GABA(A) receptor modulation and neuropharmacological activities of viscosine isolated from Dodonaea viscosa (Linn)

Exploring antioxidative, cytotoxic and neuropharmacological insights into Bixa orellana leaves: Experimental and in silico approaches

Background Study

The aim of this research was to examine possible antioxidant, cytotoxic and neurological activity of methanol and n-hexane extracts of Bixa orellana leaves. Additionally, we aimed to identify potential lead compounds through in-silico analysis.

Methods

In-vitro antioxidative properties were investigated through different assays, including: total phenolic content assay (TPC), total flavonoid content assay (TFC), DPPH free radical scavenging assay and reducing power assay. Also, the cytotoxic effect of the samples was assessed using the brine shrimp lethality test. In addition, anxiolytic, locomotor, and CNS depressant activities were assessed utilizing various established methods. Moreover, reported compounds were used in the in silico study to explore the best-fit phytoconstituents against gamma-aminobutyric acid (GABAA) receptor.

Results

MBOL displayed substantial antioxidative activities in various established assays compared to NBOL. In brine shrimp lethality bioassay, both MBOL and NBOL revealed cytotoxic activity in a concentration-dependent approach. Again, in Elevated Plus Maze test, 200 and 400 mg/kg of NBOL and MBOL demonstrated significant anxiolytic activities evident from time spent in open arms. In addition, maximum number of head dipping was demonstrated by MBOL at 400 mg/kg (53.90 ± 1.16) in Hole Board test. NBOL and MBOL at both doses significantly diminished the magnitude of movements from the 2nd to 5th observation periods in Open Field test. Furthermore, in Hole Cross test, MBOL remarkably dwindled the locomotor activity at 120 min and 180 min (3.60 ± 0.40 and 2.40 ± 0.51) at 400 mg/kg. Finally, in silico analysis revealed 13 compounds as promising leads with strong binding affinity to GABAA receptor along with good pharmacokinetics and toxicity profiles.

Conclusion

Therefore, the present study's findings advocate the traditional usage of this plant and recommend both MBOL and NBOL as as a potential source of therapeutic candidate for the management of neurological disorders.

Evaluation of 28-day repeated doses oral toxicity of essential oil from Psidium glaziovianum Kiaersk leaves on various biological parameters in Swiss mice

Only a small number of the many medicinally important species in the genus Psidium L. have had their safety assessed. Psidium glaziovianum, a plant native to Brazil, is reported to exert antinociceptive and anti-inflammatory effects; however, there are no apparent reports of long-term safety following administering of repeated doses. The aim of this study was to examine the effects of 28-day oral of treatment at 250, 500 or 1,000 mg/kg Psidium glaziovianum essential oil (PgEO) on behavioral and physiological parameters in male and female Swiss mice. First, PgEO was chemically characterized by gas chromatography mass spectrometry (GC-MS). The following parameters were examined: motor activity, body temperature, blood glucose, urine, hematology, biochemistry, histology, and oxidative stress. Characterization of PgEO revealed 48 components which were dominated by sesquiterpenes 1,8-cineol (24.29%), α-pinene (19.73%) and β-pinene (17.31%). Data showed that PgEO treatment in mice increased activities of antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT) without markedly affecting body weight, hematological or biochemical parameters, as well as water or food consumption. Administration of PgEO in repeated daily dosages over 28 days did not significantly alter exploratory or locomotor activities. Based upon our findings, PgEO administration daily for 28 days, exhibited low toxicity and absence of effects on the nervous system. Data demonstrated that PgEO produced hypoglycemic and antioxidant actions which need to be considered in safety assessment.

Hawaiian Plants with Beneficial Effects on Sleep, Anxiety, and Mood, etc

Diverse chemical messengers are responsible for maintaining homeostasis in the human body, for example, hormones and neurotransmitters. Various Hawaiian plant species produce compounds that exert effects on these messengers and the systems of which they are a part. The main purpose of this review article is to evaluate the potential effects of Hawaiian plants on reducing pain and anxiety and improving sleep and mood. A comprehensive literature search was conducted in SciFinder, PubMed, Science Direct, Scopus, Google Scholar, and Scientific Information Database between 2019 and 2023 to identify related articles. Results indicate that several Hawaiian plant species, such as M. citrifolia and P. methysticum, have medicinal properties associated with these effects. These plants have been used in traditional Hawaiian cultural practices for centuries, suggesting their potential to benefit human health and well-being. This review presents a comprehensive analysis of the available evidence concerning the potential impacts of Hawaiian plants on sleep, anxiety, mood, and pain.

Protective role of Dodonaea viscosa extract against streptozotocin-induced hepatotoxicity and nephrotoxicity in rats

Previous investigations have shown that D. viscosa herbal extract is often used to treat a variety of diseases. Therefore, the purpose of this study was to investigate any additional potential impacts on rat liver and kidney damage induced by diabetes. Streptozotocin (STZ) (60 mg/kg/day) was given as a single dosage to cause type 1 diabetes. After then, diabetic rats received oral doses of D. viscosa for four weeks at 150 and 300 mg/kg/day. Blood, liver, and kidney tissues were collected at the end of the treatment and examined. Analysis was made of the serum lipid profile, liver, and kidney functions, as well as blood biochemistry. Moreover, the levels of tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), interleukin-1 beta (IL-1β), prostaglandin E-2 (PGE-2), and nitric oxide (NO) were estimated in serum. In liver and kidney samples, thiobarbituric acid reactive substances (TBARs) and reduced glutathione (GSH), as well as the pro-inflammatory cytokines and enzymatic activities of glutathione peroxidase (GPx), glutathione reeducates (GR), glutathione-S-transferase (GST), catalase (CAT), and superoxide dismutase (SOD) were analyzed. Histological changes in liver and kidney cross-sections were also observed. Our findings demonstrated that D. viscosa dramatically decreased pro-inflammatory indicators in blood, kidney, and liver tissues as well as blood glucose, and restored insulin levels, and lipid profiles. Additionally, it significantly raises the antioxidant enzyme activity SOD, CAT, GPx, and GST, while significantly lowering TBARs levels. The above-mentioned biochemical changes that took place in tissues were further supported by histological alterations. These findings imply that D. viscosa protects against STZ-induced hyperglycemia, aberrant lipid synthesis, and oxidative stress and that these benefits may be mediated by interacting with various targets to increase the levels of antioxidant enzymes in the liver and kidneys. Its mode of action and safety for use as medicine against various metabolic problems caused by diabetes require more research.

Phenolics as GABAA Receptor Ligands: An Updated Review

Natural products can act as potential GABA modulators, avoiding the undesirable effects of traditional pharmacology used for the inhibition of the central nervous system such as benzodiazepines (BZD). Phenolics, especially flavonoids and phlorotannins, have been considered as modulators of the BZD-site of GABA_A receptors (GABA_ARs), with sedative, anxiolytic or anticonvulsant effects. However, the wide chemical structural variability of flavonoids shows their potential action at more than one additional binding site on GABA_ARs, which may act either negatively, positively, by neutralizing GABA_ARs, or directly as allosteric agonists. Therefore, the aim of the present review is to compile and discuss an update of the role of phenolics, namely as pharmacological targets involving dysfunctions of the GABA system, analyzing both their different compounds and their mechanism as GABAergic modulators. We focus this review on articles written in English since the year 2010 until the present. Of course, although more research would be necessary to fully establish the type specificity of phenolics and their pharmacological activity, the evidence supports their potential as GABA_AR modulators, thereby favoring their inclusion in the development of new therapeutic targets based on natural products. Specifically, the data compiled in this review allows for the directing of future research towards ortho-dihydroxy diterpene galdosol, the flavonoids isoliquiritigenin (chalcone), rhusflavone and agathisflavone (biflavonoids), as well as the phlorotannins, dieckol and triphlorethol A. Clinically, flavonoids are the most interesting phenolics due to their potential as anticonvulsant and anxiolytic drugs, and phlorotannins are also of interest as sedative agents.

5-O-methylcneorumchromone K Exerts Antinociceptive Effects in Mice via Interaction with GABAA Receptors

The proper pharmacological control of pain is a continuous challenge for patients and health care providers. Even the most widely used medications for pain treatment are still ineffective or unsafe for some patients, especially for those who suffer from chronic pain. Substances containing the chromone scaffold have shown a variety of biological activities, including analgesic effects. This work presents for the first time the centrally mediated antinociceptive activity of 5-O-methylcneorumchromone K (5-CK). Cold plate and tail flick tests in mice showed that the 5-CK-induced antinociception was dose-dependent, longer-lasting, and more efficacious than that induced by morphine. The 5-CK-induced antinociception was not reversed by the opioid antagonist naloxone. Topological descriptors (fingerprints) were employed to narrow the antagonist selection to further investigate 5-CK's mechanism of action. Next, based on the results of fingerprints analysis, functional antagonist assays were conducted on nociceptive tests. The effect of 5-CK was completely reversed in both cold plate and tail-flick tests by GABA_A receptor antagonist bicuculline, but not by atropine or glibenclamide. Molecular docking studies suggest that 5-CK binds to the orthosteric binding site, with a similar binding profile to that observed for bicuculline and GABA. These results evidence that 5-CK has a centrally mediated antinociceptive effect, probably involving the activation of GABAergic pathways.

Possible neuropharmacological effects of Adenia trilobata (Roxb.) in the Swiss albino mice model

Background

Known colloquially as akandaphal in Bangladesh, Adenia trilobata has some traditional uses. Its leaves and stems are extracted with pure methanol (MEATL, MEATS) and fractioned by n-hexane (NFATL, NFATS). The in vivo anxiolytic activity was evaluated by elevated plus maze (EPM) testing and hole-board test (HBT), whilst the locomotor activity was examined using the open-field test (OFT) and hole-cross test (HCT) and the antidepressant activity was assessed with the forced swimming test (FST) and the tail suspension test (TST).

Results

Regarding the anxiolytic activity, the 400-mg/kg doses of MEATL, NFATL, MEATS and NFATS exhibited maximum percentages of entry into the open arm of 33.85%, 32.23%, 30.06% and 41.84%, respectively, compare with the diazepam (69.33%). During HBT, MEATL (400 mg/kg) and NFATL (400 mg/kg) demonstrated 51.67 ± 0.88 and 57.67 ± 3.18 instances of head-dipping relative to diazepam (64.33 ± 3.16), whilst the locomotor activity showed a dose-dependent reduction in square movements and number of hole crossings. During FST and TST, the NFATL (400 mg/kg) exhibited rates of 43.32% and 57.71% time spent immobile, whilst fluoxetine experienced rates of 54.79% and 55.74%.

Conclusion

Adenia trilobata could be a potential component for the treatment of neuropharmacological defects. Further study is required.

Deciphering the Pharmacological Properties of Methanol Extract of Psychotria calocarpa Leaves by In Vivo, In Vitro and In Silico Approaches

The present study explores the neuropharmacological, antinociceptive, antidiarrheal, antioxidant, thrombolytic and cytotoxic activity of methanol extract of Psychotria calocarpa leaves (MEPC). In anxiolytic activity testing of MEPC by elevated plus maze test, hole-board test and light-dark test, the extract exhibited a dose-dependent reduction of anxiety while the open field test observed a decreased locomotion. The administration of MEPC revealed a significant dose-dependent reduction of depressant behavior in forced swimming and tail suspension test. Additionally, the antinociceptive and antidiarrheal activity exposed a significant reduction of nociception and diarrheal behavior at the highest dose. In addition, a strong antioxidant activity was observed in DPPH-free radical-scavenging assay (IC50 = 461.05 μg/mL), total phenol content (118.31 ± 1.12 mg) and total flavonoid content (100.85 ± 0.97 mg). The significant clot-lysis activity was also observed with moderate toxicity (LC50 = 247.92 μg/mL) level in the lethality assay of brine shrimp. Moreover, in silico molecular docking study showed that the compound Psychotriasine could offer promising active site interactions for binding proteins. Furthermore, ADME/T and toxicological properties of the compound satisfied the Lipinski's rule of five and Veber rules for drug-like potential and toxicity level. Overall, MEPC had a potential neuropharmacological, antinociceptive, antidiarrheal and antioxidant activity that warranted further investigation.

Anxiolytic-like activity of 5-methoxyflavone in mice with involvement of GABAergic and serotonergic systems - in vivo and in silico evidences

Anxiety disorders are common worldwide and novel compounds are investigated for anxiolytic effect. A few studies have demonstrated the anxiolytic-like activity of natural and synthetic flavonoids. 5-methoxyflavone, a synthetic flavone derivative, has been reported to exhibit central nervous system depressant (sedative-hypnotic) effect in an earlier study. The present study was designed to investigate whether 5-methoxyflavone possesses anxiolytic-like activity in mice by employing two unconditioned models of anxiety such as elevated plus maze and light-dark box test. The possible role played by GABAergic (GABA_A) and serotonergic (5HT_1A) systems in the anxiolytic-like effect of 5-methoxyflavone was also investigated in the elevated plus maze test. Molecular docking studies were performed to ascertain the interaction of 5-methoxyflavone with GABA_A (α₂ subunit-containing) and 5HT_1A receptors. 5-methoxyflavone treatment in mice (10, 20 or 40 mg/kg, i.p) increased the number of entries and time spent in the open arms in an elevated plus maze (p < 0.001). In the light-dark box test a significant increase in the time spent in light compartment (p < 0.001) and prolonged latency to enter the dark compartment (p < 0.01) were also observed. Pretreatment of mice with 5HT_1A antagonist pindolol (10 mg/kg, i.p) or GABA_A antagonist bicuculline (2 mg/kg, i.p) significantly attenuated the effect of 5-methoxyflavone in the elevated plus maze test. In silico studies provided evidences for good binding affinity of 5-methoxyflavone towards GABA_A (α₂ subunit-containing) and serotonergic (5HT_1A) receptors by H-bond interactions. In conclusion, the present study identified a novel anxiolytic-like effect of 5-methoxyflavone involving GABAergic and serotonergic mechanisms.

Psychopharmacological effects of riparin III from Aniba riparia (Nees) Mez. (Lauraceae) supported by metabolic approach and multivariate data analysis

Background

Currently there is a high prevalence of humor disorders such as anxiety and depression throughout the world, especially concerning advanced age patients. Aniba riparia (Nees) Mez. (Lauraceae), popular known as “louro”, can be found from the Amazon through Guianas until the Andes. Previous studies have already reported the isolation of alkamide-type alkaloids such as riparin III (O-methyl-N-2,6-dyhydroxy-benzoyl tyramine) which has demonstrated anxiolytic and antidepressant-like effects in high doses by intraperitoneal administration.

Methods

Experimental protocol was conducted in order to analyze the anxiolytic-like effect of riparin III at lower doses by intravenous administration to Wistar rats (Rattus norvegicus) (n = 5). The experimental approach was designed to last 15 days, divided in 3 distinct periods of five days: control, anxiogenic and treatment periods. The anxiolytic-like effect was evaluated by experimental behavior tests such as open field and elevated plus-maze test, combined with urine metabolic footprint analysis. The urine was collected daily and analyzed by ¹H NMR. Generated data were statistically treated by Principal Component Analysis in order to detect patterns among the distinct periods evaluated as well as biomarkers responsible for its distinction.

Results

It was observed on treatment group that cortisol, biomarker related to physiological stress was reduced, indicating anxiolytic-like effect of riparin III, probably through activation of 5-HT_2A receptors, which was corroborated by behavioral tests.

Conclusion

¹H NMR urine metabolic footprint combined with multivariate data analysis have demonstrated to be an important diagnostic tool to prove the anxiolytic-like effect of riparin III in a more efficient and pragmatic way.

Viscosine as a Potent and Safe Antipyretic Agent Evaluated by Yeast-Induced Pyrexia Model and Molecular Docking Studies

The antipyretic potential of viscosine, a natural product isolated from the medicinal plant Dodonaea viscosa, was investigated using yeast-induced pyrexia rat model, and its structure-activity relationship was investigated through molecular docking analyses with the target enzymes cyclooxygenase-1 (COX-1), cyclooxygenase-2 (COX-2), and microsomal prostaglandin E synthase-1 (mPGES-1). The in vivo antipyretic experiments showed a progressive dose-dependent reduction in body temperatures of the hyperthermic test animals when injected with viscosine. Comparison of docking analyses with target enzymes showed strongest bonding interactions (binding energy -17.34 kcal/mol) of viscosine with the active-site pocket of mPGES-1. These findings suggest that viscosine shows antipyretic properties by reducing the concentration of prostaglandin E₂ in brain through its mPGES-1 inhibitory action and make it a potential lead compound for developing effective and safer antipyretic drugs for treating fever and related pathological conditions.

Evidence for the involvement of a GABAergic mechanism in the effectiveness of natural and synthetically modified incensole derivatives in neuropharmacological disorders: A computational and pharmacological approach

In the course of our continuing exploration for novel bioactive lead compounds (s) from the species Boswellia, we have recently reported incensole derivatives isolated from Boswellia papyrifera Hochst. Given the known antidepressant-like effects of incensole and incensole acetate, we herein present that the low dose intraperitoneal administration of incensole derivatives, namely, incensfuran and incensone, showed significant antidepressant-like effects in the forced swim test (FST) and tail suspension test (TST). Furthermore, these compounds were evaluated for their anxiolytic potential in the elevated plus maze (EPM) and light dark box (LDB) tests and anticonvulsant effects in pentylenetetrazole (PTZ)-induced seizure tests. In the EPM test, administration of these compounds led to dose-dependent increases in open arm entries and in the time spent in EPM open arms. Similar results were obtained in the LDB test, wherein compounds these caused significant increases in the number of transitions between lit and dark compartments and the time spent in the lit compartment. The anxiolytic-like effects in the EPM were not reversed by pretreatment with flumazenil, whereas PTZ and bicuculline (BIC) completely abolished the anxiolytic effects, showing the involvement of the non-benzodiazepine binding sites of GABA_A receptors. All four compounds induced significantly elevated brain GABA levels, indicating the involvement of a GABAergic mechanism. Additionally, molecular docking was conducted to elucidate the mode of action for the anxiolytic and anticonvulsant effects of these derivatives. Moreover, these compounds also possess drug-like properties and excellent ADMET profiles.

Cytotoxic Flavonoids from the Aerial Parts of Stachys lavandulifolia Vahl

Background: Stachys lavandulifolia Vahl is a herbaceous plant distributed in the west and south western Asia. Despite of the wide medicinal uses, there are some reports on toxicity potential of this plant. In present study we attempted to evaluate the toxicity and to characterize the cytotoxic principles of S. lavandulifolia. Methods: Brine shrimp lethality test (BSLT) was used to evaluate the general toxicity of the extracts and essential oil obtained from the aerial parts of S. lavandulifolia. Phytochemical constituents of the active extract were investigated using various chromatographic and spectroscopic methods. GC and GC-MS were also used to analyze the plant essential oil. GC and GC-MS were used to analyze the plant essential oil. Cytotoxic activities of the isolated compounds were also evaluated using MTT assay method. Results: In brine shrimp lethality test (BSLT), chloroform extract and the plant essential oil exhibited the most toxicity against Artemia salina larvae (LD50: 121.8±5.6 and 127.6±14.7 µg ml-1, respectively). GC and GC-MS analyses of essential oil led to the characterization of forty compounds of which α-bisabolol (23.85%) and thymol (17.88%) were identified as the main constituents. Nine flavonoids, Pachypodol (1), chrysosplenetin (2), kumatakenin (3), velutin (4), penduletin (5), viscosine (6), chrysoeriol (7), hydroxygenkwanin (8) and apigenin (9) were isolated from the chloroform extract of S. lavandulifolia. Among the isolated compounds, chrysosplenetin (2), a polymethoxylated flavonoid, was found as the most toxic compound toward MDA-MB-23 and HT-29 cells, with IC50 values of 88.23 and 116.50 µg ml-1, respectively. Furthermore, chrysosplenetin (2), kumatakenin (3) and viscosine (6) with selectivity indices of 2.70, 2.59 and 3.33, respectively, showed higher preferential toxicity against MDA-MB-23 cells in comparison with tamoxifen (SI:2.45). Conclusion: This study reports methoxylated flavonoids as compounds which could be involved in toxicity of S. lavandulifolia. The results of MTT assay also suggest some of these compounds as appropriate candidates for anti-cancer drug development research.

Sedative-hypnotic like effect of 5-methoxyflavone in mice and investigation on possible mechanisms by in vivo and in silico methods

Flavonoids have been shown to possess central nervous system (CNS) depressant effect mediated through the ionotropic GABA_A receptors. In the present study, 5-methoxyflavone was evaluated for sedative-hypnotic like activity in mice and the mechanisms involved by employing a battery of tests including molecular docking studies. In the open field test, 5-methoxyflavone in various doses (50, 100 and 150 mg/kg, i.p) exhibited a significant and dose-dependent reduction in the spontaneous locomotor activity (F (530) = 87.17 P < 0.001). Pretreatment with 5-methoxyflavone decreased the latency to sleep induction after pentobarbitone or ether administration and also significantly increased the duration of sleep (p < 0.001). A significant and dose-dependent myorelaxant effect was observed with 5-methoxyflavone in the inclined plane, horizontal wire test and rota rod test. Pretreatment with picrotoxin, bicuculline, glycine, caffeine or NMDA either decreased or completely abolished the hypnotic effect of 5-methoxyflavone in mice. The above results revealed the involvement of GABA_A, adenosine, glycine and NMDA receptors in the hypnotic effect of 5-methoxyflavone. The results of in silico studies indicated that, 5-methoxyflavone exhibits good binding affinity towards these receptors by H-bond interactions. In conclusion, the present study identified a novel and potential sedative-hypnotic like effect of 5-methoxyflavone involving multiple mechanisms.

Nelumbo nucifera Seed Extract Promotes Sleep in Drosophila melanogaster

The sleep-promoting effects of the water extract of Nelumbo nucifera seeds (NNE) were investigated in an invertebrate model. The effects of NNE on the subjective nighttime activity, sleep episodes, and sleep time were determined using Drosophila melanogaster and locomotor activity monitoring systems in basal and caffeine-induced arousal conditions. The movements of fruit flies were analyzed using the Noldus EthoVision-XT system, and the levels of neuromodulators were analyzed using HPLC. Expression of neuromodulator receptors was analyzed using real-time PCR. NNE was shown to contain neurotransmission-related components; γ-aminobutyric acid (GABA) (2.33±0.22 mg/g), tryptophan (2.00±0.06 mg/g), quinidine (0.55±0.33 mg/g), and neferine (0.16±0.01 mg/g). The total activity of flies during nighttime was decreased by 52% with 1.0% NNE treatment. In the individual and collective conditions, the subjective nighttime activities (45/38%) and sleep bouts (20/14%) of flies was significantly decreased with NNE treatment, while total sleep times (10/27%) were significantly increased. This sleep-promoting effect is more pronounced in caffeine-treated conditions; the nighttime activity of flies was reduced by 53%, but total sleep time was increased by 60%. Our video-tracking analysis showed a significant decrease of the moving distance and velocity of flies by NNE. This NNE-mediated sleep-promoting effect was associated with up-regulation of GABA_A/GABA_B and serotonin receptors. The NNE-mediated increase of GABA content was identified in flies. These results demonstrate that NNE effectively promotes sleep in flies by regulating the GABAergic/serotonergic neuromodulators, and could be an alternative agent for sleep promotion.

Isolation and Characterization of Two New Secondary Metabolites From Quercus incana and Their Antidepressant- and Anxiolytic-Like Potential

The ethyl acetate fraction of Quercus incana yielded two new compounds [1 and 2]. The characterization and structure elucidation of these compounds were carried out through various spectroscopic techniques such as mass spectrometry along with one- and two-dimensional NMR techniques. The structural formula was deduced to be 2-(4-hydroxybutan-2-yl)-5-methoxyphenol [1] and 4-hydroxy-3-(hydroxymethyl) pentanoic acid [2]. The elevated plus maze (EPM) and light–dark box (LDB) tests (classical mouse models) were performed in order to reveal the anxiolytic potential of both compounds [1 and 2]. Both compounds displayed dose-dependent increases in open-arm entries and time spent in open arms in EPM (^∗P < 0.05, ^∗∗P < 0.01), and increased the time spent in the lit compartment and increased transitions between the two compartments in LDB test (^∗P < 0.05, ^∗∗P < 0.01). Co-administration of selective benzodiazepine (BZP) receptor antagonist, flumazenil (2.5 mg/kg) with compounds [1 and 2] decreased the anxiolytic-like activity of both compounds in the EPM indicating BZP-binding site of GABA-A receptors are involved in the anxiolytic-like effect. Similarly, both compounds at the dose level of 10 and 30 mg/kg, i.p. exerted pronounced antidepressant-like effect in both forced swimming as well as tail suspension tests (^∗P < 0.05, ^∗∗P < 0.01; ANOVA followed by Dunnett’s post hoc test). The effect at 30 mg/kg was comparable to the reference drug imipramine (60 mg/kg).

Clarified Açaí (Euterpe oleracea) Juice as an Anticonvulsant Agent: In Vitro Mechanistic Study of GABAergic Targets

Seizures affect about 50 million people around the world. Approximately 30% of seizures are refractory to the current pharmacological arsenal, so, the pursuit of new therapeutic alternatives is essential. Clarified Euterpe oleracea (EO) juice showed anticonvulsant properties similar to diazepam in an in vivo model with pentylenetetrazol, a GABA_A receptor blocker. This study investigated the effects of EO on the main GABAergic targets for anticonvulsant drugs, analyzing the effect on the GABA receptor's benzodiazepine and picrotoxinin binding sites and the GABA uptake. Primary cultures of cortical neurons and astrocytes were treated with EO (0–25%) for up to 90 min. [³H]Flunitrazepam and [³H]TBOB binding, [³H]GABA uptake, cell viability, and morphology were assayed. Nonlethal concentrations of EO increased agonist binding and decreased antagonist binding in cortical neurons. Low concentrations significantly inhibited GABA uptake, especially in astrocytes, suggesting an accumulation of endogenous GABA in the synaptic cleft. The results demonstrate, for the first time, that EO can improve GABAergic neurotransmission via interactions with GABA_A receptor and modulation of GABA uptake. Understanding these molecular mechanisms will help in the treatment of seizures and epilepsy, especially in developing countries where geographic isolation and low purchasing power are the main barriers to access to adequate treatment.

Achyranthes aspera Attenuates epilepsy in experimental animals: possible involvement of GABAergic mechanism

The present study was aimed to examine the possible anticonvulsant property of aerial parts of Achyranthes aspera using various experimental models of epilepsy in mice. Petroleum ether extract of aerial parts of A. aspera (PeAA), methanolic eAA (MeAA) and aqueous eAA (AeAA) was initially evaluated against six-hertz seizure model in mice, based on the outcomes the effective extract was further evaluated against maximal electroshock (MES) and pentylenetetrazole (PTZ) models in mice. In addition, the potent extract was evaluated against the PTZ model by co-administering with flumazenil (FMZ), and also evaluated for its effect on GABA levels in brain and NMDA-induced lethality in mice. Furthermore, the probable locomotor deficit-inducing property of the extract was evaluated by actophotometer test in mice. In results, only MeAA showed protection against six-hertz-induced seizures in mice, based on these outcomes only MeAA was evaluated in MES and PTZ models. Notably, the MeAA (200, 400 and 800 mg/kg) has offered mild and dose dependent protection against MES and PTZ-induced seizures in mice. Alongside, the MeAA (400 mg/kg) showed a significant increase in GABA levels in the brain compared to control, and in line with these findings the anti-PTZ effect of MeAA (400 mg/kg, p.o.) was blocked when co-administered with flumazenil (5 mg/kg, i.p.). However, the MeAA has not shown significant protection against NMDA-induced mortality and also did not cause significant change in locomotor activity compared to before treatment. These findings suggest that MeAA possess mild anticonvulsant activity and the outcomes further confirmed the involvement of GABAergic mechanism behind the anticonvulsant activity of MeAA.

Effects of picrotoxin on zebrafish larvae behaviors: A comparison study with PTZ

Larval zebrafish (Danio rerio) have been suggested as a high-throughput experimental animal model for epilepsy-related genetic and developmental studies. The behavioral manifestations in response to the seizure-inducing drugs picrotoxin (PTX) (1, 5, 25, 125, or 625μM) or pentylenetetrazole (PTZ) (1, 2, 4, 8, or 16mM) under light-dark conditions were studied using zebrafish larvae at 5days post-fertilization (dpf). Two behavioral parameters, locomotor activity and thigmotaxis behavior, were analyzed. We conclude that high concentrations of PTX treatment increased locomotion and thigmotaxis in 5 dpf zebrafish larvae under continuous illumination and the locomotion of PTX-treated zebrafish was decreased under the dark condition. High concentrations of PTX treatment also increased thigmotaxis (an indicator of increased anxiety levels) in zebrafish larvae under both continuous illumination and dark condition. PTZ treatment increased the locomotion of 5 dpf zebrafish larvae under continuous illumination. However, 2mM PTZ decreased locomotion, and high concentrations of PTZ decreased the locomotion of larvae under dark conditions. High concentrations of PTZ treatment also increased thigmotaxis in the zebrafish larvae under both continuous illumination and dark condition. Compared with PTZ, PTX leads to higher levels of movement under light conditions and lower levels of movement under dark condition. However, the level of thigmotaxis in the zebrafish larvae was similar between the two drug treatments.

Ameliorative potential of Colebrookea oppositifolia methanolic root extract against experimental models of epilepsy: Possible role of GABA mediated mechanism

BACKGROUND

Colebrookea oppositifolia Smith is one of the commonly used plants to treat epilepsy by various folk medicine communities like nomadic Gujjars, Tharu and Bhoxa in sub-Himalayan regions of India.

PURPOSE

The present study was undertaken to evaluate the anticonvulsant activity of roots of Colebrookea oppositifolia using various experimental models of epilepsy in mice.

METHODS

Petroleum ether extract of roots of C. Oppositifolia (PeCO), methanolic eCO (MeCO) and aqueous eCO (AeCO) was initially evaluated in six-hertz-seizure test in mice, the effective extract was further evaluated against maximal electroshock (MES) and pentylenetetrazole (PTZ) models in mice. In addition, the potent extract was evaluated against the PTZ model by co-administering with flumazenil (FMZ), and also evaluated for its effect on brain GABA levels in brain and NMDA-induced lethality in mice. Furthermore, the possible locomotor deficit-inducing property of the extract was evaluated by actophotometer test in mice.

RESULTS

In six-hertz-seizure test the MeCO (25, 50, 100 and 200mg/kg) and AeCO (50, 100, 200, 400 and 800mg/kg) showed significant protection compared to control group, and MeCO was more potent than AeCO. Based on these outcomes, only MeCO was evaluated in MES and PTZ models. Notably, the MeCO (25, 50, 100 and 200mg/kg) has offered significant and dose- dependent protection against MES and PTZ-induced seizures in mice. Alongside, the MeCO (100 and 200mg/kg) showed a significant increase in GABA levels in the brain compared to control. In line with these findings, the anti-PTZ effect of MeCO (100mg/kg, p.o.) was blocked when co-administered with flumazenil (3mg/kg, i.p.),and in NMDA-induced mortality test, the MeCO has shown only 50% protection at 200mg/kg dose, thus confirmed the significant role of GABA pathway. Interestingly, the MeCO did not cause significant change in locomotor activity compared to before treatment.

CONCLUSION

These findings suggest that MeCO possess significant anticonvulsant activity and the outcomes further confirmed the involvement of GABAergic mechanisms behind the anticonvulsant activity of MeCO.

Evaluation of anti-epileptic activity of leaf extracts of Punica granatum on experimental models of epilepsy in mice

Objectives:

This study was aimed to examine the anti-epileptic activity of leaf extracts of Punica granatum in experimental models of epilepsy in Swiss albino mice.

Materials and Methods:

Petroleum ether leaf extract of P. granatum (PLPG), methanolic LPG (MLPG), and aqueous LPG (ALPG) extracts of P. granatum leaves was initially evaluated against 6-Hz-induced seizure model; the potent extract was further evaluated against maximal electroshock (MES) and pentylenetetrazole (PTZ)-induced convulsions. Further, the potent extract was evaluated for its influence on Gamma amino butyric acid (GABA) levels in brain, to explore the possible mechanism of action. In addition, the potent extract was subjected to actophotometer test to assess its possible locomotor activity deficit inducing action.

Results:

In 6-Hz seizure test, the MLPG has alleviated 6-Hz-induced seizures significantly and dose dependently at doses 50, 100, 200, and 400 mg/kg. In contrast, PLPG and ALPG did not show any protection, only high dose of ALPG (400 and 800 mg/kg, p.o.) showed very slight inhibition. Based on these observations, only MLPG was tested in MES and PTZ models. Interestingly, the MLPG (50, 100, 200 and 400 mg/kg) has offered significant and dose-dependent protection against MES (P < 0.01) and PTZ-induced (P < 0.01) seizures in mice. Further, MLPG showed a significant increase in brain GABA levels (P < 0.01) compared to control and showed insignificant change in locomotor activity in all tested doses (100, 200 and 400 mg/kg). Interestingly, higher dose of MLPG (400 mg/kg, p.o.) and Diazepam (5 mg/mg, p.o.) have completely abolished the convulsions in all the anticonvulsant tests.

Conclusion:

These findings suggest that MLPG possesses significant anticonvulsant property, and one of the possible mechanisms behind the anticonvulsant activity of MLPG may be through enhanced GABA levels in the brain.

Hepatoprotective activity of viscosine is mediated by attenuation of hepatic macrophages and iNOS expression in CCl4-intoxicated rats

This study investigated the molecular mechanism(s) of the protective effects of a C-alkylated flavonoid, viscosine on an animal model of CCl₄-induced hepatotoxicity. Viscosine at 20, 50 and 100 mg kg^-1 was orally administered in a dose dependent manner per day for 3 days before the CCl₄ (1 : 1 v/v in olive oil, 1 ml kg^-1) treatment and 2 days after the treatment. Hepatoprotection was assessed in terms of reduction in serum enzyme activities (ALT, AST, and ALP) that occur after CCl₄ injury, and by histopathology and immunohistochemistry. The rise in serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase (ALP) in CCl₄-intoxicated rats was markedly suppressed by viscosine in a concentration dependent manner. The decrease in the activity of hepatic antioxidant enzyme, SOD, was significantly prevented by viscosine, likewise gradually the levels of MDA and GSH were also normalized compared to silymarin. Viscosine also reduced the CCl₄-induced damaged area from 2% to 0% as assessed by histopathology and prevented the mixed inflammatory infiltrate. Viscosine attenuated the inflammation in the liver around the injured central vein region by downregulating the CCl₄ induced activation of hepatic CD68+ macrophages, thereby reducing their number as well. The expression of inducible nitric oxide synthase (iNOS) was more potentially suppressed by viscosine compared to the FDA approved positive control silymarin. The results of this study indicate that viscosine could be effective in protecting the liver from acute CCl₄-induced injury. The hepatoprotective mechanisms of viscosine may be related to the free radical scavenging and attenuation of oxidative stress, as well as to the inhibition of inflammatory response in the liver. Here, we are proposing a novel mechanism of action of viscosine and suggesting that it may be a safe and better in vivo antioxidant.

GABA-A Receptor Modulation and Anticonvulsant, Anxiolytic, and Antidepressant Activities of Constituents from Artemisia indica Linn

Artemisia indica, also known as “Mugwort,” has been widely used in traditional medicines. However, few studies have investigated the effects of nonvolatile components of Artemisia indica on central nervous system's function. Fractionation of Artemisia indica led to the isolation of carnosol, ursolic acid, and oleanolic acid which were evaluated for their effects on GABA-A receptors in electrophysiological studies in Xenopus oocytes and were subsequently investigated in mouse models of acute toxicity, convulsions (pentylenetetrazole induced seizures), depression (tail suspension and forced swim tests), and anxiety (elevated plus maze and light/dark box paradigms). Carnosol, ursolic acid, and oleanolic acid were found to be positive modulators of α1β2γ2L GABA-A receptors and the modulation was antagonized by flumazenil. Carnosol, ursolic acid, and oleanolic acid were found to be devoid of any signs of acute toxicity (50–200 mg/kg) but elicited anticonvulsant, antidepressant, and anxiolytic activities. Thus carnosol, ursolic acid, and oleanolic acid demonstrated CNS activity in mouse models of anticonvulsant, antidepressant, and anxiolysis. The anxiolytic activity of all three compounds was ameliorated by flumazenil suggesting a mode of action via the benzodiazepine binding site of GABA-A receptors.