-inflammatory, antihyperglycemic and antioxidant activities. Also, it is used as a sedative-hypnotic plant in Iranian traditional medicine.

Objective: This study evaluates the effect of 80% ethanolic extract of M. communis leaves on sleep and anxiety in mice and rats.

Materials and methods: Male NMRI mice were subjected to open field, righting reflex, grip strength and pentylentetrazole-induced seizure tests. Male Wistar rats were used to evaluate the alterations in rapid eye movement (REM) and non-REM (NREM) sleep. They were treated with 25–400?mg/kg doses of the extract intraperitoneally.

Results: The applied doses (50–200?mg/kg) of M. communis extract increased vertical (ED_50?=_?40.2?±?6.6?mg/kg) and vertical and horizontal activity (ED_50?=_?251?±?55?mg/kg), while treatment with 200 and 400?mg/kg attenuated muscle tone significantly compared to vehicle treated animals (p?<?0.001 for all) in a dose-independent manner. Also, a significant hypnotic and not anticonvulsant effect was observed when animals were treated with 200?mg/kg of the extract (p?<?0.01). In this regard, electroencephalography results showed that REM sleep time was decreased (2.4?±?0.5%), while total and NREM sleep times were increased significantly compared to the control group of mice (82.5?±?7.6%).

Discussion and conclusion: The data show the anxiolytic and muscle relaxant effect of the extract without anticonvulsant activities. The anxiolytic, myorelaxant and hypnotic effects without effect on seizure threshold are in line with the effect of a alpha 2 GABA receptor agonist.     

Antinociceptive and anti-hyperalgesic effects of bis(4-methylbenzoyl) diselenide in mice: Evidence for the mechanism of action

Abstract

Context: The organoselenium compounds have been described to demonstrate several biological activities, including pain management.

Objective: This study investigated the antinociceptive, hyperalgesic, and toxic effects of oral administration of bis(4-methylbenzoyl) diselenide (BMD) in mice.

Materials and methods: The antinociceptive and anti-hyperalgesic effects of BMD (1, 5, 10, 25, and 50?mg/kg, p.o.) were evaluated using models of nociception: formalin, capsaicin, bradykinin (BK), cinnamaldehyde, phorbol myristate acetate (PMA), 8-bromo-cAM, and glutamate-induced nociception; and mechanical hyperalgesia induced by carrageenan (Cg) or complete Freund's adjuvant (CFA). The acute toxicity was evaluated by biochemical markers for hepatic and renal damages.

Results: BMD significantly inhibited the licking time of the injected paw in the early and late phases of a formalin test with ED₅₀ values of 14.2 and 10.8?mg/kg, respectively. This compound reduced nociception produced by capsaicin (ED₅₀ of 32.5?mg/kg), BK (ED₅₀ of 24.6?mg/kg), glutamate (ED₅₀ of 28.7?mg/kg), cinnamaldehyde (ED₅₀ of 18.9?mg/kg), PMA (ED₅₀ of 9.6?mg/kg), and 8-bromo-cAMP (ED₅₀ of 24.8?mg/kg). In the glutamate test, the pretreatment with nitric oxide (NO) precursor, l-arginine, reversed antinociception caused by BMD or N^ω-nitro-l-arginine (_L-NOARG), but the effect of BMD was not abolished by naloxone. Mechanical hyperalgesia induced by Cg and CFA was attenuated by BMD, 70?±?4% and 65?±?4%, respectively. Furthermore, a single oral dose of BMD did not change plasma aspartate (AST) and alanine aminotransferase (ALT) activities or urea and creatinine levels.

Conclusion: BMD demonstrated as a promising compound because of the antinociceptive and anti-hyperalgesic properties in mice.     

Role of GABAB receptors and p38MAPK/NF-κB pathway in paclitaxel-induced apoptosis of hippocampal neurons

Context: The effects of the anticancer drug paclitaxel on learning and memory are rarely studied.

Objective: This study investigated changes in GABA_B receptor expression during paclitaxel-induced apoptosis of hippocampal neurons and the role of the p38MAPK/NF-κB pathway in this process.

Materials and methods: Hippocampal neurons isolated from neonatal Sprague–Dawley rats were divided into six groups: Control (C), SB (10?µL of 10-µmol/L SB203580), SN (53?µg/mL SN50), N (1?µmol/L paclitaxel), SB?+?N (10?µmol/L SB203580?+?1?µmol/L paclitaxel) and SN?+?N (53?µg/mL SN50?+?1?µmol/L paclitaxel). Cells in different groups were treated with corresponding agents for 24?h at 37?°C. The apoptosis rate and protein levels of GABA_B1 receptors and NF-κB p65 were evaluated. Rat models of neuropathic pain was induced by paclitaxel and were divided into four groups such as N, B?+?N, SN?+?N and SN?+?B?+?N groups. Rats in the N group received intrathecal injections of normal saline solution. Rats in the B?+?N group received intrathecal injections of 10?μL baclofen (0.05?μg/μL). Rats in the SN?+?N and SN?+?B?+?N groups received intrathecal injections of SN50 and SN50 plus baclofen, respectively. Spatial learning and memory were evaluated in rat models based on the escape latency and the number of crossings over the platform and protein levels of GABA_B1 receptors, NF-κB, IL-1β and TNFα were measured by immunohistochemistry assay and western blot.

Results: The neuronal apoptosis rate was significantly increased in N (49.16?±?3.12)%, SB?+?N (31.18?±?3.02)% and SN?+?N (28.47?±?3.75)% groups, accompanied by increased levels of GABA_B1 receptors and NF-κB p65 (p?p?B1:9.0?±?1.6, NF-κB p65:29.6?±?2.4, IL-1β: 30.4?±?3.4, TNFα: 31.0?±?3.4), B?+?N, SN?+?N and SN?+?B?+?N groups evidently increased levels of GABA_B1 receptor (B?+?N:SN?+?N:SN?+?B?+?N?=?19.4?±?2.1:20.8?±?1.9:28.0?±?1.9) but significantly decreased levels of NF-κB p65 (B?+?N:SN?+?N:SN?+?B?+?N?=?21.2?±?1.5:18.6?±?2.1:12.6?±?1.5), IL-1β (B?+?N:SN?+?N:SN?+?B?+?N?=?22.0?±?1.0:19.6?±?1.8:14.6?±?1.5) and TNF α (B?+?N:SN?+?N:SN?+?B?+?N?=?23.0?±?1.6:22.2?±?0.8:16.6?±?1.7). Similar findings were found in western blot analysis.

Discussions and conclusions: Paclitaxel may reduce cognitive function in rats through the p38MAPK/NF-κB pathway and GABA_B1 receptors.     

Involvement of GABAergic system in regulation of the anxiolytic- and antidepressant-like effects of Scrophularia striata extract in rats

Abstract

Context: Neuropsychiatric disorders, like anxiety and depression, are global problems for clinical researchers in neurology. Recently, some authors have shown neuroprotective and anti-inflammatory effects of Scrophularia striata Boiss (Scrophulariaceae) extract in rodents.

Objective: The purpose of the current study was to investigate the effects of S. striata extract on anxiety and depressant-like behaviors and find a possible mechanism for these impacts.

Materials and methods: In this study, the elevated plus-maze (EPM) and forced swimming test (FST), which are useful models for selective identification of anxiolytic and antidepressant drug effects in rodents, were used. We investigated the effects of S. striata ethanol extract at different doses (20, 50, 100, 160 and 220?mg/kg) on anxiety and depression behaviors in the EPM and FST, and then we assessed the role of γ-aminobutyric acid (GABA)_A receptor in modulation of the effects of S. striata extract in the brain.

Results: Our results showed that effective doses of S. striata (100 and 160?mg/kg) increased the percentages of open arm time and entries in the EPM and decreased immobility time in the FST in comparison with control group, indicating anxiolytic and antidepressant effects, respectively. Moreover, intracerebroventricular administration of GABA_A receptor agonist (muscimol; 1?µg/rat) enhanced the impact of S. striata, and GABA_A receptor antagonist (bicuculline; 1?µg/rat) blocked these effects in rats, indicating that significant interactions existed between S. striata and the GABAergic system in the brain.

Discussion and conclusion: Findings of this study suggest that anxiolytic and antidepressant effects of S. striata may be modulated via the GABAergic system.     

Anticonvulsant activity of ethanol extracts of Vetiveria zizanioides roots in experimental mice

?Abstract

Context: Vetiveria zizanioides Linn. (Gramineae), an aromatic plant commonly known as vetiver, is traditionally used for various ailments. Ethanol and aqueous extract of this plant found extensive use in Indian folklore medicine and used in treatment of a wide range of disorders including seizure. However, the anticonvulsant activity of this plant has not been studied.

Objective: To evaluate anticonvulsant activity of ethanol extract of V. zizanioides (EEVZ) in experimental mice.

Materials and methods: Anticonvulsant activity of EEVZ was determined by maximal electroshock stimulation (MES) and pentylenetetrazole (PTZ) in mice for 8?d experimental protocol. The extract at a dose of 100, 200 and 400?mg/kg body weight was administered once by oral route.

Results: LD₅₀ value of EEVZ in mice was found at a dose of 600?mg/kg body weight. EEVZ at a dose of 400?mg/kg significantly (p?<?0.001) reduced flexion (l5.98 to 3.73?s), extension (13.73 to 0.96?s), clonus (14.07 to 4.93?s), stupor (6.29 to 1.22?s) in the MES model. Further, it increases onset of clonic (88.25 to 708.32?s/30?min) and tonic (139.52 to 1126.39?s/30?min) in the PTZ model. In the PTZ model, 33% normal control and 83% EEVZ (100?mg/kg) animals were alive, while 100% protection was achieved in standard drug phenobarbital (20?mg/kg), EEVZ (200?mg/kg) and EEVZ (400?mg/kg) animals.

Discussion and conclusion: Findings demonstrate that V. zizanioides shows significant anticonvulsant activity in mice.     

Comparative effects of green and black tea extracts on lowering serum uric acid in hyperuricemic mice

Context: Tea (Camellia sinensis (L.) Kuntze [Theaceae]) is used to induce urination and inducing nervous excitation. Green and black teas have multifarious physiological functions. The different effects of green and black tea aqueous extracts (GTEs and BTEs) on hyperuricemia are not definitely reported.

Objective: The different effects of GTEs and BTEs on lowering serum uric acid (UA) in hyperuricemic mice were determined.

Materials and methods: Kunming mice were divided into nine groups (n?=?6/each group). GTEs and BTEs at the doses of 0.5, 1 and 2?g/kg were orally administrated to mice for seven days, respectively. Hepatic xanthine oxidase (XOD) and adenosine deaminase (ADA) activities as mechanisms of actions were assessed.

Results: Research indicated that the LD₅₀ of tea extract is greater than 2?g/kg in mice. UA levels were suppressed significantly with dose-dependent treatment of 0.5, 1 and 2?g/kg BTEs (up to 25.5%, 28.7% and 29.8%, respectively); the serum UA levels were decreased by GTEs but not significant. The activities of XOD and ADA in high dose (2?g/kg) groups of both GTEs and BTEs were notably lower than those of the model group.

Discussion and conclusions: The results suggested that both GTEs and BTEs have hypouricaemic and renal protective effects on hyperuricemic mice and the latter one was better. Our study sheds light on the research and development of anti-hyperuricemic functional foods and drugs from tea.     

Evaluation of herbal antimalarial MAMA decoction-amodiaquine combination in murine malaria model

Context: Co-administration of amodiaquine with MAMA decoction (MD), an herbal antimalarial drug comprising the leaves of Mangifera indica L. (Anacardiaceae), Alstonia boonei De Wild (Apocynaceae), Morinda lucida Benth (Rubiaceae) and Azadirachta indica A. Juss (Meliaceae) was investigated. The practice of concurrent administration of herbal medicines with orthodox drugs is currently on the increase globally.

Objective: The study was designed to investigate the possible enhancement of the antimalarial potency as well as possible herb–drug interaction resulting from concurrent administration of MAMA decoction with amodiaquine (AQ).

Materials and methods: Combinations of MD with AQ were investigated in chloroquine (CQ)-sensitive Plasmodium berghei NK 65 in varying oral doses (mg/kg) at: sub-therapeutic [MD30?+?AQ1.25], therapeutic [MD120?+?AQ10] and median effective [MD40?+?AQ3.8], using chemosuppressive and curative antimalarial test models. Secondly, P. berghei ANKA (CQ-resistant)-infected mice were orally treated with MD 120, 240, [MD120?+?AQ10] and [MD240?+?AQ10] mg/kg, using both models. The survival times of mice were monitored for 28 d.

Results: ED₅₀ values of MD and AQ were 48.8 and 4.1?mg/kg, respectively. A total parasite clearance of CQ-sensitive P. berghei NK65 was obtained with the therapeutic combination dose in the curative test giving an enhanced survival time. In CQ-resistant P. berghei ANKA-infected mice, [MD120?+?AQ10] and [MD240?+?AQ10] mg/kg gave comparable activities with AQ (10?mg/kg) in both models.

Conclusion: The therapeutic combination dose gave total parasite clearance of CQ-sensitive P. berghei NK65, whereas none of the doses tested showed notable activity against CQ-resistant P. berghei ANKA.     

The antitumour effects of eudesmin on lung cancer by inducing apoptosis via mitochondria-mediated pathway in the tumour cells

Context: Limonoids possess broad range of biological activities, including antitumour, antimicrobial and antioxidant activities, etc. Eudesmin (EDN) is a type of limonoid which also possesses various activities. However, there is no report on the antitumour lung cancer (LC) activities of this compound.

Objective: The present study investigates the antitumour effects of EDN and its potential molecular mechanisms.

Materials and methods: The in vitro antitumour effects of EDN on LC A549 cells were evaluated by using MTT assay. The in vivo antitumour effects were investigated on a xenograft athymic nude mouse model. The mice were administered orally with EDN (10, 20 and 40?mg/kg) once daily for 28 days. Effects of EDN on apoptosis-related or signalling proteins (Bcl-2, Bax, caspase-3, caspase-9, P53, Akt and JNK) were assayed by western blot analysis.

Results: EDN showed significant inhibitory effects on the growth of LC A549 cells in vitro with the half maximal inhibitory concentration (IC₅₀) of 18.3?μM. By treating with EDN (10, 20 and 40?μM), expression of caspase-3, caspase-9, Bax, P53 and phosphorylated JNK in A549 cells were significantly upregulated, whereas expression of Bcl-2 and Akt phosphorylation were significantly down-regulated. Interestingly, EDN-induced apoptosis could be attenuated by JNK inhibitor. In addition, in vivo experiments also indicated EDN (10, 20 and 40?mg/kg) had significant antitumour effects (p?Conclusions: Overall, the results indicated that EDN possesses significant antitumour effects on LC and the possible mechanism might be related to induction of mitochondria-mediated apoptosis.     

Anticonvulsant activity of aqueous fraction of Carissa edulis root bark

Abstract

Context: Carissa edulis Vahl (Apocynaceae) is used in Nigerian folk medicine to manage a plethora of diseases including epilepsy, cancer, and inflammation; its efficacy is widely acclaimed among communities of northern Nigeria.

Objective: This study establishes anticonvulsant activities of aqueous fraction of ethanol root bark extract of Carissa edulis (RAF) and sub-fractions (S1 and S2) in animal models.

Materials and methods: We evaluated the acute toxicity of the RAF, S1 and S2, and the anticonvulsant activity using pentylenetetrazole (PTZ), picrotoxin, strychnine, N-methyl-d-aspartate (NMDA), isoniazid (INH), and aminophylline-induced seizures in mice. Their effects on maximal electroshock (MES) and kindling-induced seizures were studied in chicks and in rats, respectively, and in the electrophysiological study. The doses used for RAF were 150, 300, and 600?mg/kg while S1 and S2 were 250, 500, and 1000?mg/kg. Both RAF and sub-fractions were administered once during the experiment.

Results: The intraperitoneal LD₅₀ of the RAF was estimated to be 2222.61?mg/kg and that of the S1 and S2 were above 5000?mg/kg. RAF protected the mice by 50% while sub-fractions by 16.67% against PTZ-induced seizures. RAF offered 33.33 and 16.67% protection against strychnine and NMDA models, respectively. However, RAF offered 66.67–33.33% protections against aminophylline-induced seizures at doses of 150 and 600?mg/kg, but RAF, S1, and S2 had no effect on MES-induced seizures.

Discussion and conclusion: Our results validate the use of the plant traditionally in the management of epilepsy, thus supporting the appraisal of biologically active components of this plant as antiepileptic agents.     

Metformin attenuates hepatic insulin resistance in type-2 diabetic rats through PI3K/Akt/GLUT-4 signalling independent to bicuculline-sensitive GABAA receptor stimulation

Context: Metformin attenuates type-2 diabetes mellitus (T2DM)-induced hepatic dysfunction and altered PI3K/Akt/GLUT-4 signalling in experimental studies. However, its effect on bicuculline-sensitive gamma amino butyric acid (GABA)-A receptor (GABA_AR)-mediated calcium-dependent PI3K/Akt/GLUT-4 signalling in liver challenged to T2DM has not been established.

Objective: The effectiveness of metformin on bicuculline-sensitive GABA_AR-mediated hepatic insulin signalling was carried out in presence or absence of bicuculline (2.0?mg/kg, i.p.) in experimental T2DM rats.

Materials and methods: The whole experimental design was divided into three independent sets of experiments. Each set comprised seven groups of six male rats each. T2DM was induced in the animals by administering streptozotocin (45?mg/kg, i.p.) and nicotinamide (110?mg/kg, i.p.) at a time lag of 15?min except control group rats in three experiments. Metformin and/or bicuculline or wortmannin were administered once daily for one week from seventh day of streptozotocin injection in all the experimental sets.

Results: Metformin attenuated T2DM-induced hyperglycaemia in glucose (40%) and insulin (50%) tolerance tests in rats. Metformin also attenuated T2DM-induced hyperglycaemia (40%), hyperinsulinaemia (30%), insulin resistance (50%) and β-cell dysfunction (300%) in the animals. Metformin did not attenuate T2DM-induced decrease in rat hepatic intracellular calcium. Further, metformin mitigated T2DM-induced decrease in hepatic phosphorylated Akt and GLUT-4 translocation in the animals. The anti-diabetic activity of metformin was abolished by wortmannin but not with bicuculline co-administration in T2DM animals.

Discussion and conclusion: These results suggest that metformin ameliorated T2DM-induced hepatic insulin resistance through bicuculline-sensitive GABA_A receptor-independent PI3K/Akt/GLUT-4 signalling pathway in animals.     

Prunus mume leaf extract lowers blood glucose level in diabetic mice

Context Diabetes is a common metabolic disease with long-term complications. Prunus mume Sieb. et Zucc. (Rosaceae) fruits have shown to ameliorate glucose intolerance. However, the antidiabetic effects of P. mume leaves have not been investigated.

Objective This study evaluated the effects of P. mume leaf 70% ethanol extract (PMLE) on alleviating diabetes in vivo and in vitro.

Materials and methods PMLE was fractionated into n-hexane, dichloromethane (CH₂Cl₂), ethyl acetate (EtOAc), n-butanol (BuOH) and water. Polyphenol and flavonoid contents in PMLE fractions were determined using Folin–Ciocalteu reagent and the aluminium chloride colorimetric method, respectively. We evaluated α-glucosidase inhibition using a microplate reader at 400?nm. Adipocyte differentiation by lipid accumulation was measured using Nile Red staining. Male imprinting control region (ICR) mice were injected with streptozotocin (STZ, 100?mg/kg, i.p.). High-fat diets were provided for three weeks prior to PMLE treatments to induce type 2 diabetes. PMLE (0, 5, 25 or 50?mg/kg) was administrated for four weeks with high-fat diets.

Results The EtOAc fraction of PMLE inhibited α-glucosidase activity (IC₅₀?=?68.2?μg/mL) and contained 883.5?±?14.9?mg/g of polyphenols and 820.1?±?7.7?mg/g of flavonoids. The 50?mg/kg PMLE supplement reduced 40% of blood glucose level compared to obese/diabetes mice. Obese/diabetic mice treated with 50?mg/kg PMLE showed a lower level of triacylglycerol (320.7?±?20.73?mg/dL) compared to obese/diabetes mice (494.9?±?14.80?mg/dL).

Conclusion The data demonstrate that P. mume leaves exert antidiabetic effects that may be attributable to high concentrations of polyphenols and flavonoids.     

Zanthoxylum alatum abrogates lipopolysaccharide-induced depression-like behaviours in mice by modulating neuroinflammation and monoamine neurotransmitters in the hippocampus

Context: Depression is an inflammatory, commonly occurring and lethal psychiatric disorder having high lifetime prevalence. Zanthoxylum alatum Roxb. (Rutaceae), commonly called Timur, has high medicinal value and is used ethnomedicinally for the treatment of various diseases.

Objective: To evaluate the effect of hexane extract of Z. alatum seeds (ZAHE) on lipopolysaccharide (LPS)-induced depression-like behaviour in Swiss albino mice.

Materials and methods: Mice were treated with ZAHE (100 and 200?mg/kg, p.o.) and imipramine (10?mg/kg injected i.p.) for 14?days. On 14th day of the treatment, depression-like behaviour was induced by LPS (0.83?mg/kg injected i.p.) and after 24?h of LPS administration, it was assessed by measuring behavioural parameters and biochemical estimations.

Results: Behavioural tests, including the open field test, forced swimming test, tail suspension test and sucrose preference test revealed that ZAHE (100 and 200?mg/kg, p.o.) and imipramine (10?mg/kg injected i.p.) alleviated the depression symptoms of LPS-induced mice. Moreover, ZAHE treatments reversed the LPS-induced alterations in the concentrations of norepinephrine and serotonin (5-HT) and inhibited the expression of brain-derived neurotrophic factor, pro-inflammatory cytokines and oxido-nitrosative stress in the mice. Acute toxicity was calculated to be LD₅₀ >?2500?mg/kg.

Discussion and conclusions: This study showed that LPS-induced depression in mice was significantly prevented by ZAHE at both the dosages. In conclusion, ZAHE exhibited an antidepressant activity by altering monoaminergic neurotransmitters in the brain combined with its anti-inflammatory potential. Thus, it could be an effective therapeutic against inflammation-induced depression and other brain disorders.     

Anti-inflammatory and anti-proliferative activities of the wild edible cruciferous: Diplotaxis simplex

Context The present study deals with new biological properties of the wild edible Diplotaxis simplex (Viv.) Spreng (Brassicaceae).

Objectives The current study evaluates the antioxidant, the anti-inflammatory and the anti-cancer properties of ethyl acetate and ethanol extracts from D. simplex flowers.

Materials and methods The anti-proliferative activity of the extracts (10–70?μg/mL) was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) against human colon cancer cell line Caco-2. The anti-inflammatory potential was evaluated by the inhibitory effect of the extracts (1.5–7.5?mg/mL) on phospholipase A2 activity as well as on carrageenan-induced paw oedema in mice. Extracts (200?mg/kg) or indomethacin (50?mg/kg) as positive control were injected intraperitoneally for albino mice prior to the induction of the oedema by carrageenan. Antioxidant activities were investigated using various complementary methods.

Results Flower extracts contained a high level of polyphenolics (17.10–52.70?mg GAE/g) and flavonoids (74.20–100.60?mg QE/g), which correlate with its appreciable antioxidant potential in β-carotene peroxidation (IC₅₀ value: 12.50–27.10?μg/mL), DPPH^? radical-scavenging (IC₅₀ value: 0.20–0.40?mg/mL), Fe^3+?reducing (EC₅₀ value: 0.10–0.14?mg/mL) and Fe^2+?chelating (IC₅₀ value: 0.20–0.60?mg/mL) assays. These extracts were effective in inhibiting cancer cell growth (IC₅₀ value: 62.0–63.25?μg/mL). Besides, the ethyl acetate extract inhibited phospholipase A2 activity (IC₅₀ value: 2.97?mg/mL) and reduced the paw oedema in mice (from 0.38?±?0.01 to 0.24?±?0.01?cm), 4?h post-carrageenan challenge.

Conclusion These data suggest that D. simplex may be useful as a candidate in the treatment of inflammation and the colon cancer.     

Chrysosplenetin inhibits artemisinin efflux in P-gp-over-expressing Caco-2 cells and reverses P-gp/MDR1 mRNA up-regulated expression induced by artemisinin in mouse small intestine

Context: CYP3A4 and P-gp together form a highly efficient barrier for orally absorbed drugs and always share the same substrates. Our previous work revealed that chrysosplenetin (CHR) significantly augmented the rat plasma level and anti-malarial efficacy of artemisinin (ART), partially due to the uncompetitive inhibition effect of CHR on rat CYP3A. But the impact of CHR on P-gp is still unknown.

Objective: The present study investigates whether CHR interferes with P-gp-mediated efflux of ART and elucidates the underlying mechanism.

Materials and methods: P-gp-over-expressing Caco-2 cells were treated with ART (10?μM) or ART-CHR (1:2, 10:20?μM) in ART bidirectional transport experiment. ART concentration was determined by UHPLC-MS/MS method. Healthy male ICR mice were randomly divided into nine groups (n?=?6) including negative control (0.5% CMC-Na solution, 13?mL/kg), ART alone (40?mg/kg), verapamil (positive control, 40?mg/kg), ART-verapamil (1:1, 40:40?mg/kg), CHR alone (80?mg/kg), ART-CHR (1:0.1, 40:4?mg/kg), ART-CHR (1:1, 40:40?mg/kg), ART-CHR (1:2, 40:80?mg/kg) and ART-CHR (1:4, 40:160?mg/kg). The drugs were administrated intragastrically for seven consecutive days. MDR1 and P-gp expression levels in mice small intestine were examined by performing RT-PCR and western blot analysis. ABC coupling ATPase activity was also determined.

Results: After combined with CHR (1:2), P_app (AP-BL) and P_app (BL-AP) of ART changed to 4.29?×?10?^??⁸ (increased 1.79-fold) and 2.85?×?10?^??^8?cm/s (decreased 1.24-fold) from 2.40?×?10?^??⁸ and 3.54?×?10?^??^8?cm/s, respectively. Efflux ratio (P_BA/P_AB) declined 2.21-fold (p?p?p?Discussion and conclusion: These results confirm that CHR inhibited P-gp activity and reverse the up-regulated P-gp and MDR1 levels induced by ART. It suggested that CHR potentially can be used as a P-gp reversal agent to obstruct ART multidrug resistance.     

Toxic rather than neuropharmacological effect of Ternstroemia sylvatica fruits and identification of 28-O-[β-l-6-rhamnopyranosyl]-R1-barrigenol as a new compound with toxic effects in mice

Abstract

Context: Fruits of Ternstroemia sylvatica Schltdl. and Cham. (Theaceae) are used in Mexican traditional medicine to alleviate anxiety, sleep disorders and seizures; however, the active principles have not been identified.

Objective: To identify the neuroactive principles of T. sylvatica fruits using neuropharmacological tests on mice.

Materials and methods: The methanol and aqueous extracts of pericarp or seeds of T. sylvatica fruits were intraperitoneally administered (1–562?mg/kg, single doses) to mice. The exploratory cylinder, hole board, open field, Rota-rod and sodium pentobarbital-induced hypnosis tests were used to evaluate the CNS depressant effect after 30?min single administration of extracts. From aqueous seeds extract, triterpene glycoside 28-O-[β-l-6-rhamnopyranosyl]-R₁-barrigenol was isolated an active compound.

Results: Crude extracts of T. sylvatica fruits, separated from seed and pericarp, showed sedative effect in mice. The aqueous (ED₅₀?=?4.9?±?0.8?mg/kg) seed extracts is the most active among them. This extract also decrease locomotor activity and disrupt motor coordination of mice. This extract was also the most toxic extract (LD₅₀?=?5.0?±?1.4?mg/kg; i.p.). The triterpene glycoside 28-O-[β-l-6-rhamnopyranosyl]-R₁-barrigenol was identified in this extract as one of the active sedative compounds (ED₅₀?=?0.12?±?0.01?mg/kg) also with toxic effect (LD₅₀?=?1.11?±?0.23?mg/kg).

Conclusion: The results suggest that T. sylvatica fruits has toxic activity rather than CNS depressant activity in mice and that this effect might be related to the presence of 28-O-[β-l-6-rhamnopyranosyl]-R₁-barrigenol, one of the active principles of T. sylvatica fruits with sedative and toxic effect.     

Pharmacological evaluation of the anxiolytic-like effects of Lippia graveolens and bioactive compounds

Context: Lippia species (Verbenaceae) are widely used in Latin America and Africa as folk medicine for their tranquilizing properties.

Objective: To evaluate the anxiolytic-like effects and safety of Lippia graveolens Kunth. by exploring its aqueous and organic leaf extracts and identifying the responsible chemical constituents.

Material and methods: Aqueous and organic extracts (hexane, ethyl acetate and methanol) were pharmacologically evaluated at several doses. Chemical constituents were identified using MS, NMR and GC-MS analysis. The isolated compounds (3?mg/kg, i.p.), extracts (1, 3, 10 and 30?mg/kg, i.p.), and the reference drug diazepam (0.1?mg/kg, i.p.) were assessed in CD-1 mice using experimental behavioural models: open-field, cylinder, hole-board, plus-maze and sodium pentobarbital-induced hypnosis, as well as their acute toxicity (LD₅₀).

Results: After administration of the extracts and bioactive compounds, a significant anxiolytic-like response from 1?mg/kg, i.p. was observed, resembling the effect of diazepam. Major presence of thymol (33.40%) was observed in the hexane extract; whereas for the first time in this species a p-cymene?+?thymol mixture (9.78%), naringenin (0.18%) and cirsimaritin (1.16%) were obtained as bioactive constituents of the ethyl acetate crude extract. Acute toxicity was calculated to be LD₅₀ =?1000?mg/kg for the crude hexane extract, lower in comparison to the other extracts analyzed (LD₅₀ >?2000?mg/kg).

Discussion and conclusion: Our results suggest that L. graveolens exerts anxiolytic-like activity involving many kinds of constituents, mainly of the terpenoid and flavonoid nature. These results reinforce the potential use of this species in the therapy of anxiety.     

Novel GABAB receptor positive modulators: a patent survey

Importance of the field: Positive allosteric modulators of GABA_B receptors may have a similar potential as positive modulators of GABA_A receptors, the benzodiazepines discovered in 1957. The discovery of positive allosteric modulators of GABA_B receptors at Novartis in Basel in 2000 opened the way to search for compounds, which activate GABA_B receptors without the drawbacks of full agonists, such as desensitization, tolerance, muscle-relaxant effects, hypothermia, and central and gastrointestinal side effects.

Areas covered in this review: Numerous animal experiments point out that several indications can be addressed with positive modulators of GABA_B receptors, such as depression, anxiety, schizophrenia, neuropathic and chronic pain and treatment of craving for drugs of abuse, such as alcohol, cocaine and nicotine. Peripherally acting compounds may be valuable drugs for the treatment of gastroesophageal reflux disease and irritable bowel syndrome.

What the reader will gain: An overview on 19 patents in this field, of the different scaffolds for positive modulators of GABA_B receptors and of the major players in the field.

Take home message: The search for subtype selective benzodiazepine receptor ligands has proved to be extremely difficult. Positive modulators of GABA_B receptors may provide novel anxiolytic drugs faster.