Flavonoids as GABAA receptor ligands: the whole story?

Effects of Viola odorata syrup on sleep quality in menopausal women: a randomized, triple-blind, controlled trial

PURPOSE

The present study aimed to assess the effects of Viola odorata syrup on the sleep quality of postmenopausal women.

METHODS

This triple-blinded randomized clinical trial was conducted on menopausal women presenting to the healthcare centers in Mashhad, Iran, in 2019. The participants were selected using simple random sampling. Participants received 5 ml syrup V. odorata or placebo twice a day for 1 month. Data were collected using the Pittsburgh Sleep Quality Index. The data were analyzed using SPSS version 25.

RESULTS

The 118 eligible women enrolled in the study were divided into two groups of V. odorata syrup and placebo (n = 59 each). The analysis was conducted on only 84 menopausal women (42 in each group) due to exclusions. Exclusions consisted of 12 participants who withdrew from the study due to unwillingness to cooperate, 8 who had irregular consumption of the therapeutic syrup, 6 with inaccurate completion of the questionnaire, and 8 due to lack of accessibility. The two study groups were homogenous in terms of demographic characteristics. Before the intervention, no significant difference was observed in the mean PSQI score between the two groups (9.2 ± 2.9 vs. 8.4 ± 2.5) (P = 0.18). However, a significant difference was seen in the mean PSQI score between the two groups (4.9 ± 1.9 vs. 8.1 ± 2.1, P < 0.001) after the intervention.

CONCLUSIONS

The findings of this study suggest that V. odorata syrup may be a useful therapeutic agent to improve the sleep quality of menopausal women.

REGISTRATION CODE

IRCT20180514039660N1.

Edible Herbal Medicines as an Alternative to Common Medication for Sleep Disorders: A Review Article

Insomnia is repeated difficulty in falling asleep, maintaining sleep, or experiencing lowquality sleep, resulting in some form of daytime disturbance. Sleeping disorders cause daytime fatigue, mental confusion, and over-sensitivity due to insufficient recovery from a sound sleep. There are some drugs, such as benzodiazepines and anti-histaminic agents, which help to sleep induction and insomnia cure. However, the prolonged administration is unsuitable because of tolerance and dependence. Therefore, the researchers attempt to find new medicines with lesser adverse effects. Natural products have always been good sources for developing new therapeutics for managing diseases such as cancer, cardiovascular disease, diabetes, insomnia, and liver and renal problems. Ample research has justified the acceptable reason and relevance of the use of these herbs in the treatment of insomnia. It is worth noting that in this study, we looked into various Persian herbs in a clinical trial and in vivo to treat insomnia, such as Artemisia annua, Salvia reuterana, Viola tricolor, Passiflora incarnata, lettuce, and Capparis spinose. According to research, herb extracts and fractions, particularly n-butanol fractions with non-polar agents, impact the benzodiazepine receptors and have hypnotic properties. Also, alkaloids, glycosides, flavonoids, saponins, and tannins in practically every plant are mentioned making them the popular natural compounds to help with sleep disorders and promote calmness.

Pharmacokinetic and pharmacodynamic herb-drug interactions-part I. Herbal medicines of the central nervous system

Unlike conventional drug substances, herbal medicines are composed of a complex of biologically active compounds. Therefore, the potential occurrence of herb-drug interactions is even more probable than for drug-drug interactions. Interactions can occur on both the pharmacokinetic and pharmacodynamic level. Herbal medicines may affect the resulting efficacy of the concomitantly used (synthetic) drugs, mainly on the pharmacokinetic level, by changing their absorption, distribution, metabolism, and excretion. Studies on the pharmacodynamic interactions of herbal medicines and conventional drugs are still very limited. This interaction level is related to the mechanism of action of different plant constituents. Herb-drug interactions can cause changes in drug levels and activities and lead to therapeutic failure and/or side effects (sometimes toxicities, even fatal). This review aims to provide a summary of recent information on the potential drug interactions involving commonly used herbal medicines that affect the central nervous system (Camellia, Valeriana, Ginkgo, Hypericum, Humulus, Cannabis) and conventional drugs. The survey databases were used to identify primary scientific publications, case reports, and secondary databases on interactions were used later on as well. Search keywords were based on plant names (botanical genera), officinal herbal drugs, herbal drug preparations, herbal drug extracts.

Flavonoids: the use in mental health and related diseases

Given the current increase in mental and neurological disorders, there is an urgent need to develop alternative treatments for patients. Flavonoids exhibit diverse biological activities, including antioxidant, anti-inflammatory and neuroprotective, and has been considered potential therapies for central nervous system diseases, such as Alzheimer's disease, Parkinson's disease, drug addiction, and stroke. Studies have shown that flavonoids protect neurons from oxidative stress, reduce inflammation, improve brain blood flow and enhance cognitive function. Moreover, its modulation of neurotransmission, such as GABAergic, dopaminergic, serotoninergic, and noradrenergic, has been studied for the treatment of mental disorders that require sedative effects, antidepressants, sleep inducers and anxiety reduction. Although more research is needed to fully understand the mechanisms and potential benefits of these compounds, the use of flavonoids for neurological diseases is a promising avenue for future research and development. This review focuses on major flavonoid subclasses and their applications in central nervous system disorders.

The Aqueous Lyophilisate of Alchemilla Kiwuensis Engl. (Rosaceae) Displays Antiepileptogenic and Antiepileptic Effects on PTZ-induced Kindling in rats: Evidence of Modulation of Glutamatergic and GABAergic Pathways Coupled to Antioxidant Properties

Alchemilla kiwuensis Engl. (Rosaceae) (A. kiwuensis) is an herbaceous plant traditionally used by Cameroonians to treat epilepsy and other central nervous system disorders. The present study evaluated the antiepileptogenic and antiepileptic effects of A. kiwuensis (40 mg/kg, 80 mg/kg) following Pentylenetetrazole (PTZ)-induced kindling as well as its sub-chronic toxicity. Following an initial i.p administration of a challenge dose (70 mg/kg), Wistar rats of both sexes received sub convulsive doses (35 mg/kg) of PTZ every other day, one hour after the oral gavage of animals with treatments, until two consecutive stage 4, in all animals of negative control. Seizure progression, latency, duration, and repetition were noted. Twenty-four hours later, animals were dissected to extract their hippocampi. The resulting homogenates were used to evaluate Malondialdehyde, reduced glutathione, catalase activity, GABA, GABA-Transaminase, glutamate, glutamate transporter 2, IL-1β and TGF-1 β. Sub-chronic toxicity was conducted according to OECD 407 guidelines. The lyophilisate of A. kiwuensis significantly increased the latency of seizure appearance, delayed seizure progression and decreased seizure repetition and duration. Biochemical analysis revealed that the lyophilisate significantly increased the catalase activity, reduced glutathione, GABA, glutamate transporter 2 and TGF-1B levels. The lyophilisate equally caused a significant decreased in the GABA-Transaminase activity, malondialdehyde, and IL-1 β levels. There was no noticeable sign of toxicity. A. kiwuensis possesses antiepileptic and antiepiletogenic effects by enhancing GABAergic neurotransmission and antioxidant properties, coupled to modulation of glutamatergic and neuroinflammatory pathways and is innocuous in a sub-chronic model. These justifies its local use for the treatment of epilepsy.

Application of gabapentinoids and novel compounds for the treatment of benzodiazepine dependence: the glutamatergic model

BACKGROUND

Current approaches for managing benzodiazepine (BZD) withdrawal symptoms are daunting for clinicians and patients, warranting novel treatment and management strategies. This review discusses the pharmacodynamic properties of BZDs, gabapentinoids (GBPs), endozepines, and novel GABAergic compounds associated with potential clinical benefits for BZD-dependent patients. The objective of this study was to review the complex neuromolecular changes occurring within the GABAergic and glutamatergic systems during the BZD tolerance and withdrawal periods while also examining the mechanism by which GBPs and alternative pharmacological therapies may attenuate withdrawal symptoms.

METHODS AND RESULTS

An elaborative literature review was conducted using multiple platforms, including the National Center for Biotechnology (NCBI), AccessMedicine, ScienceDirect, pharmacology textbooks, clinical trial data, case reports, and PubChem. Our literature analysis revealed that many distinctive neuroadaptive mechanisms are involved in the GABAergic and glutamatergic systems during BZD tolerance and withdrawal. Based on this data, we hypothesize that GBPs may attenuate the overactive glutamatergic system during the withdrawal phase by an indirect presynaptic glutamatergic mechanism dependent on the α₂δ₁ subunit expression.

CONCLUSIONS

GBPs may benefit individuals undergoing BZD withdrawal, given that the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor current significantly increases during abrupt BZD withdrawal in animal studies. This may be a conceivable explanation for the effectiveness of GBPs in treating both alcohol withdrawal symptoms and BZD withdrawal symptoms in some recent studies. Finally, natural and synthetic GABAergic compounds with unique pharmacodynamic properties were found to exert potential clinical benefits as BZD substitutes in animal studies, though human studies are lacking.

GABAA and serotonergic receptors participation in anxiolytic effect of chalcones in adult zebrafish

The prevalence of anxiety is a significant public health problem, being the 24th leading cause of disability in individuals affected by this disorder. In this context, chalcones, a flavonoid subclass obtained from natural or synthetic sources, interact with central nervous system (CNS) receptors at the same binding site as benzodiazepines, the primary drugs used in the treatment of anxiety. Thus, our study investigates the anxiolytic effect of synthetic chalcones derived from the natural product 2-hydroxy-3,4,6-trimethoxyacetophenone isolated from Croton anisodontus Müll.Arg. in modulating anxiolytic activity via GABAergic and serotoninergic neurotransmission in an adult zebrafish model. Chalcones 1 and 2 were non-toxic to adult zebrafish and showed anxiolytic activity via GABAA receptors. Chalcone 2 also had its anxiolytic action reversed by the antagonist granisetron, indicating the participation of serotonergic receptors 5HTR3A/3B in the anxiolytic effect. In addition, molecular docking results showed that chalcones have a higher affinity for the GABAA receptor than DZP and binding in the same region of the DZP binding site, indicating a similar effect to the drug. Furthermore, the interaction of chalcones with GABAA and 5-HT3A receptors demonstrates the anxiolytic effect potential of these molecules.Communicated by Ramaswamy H. Sarma.

Medicinal Plants Used for Anxiety, Depression, or Stress Treatment: An Update

Depression, anxiety, stress, and other mental disorders, which are on the rise worldwide, are indications that pharmacological therapy can have serious adverse effects, which is why many patients prefer to use herbal products to treat these symptoms. Here, we reviewed plants and products derived from them that are commonly used for the above indications, focusing on clinical data and safety profiles. While lavender, hops, maypop, lemon balm, and valerian have consistently been shown in clinical trials to relieve mild forms of neurological disorders, particularly depression, anxiety, and stress, currently available data do not fully support the use of peppermint for anxiety disorders and depression. Recent studies support the use of saffron for depression; however, its toxicological profile raises safety concerns. St. John’s wort is effective in alleviating mild to moderate depression; however, careful use is necessary particularly due to possible interactions with other drugs. In conclusion, more studies are needed to validate the mechanism of action so that these plants can be used successfully and safely to alleviate or eliminate various mental disorders.

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.

Effect of Hydroalcoholic Extract of Stachys lavandulifolia on Pentylenetetrazole-induced Seizures in Male Mice: The Role of GABAergic and Opioidergic Systems

Introduction

Epilepsy is one of the most common neurological disorders. Though there are several effective drugs for treating epilepsy, most drugs are associated with side effects and drug interactions. Stachys lavandulifolia used in Iranian traditional medicine has proven anti-anxiety and sedative properties. The current study aimed to evaluate the anticonvulsant effect of hydroalcoholic extract of S. lavandulifoliaon the Pentylenetetrazole (PTZ)-induced seizure in male mice and the role of benzodiazepine and opioid receptors.

Methods

This study was conducted on 100 male mice, randomly categorized into 10 groups: Normal Saline (NS), two diazepam groups (0.025 and 0.1 mg/kg), three S. lavandulifolia extract groups (50, 100, and 200 mg/kg), diazepam 0.025 mg/kg+S. lavandulifolia extract 50 mg/kg, and three groups that pretreated with NS, flumazenil, or naloxone, 5 min before injection of 200 mg/kg S. lavandulifolia extract. After 30 min, PTZ (80 mg/kg) was injected into animals, and seizure indices were evaluated.

Results

The S. lavandulifoliaextract attenuated the PTZ-induced seizures in a dose-dependent manner, and pretreatment with flumazenil reversed this effect. However, pretreatment with naloxone could not reverse this effect because seizure indices in the naloxone pretreated group were lower than that in the normal saline group. The combination of an ineffective dose of diazepam and S. lavandulifoliaextract decreased PTZ-induced seizures.

Conclusion

The results of our study showed the anticonvulsant properties of hydroalcoholic extract of S. lavandulifolia. These effects might be due to the impact of the components of this extract on the central benzodiazepine system.

Highlights

Hydroalcoholic extract of S. lavandulifolia attenuated the PTZ-induced seizures in a dose dependent manner.Pretreatment with flumazenil (blocker of benzodiazepines receptor) reversed anti-seizure effect of S. lavandulifolia extract.Combination of an ineffective dose of diazepam and S. lavandulifolia extract decreased PTZ-induced seizures.

Plain Language Summary

Epilepsy is one of the most common neurological disorders after stroke and is characterized by recurrent seizures due to abnormal excessive neural activity in the brain. Although there are many anticonvulsant drugs on the market, not all patients with epilepsy can be treated and one-third of patients suffer from recurring epilepsy despite using different antiepileptic drugs and more than 50% of them show side effects drugs during treatment. So, it is necessary to conduct further studies to develop more effective anti-epilepsy drugs with the minimum side effects. In recent years, plenty of studies have been conducted on medical plants, and S. lavandulifolia reported among the Iranian traditional medicine with antianxiety and sedative features. Some studies have mentioned the sedative and anti-inflammatory function of S. lavandulifolia, and its significant effects on anxiety have been approved comparable to diazepam. Overall, considering the anti-anxiety, analgesic, and sedative effects of the hydroalcoholic extract of S. lavandulifolia, it might possess anti-convulsive effects, too. The purpose of the current study was designed to investigate whether the effect of intra peritoneal injection of hydroalcoholic extract of S. lavandulifolia on the PTZ-induced convulsion in male mice and assessed the role of benzodiazepine and opioid receptors. Results of this study demonstrated that S. lavandulifolia extract attenuated the PTZ-induced seizures in a dose dependent manner, and pretreatment with flumazenil (blocker of benzodiazepines receptor) reversed this effect. However, pretreatment with naloxone (Non-selective blocker of opioids receptor) could not reverse this effect but the combination of an ineffective dose of diazepam and S. lavandulifolia extract decreased PTZ-induced seizures, thus anti-epileptic effect of S. lavandulifolia mediated by benzodiazepine receptors.

Modulation of recombinant human alpha 1 glycine receptor by flavonoids and gingerols

The inhibitory glycine receptor (GlyR) is a principal mediator of fast synaptic inhibition in mammalian spinal cord, brainstem, and higher brain centres. Flavonoids are secondary plant metabolites that exhibit many beneficial physiological effects, including modulatory action on neuronal receptors. Using whole-cell current recordings from recombinant human α1 GlyRs, expressed in HEK293 cells, we compared the flavonols kaempferol and quercetin, the flavanone naringenin, the flavones apigenin and nobiletin, the isoflavone genistein, and two gingerols, 6-gingerol and 8-gingerol for their modulation of receptor currents. All compounds were inhibitors of the GlyR with IC₅₀ values ranging between 9.3 ± 2.6 µM (kaempferol) and 46.7 ± 6.5 µM (genistein), following a mixed mode of inhibition. Co-application of two inhibitors revealed distinct binding sites for flavonoids and gingerols. Pore-lining mutants T258A and T258S were strongly inhibited by quercetin and naringenin, but not by 6-gingerol, confirming the existence of distinct binding sites for flavonoids and gingerols. Apigenin, kaempferol, nobiletin, naringenin and 6-gingerol showed biphasic action, potentiating glycine-induced currents at low concentration of both, modulator and glycine, and inhibiting at higher concentrations. Identification of distinct modulatory sites for flavonoids and related compounds may present pharmacological target sites and aid the discovery of novel glycinergic drugs.

Natural Medicines for the Treatment of Epilepsy: Bioactive Components, Pharmacology and Mechanism

Epilepsy is a chronic disease that can cause temporary brain dysfunction as a result of sudden abnormal discharge of the brain neurons. The seizure mechanism of epilepsy is closely related to the neurotransmitter imbalance, synaptic recombination, and glial cell proliferation. In addition, epileptic seizures can lead to mitochondrial damage, oxidative stress, and the disorder of sugar degradation. Although the mechanism of epilepsy research has reached up to the genetic level, the presently available treatment and recovery records of epilepsy does not seem promising. Recently, natural medicines have attracted more researches owing to their low toxicity and side-effects as well as the excellent efficacy, especially in chronic diseases. In this study, the antiepileptic mechanism of the bioactive components of natural drugs was reviewed so as to provide a reference for the development of potential antiepileptic drugs. Based on the different treatment mechanisms of natural drugs considered in this review, it is possible to select drugs clinically. Improving the accuracy of medication and the cure rate is expected to compensate for the shortage of the conventional epilepsy treatment drugs.

2-Aminoimidazoles as potent inhibitors of contaminating brewery biofilms

Cleaning and disinfection protocols are not always able to remove biofilm microbes present in breweries, indicating that novel anti-biofilm strategies are needed. The preventive activities of three in-house synthesized members of the 2-aminoimidazole class of anti-biofilm molecules were studied against 17 natural brewery biofilms and benchmarked against 18 known inhibitors. Two 2-aminoimidazoles belonged to the top six inhibitors, which were retested against 12 defined brewery biofilm models. For the three best inhibitors, tannic acid (n° 1), 2-aminoimidazole imi-AAC-5 (n° 2), and baicalein (n° 3), the effect on the microbial metabolic activity was evaluated. Here, the top three inhibitors showed similar effectiveness, with baicalein possessing a slightly higher efficacy. Even though the 2-aminoimidazole was the second-best inhibitor, it showed a lower biocidal activity than tannic acid, making it less prone to resistance evolution. Overall, this study supports the potential of 2-aminoimidazoles as a preventive anti-biofilm strategy.

The role of hippocampal GABAA receptors on anxiolytic effects of Echium amoenum extract in a mice model of restraint stress

Echium amoenum (EA), a popular medicinal plant in Persian medicine, has anxiolytic, antioxidant, sedative, and anti-inflammatory effects. This study examined whether GABA-ergic signaling is involved in the anxiolytic effects of EA in mice. Sixty BALB/c mice (25-30 g) were divided into six groups (n = 10) as follows: the (I) control group received 10 ml/kg normal saline (NS). In the stress groups, the animals underwent 14 consecutive days of restraint stress (RS), and received following treatments simultaneously; (II) RS + NS; (III) RS + Diaz (Diazepam); (IV) RS + EA; (V) RS + Flu (Flumazenil) + EA; (VI) RS + Flu + Diaz. Behavioral tests including the open field test (OFT) and elevated plus maze (EPM) were performed to evaluate anxiety-like behaviors and the effects of the regimens. The plasma level of corticosterone and the hippocampal protein expressions of IL-1β, TNF-α, CREB, and BDNF, as well as p-GABA_A/GABA_A ratio, were also assessed. The findings revealed that chronic administration of EA alone produced anxiolytic effects in both behavioral tests, while diazepam alone or in combination with Flu failed to decrease the anxiety-like behaviors. Furthermore, the p-GABA_A/GABA_A and p-CREB/CREB ratios, and protein levels of BDNF were significantly increased in the EA-received group. On the other hand, plasma corticosterone levels and the hippocampal IL-1β and TNF-α levels were significantly decreased by EA. However, pre-treatment with GABA_A receptors (GABA_A Rs) antagonist, Flu, reversed the anxiolytic and molecular effects of EA in the RS-subjected animals. Our findings confirmed that alternation of GABA_AR is involved in the effects of EA against RS-induced anxiety-like behaviors, HPA axis activation, and neuroinflammation.

Herbal Medicinal Products from Passiflora for Anxiety: An Unexploited Potential

Herbal medicines containing Passiflora species have been widely used to treat anxiety since ancient times. The species Passiflora incarnata L. is included in many Pharmacopoeias, and it is the most used species in food, cosmetic, and pharmaceutical industries. However, there are around 600 species of the genus Passiflora and probably other species that can be used safely. Thus, this article was based on a search into the uses of the main species of the genus Passiflora with anxiolytic activity and its main secondary metabolites and some pharmacological studies, patents, and registered products containing Passiflora. Furthermore, the Brazilian Regulatory Health Agency Datavisa, Medicines and Healthcare Products Regulatory Agency of the United Kingdom, and the European Medicines Agency websites were consulted. The results showed that Passiflora species have health benefits but clinical trials are still scarce. The complexity of Passiflora extracts creates challenges for the development of herbal medicines. P. incarnata is the most studied species of the genus and the most used in natural anxiolytic herbal medicine formulations. However, there are hundreds of Passiflora species potentially useful for medicinal and nutraceutical purposes that are still little explored.

Neuroprotective Polyphenols: A Modulatory Action on Neurotransmitter Pathways

BACKGROUND

Balance in neurotransmission is essential for the proper functioning of the nervous system and even a small, but prolonged disturbance, can induce the negative feedback mechanisms leading to various neuropathologies. Neurodegenerative and mood disorders such as Alzheimer's, Parkinson's or affective disorders are increasing medical and social problems. Among the wide spectrum of potentially destructive events, oxidative stress and disrupted metabolism of some neurotransmitters such as acetylcholine, GABA, glutamate, serotonin or dopamine appear to play a decisive role. Biologically active plant polyphenols have been shown to exert a positive impact on the function of the central nervous system by modulation of metabolism and the action of some neurotransmitters.

METHODS

Based on published research, the pharmacological activities of some naturally occurring polyphenols have been reviewed, with a focus on their potential therapeutic importance in the regulation of neurotransmitter systems.

RESULTS

Phytochemicals can be classified into several groups and most of them possess anticancer, antioxidative, anti-inflammatory and neuroprotective properties. They can also modulate the metabolism or action of some neurotransmitters and/or their receptors. Based on these properties, phytochemicals have been used in traditional medicine for ages, although it was focused mainly on treating symptoms. However, growing evidence indicates that polyphenols may also prevent or slow neurological diseases.

CONCLUSION

Phytochemicals seem to be less toxic than synthetic drugs and they can be a safer alternative for currently used preparations, which exert adverse side effects. The neuroprotective actions of some plant polyphenols in the regulation of neurotransmitters metabolism, functioning of neurotransmitters receptors and antioxidative defense have potential therapeutic applications in various neurodegenerative disorders.

Effects of aqueous extract of Hyssopus officinalis on seizures induced by pentylenetetrazole and hippocampus mRNA level of iNOS in rats

OBJECTIVE

We examined the effectiveness of Hyssopus officinalis (hyssop) aqueous extract on pentylenetetrazole (PTZ)-induced acute seizures and the hippocampus iNOS (inducible nitric oxide synthases) gene expression as a potential mediator of the effects.

MATERIALS AND METHODS

Adult male Wistar rats were used. Tonic-clonic seizures were induced by intraperitoneal (i.p.) injection of PTZ (80 mg/kg) then behavioral profile during 30 min was characterized by stages defined as seizure scores. Hyssop extract were prepared and injected (i.p.) 15 minutes before the seizure induction at three doses 50, 100 and 200 mg/kg. Experimental groups were as below: (1) saline+PTZ (n=5); (2) Hyssop 50mg/kg+PTZ (n=10); (3) Hyssop 100mg/kg+PTZ (n=10); (4) Hyssop 200 mg/kg+PTZ (n=8). Two hours after the experimental procedure, all animals were decapitated, brain was removed and right hippocampus was quickly dissected. After total RNA extraction and cDNA synthesis quantitative PCR were used for gene expression of iNOS.

RESULTS

Our results showed significant increase (p<0.05) in latency to reach stages 5 and 6 of tonic-clonic seizure at dose 100 mg/kg hyssop extract. In addition, this dose caused significant increase in the gene expression of iNOS in the hippocampus.

CONCLUSION

It seems a 100 mg/kg dose of hyssop extract might have anticonvulsant effects. However, these anticonvulsant effects might not occur through the iNOS gene expression.

Sleep Promoting Effect of Luteolin in Mice via Adenosine A1 and A2A Receptors

Luteolin, a widespread flavonoid, has been known to have neuroprotective activity against various neurologic diseases such as epilepsy, and Alzheimer’s disease. However, little information is available regarding the hypnotic effect of luteolin. In this study, we evaluated the hypnotic effect of luteolin and its underlying mechanism. In pentobarbital-induced sleeping mice model, luteolin (1, and 3 mg/kg, p.o.) decreased sleep latency and increased the total sleep time. Through electroencephalogram (EEG) and electromyogram (EMG) recording, we demonstrated that luteolin increased non-rapid eye movement (NREM) sleep time and decreased wake time. To evaluate the underlying mechanism, we examined the effects of various pharmacological antagonists on the hypnotic effect of luteolin. The hypnotic effect of 3 mg/kg of luteolin was not affected by flumazenil, a GABAA receptor-benzodiazepine (GABAAR-BDZ) binding site antagonist, and bicuculine, a GABAAR-GABA binding site antagonist. On the other hand, the hypnotic effect of 3 mg/kg of luteolin was almost completely blocked by caffeine, an antagonist for both adenosine A1 and A2A receptor (A1R and A2AR), 8-Cyclopentyl-1,3-dipropylxanthine (DPCPX), an A1R antagonist, and SCH-58261, an A2AR antagonist. From the binding affinity assay, we have found that luteolin significantly binds to not only A1R but also A2AR with IC₅₀ of 1.19, 0.84 μg/kg, respectively. However, luteolin did not bind to either BDZ-receptor or GABAAR. From these results, it has been suggested that luteolin has hypnotic efficacy through A1R and A2AR binding.

Perspective: Therapeutic Potential of Flavonoids as Alternative Medicines in Epilepsy

Epilepsy is a chronic neurological disorder that affects many people worldwide. Temporal lobe epilepsy is the most common and most studied type of epilepsy, but the pathological mechanisms underlying this condition are poorly understood. More than 20 antiepileptic drugs (AEDs) have been developed and used for the treatment of epilepsy; however, 30% of patients still experience uncontrolled epilepsy and associated comorbidities, which impair their quality of life. In addition, various side effects have been reported for AEDs, such as drowsiness, unsteadiness, dizziness, blurred or double vision, tremor (shakiness), greater risk of infections, bruising, and bleeding. Thus, critical medical needs remain unmet for patients with uncontrolled epilepsy. Flavonoids belong to a subclass of polyphenols that are widely present in fruits, vegetables, and certain beverages. Recently, many studies have reported that some flavonoids elicit various beneficial effects in patients with epilepsy without causing the side effects associated with conventional medical therapies. Moreover, flavonoids may have a property of regulating microRNA expression associated with inflammation and cell survival. These findings suggest that flavonoids, which are more effective but impose fewer adverse effects than conventional AEDs, could be used in the treatment of epilepsy.

γ-Aminobutyric acid is closely associated with accumulation of flavonoids

γ-Aminobutyric acid (GABA) is an important neurotransmitter in mammals whose receptor is reported to be regulated by flavonoids. In plants, it is considered to be at the intersection of carbon and nitrogen metabolism, but its relationship with flavonoid metabolism remains unclear. Our recent RNA-seq analysis showed that expression of flavonoid biosynthetic genes was influenced in poplar by the blockage of α-ketoglutarate dehydrogenase (α-KGDH) activity and the application of GABA under NaCl stress, accompanied by the changes in GABA shunt activity. Here, we further found that the flavonoid accumulation was significantly affected by blocking the activities of α-KGDH and GABA transaminase as well as applying exogenous GABA, coupled with the changes of endogenous GABA contents. Key genes involved in the flavonoid biosynthetic pathway were also significantly influenced, including two PALs, 4CL, and two CHSs. Our results suggest that the GABA shunt is closely associated with the metabolism of flavonoids, which would benefit future understanding of GABA's roles in carbon allocation by regulating the pathway of flavonoid biosynthesis under normal or stress conditions.

Chalcone derivatives: synthesis, in vitro and in vivo evaluation of their anti-anxiety, anti-depression and analgesic effects

Anxiety disorders, depression and pain are highly prevalent pathologies. Their pharmacotherapy is associated with unwanted side effects; hence there is a clinical need to develop more effective drugs with fewer adverse reactions.

Chalcones are one of the major classes of naturally occurring compounds. Chalcones and their derivatives have a huge importance in medicinal chemistry, displaying a wide range of pharmacological activities including anti-inflammatory, antimicrobial, antioxidant, cytotoxic and antitumor actions.

The aim of this work was to evaluate chalcone effects on different targets involved in these pathologies. We have synthesized a series of simple chalcone derivatives taking common structural requirements described in literature related to their anxiolytic-like, antidepressant-like and/or antinociceptive properties into account.

Furthermore, their potential in vitro effects towards different targets involved in these pathologies were evaluated. We have obtained twenty chalcones with moderate to high yields and assessed their ability to bind distinctive receptors, from rat brain homogenates, by displacement of labelled specific ligands: [³H] FNZ (binding site of benzodiazepines/GABA_A), [³H] 8-OH-DPAT (serotonin 5-HT_1A) and [³H] DAMGO (μ-opioid). Those compounds that showed the better in vitro activities were evaluated in mice using different behavioural tasks. In vivo results showed that 5′-methyl-2′-hydroxychalcone (9) exerted anxiolytic-like effects in mice in the plus maze test. While chalcone nuclei (1) revealed antidepressant-like activities in the tail suspension test. In addition, the novel 5′-methyl-2′-hydroxy-3′-nitrochalcone (12) exhibited antinociceptive activity in acute chemical and thermal nociception tests (writhing and hot plate tests). In conclusion, chalcones are thus promising compounds for the development of novel drugs with central nervous system (CNS) actions.

Phytochemical Analysis and Central Effects of Annona Muricata Linnaeus: Possible Involvement of the Gabaergic and Monoaminergic Systems

Annona muricata Linnaeus (Annonaceae), popularly known as graviola, is used in folk medicine as both sedative and anticonvulsant. This study correlates the neurochemical profile with the behavioral effects of the hydroalcoholic extract from the leaves of Annona muricata (HLEAM) in mice, proposing to elucidate their mechanism of action on the central nervous system. Flavonoids and phenolic compounds were identified and quantified by High Performance Liquid Chromatography (HPLC) method. The acute toxicity (median lethal dose - LD50) was determined by probitos method using the percentage of mortality based on the Hippocratic screen. HLEAM (25, 50 and 100 mg/kg) was tested, intraperitoneally (i.p.), in models of sedation, anxiety, motor coordination, and seizures. The endogenous levels of dopamine, norepinephrine and DOPAC were assayed by reverse-phase HPLC with electrochemical detection. The HPLC analysis of the extract revealed the presence of flavonoids (quercetin, isoquercitrin, quercitrin, rutin, and kaempferol) and phenolics acids (gallic, chlorogenic, ellagic and caffeic acids). The LD50 was 1091.7 mg/kg and Hippocratic screening indicated central nervous system depressant effect. HLEAM presented sedative effects at doses of 25, 50, and 100 mg/kg, as well as anxiolytic and anticonvulsant effects at a dose of 100 mg/kg. In addition, these effects were partially reversed by flumazenil. The monoamines analysis by HPLC showed that HLEAM decreased the level of norepinefrine and dopamine in the mouse brain striatum. Thus, the results indicate a possible interaction of HLEAM with the GABAergic and monoaminergic systems, adding medicinal value to the popular use of the plant for the treatment of behavioral and neurological disorders.

Curcumol allosterically modulates GABA(A) receptors in a manner distinct from benzodiazepines

Inhibitory A type γ-aminobutyric acid receptors (GABA_ARs) play a pivotal role in orchestrating various brain functions and represent an important molecular target in neurological and psychiatric diseases, necessitating the need for the discovery and development of novel modulators. Here, we show that a natural compound curcumol, acts as an allosteric enhancer of GABA_ARs in a manner distinct from benzodiazepines. Curcumol markedly facilitated GABA-activated currents and shifted the GABA concentration-response curve to the left in cultured hippocampal neurons. When co-applied with the classical benzodiazepine diazepam, curcumol further potentiated GABA-induced currents. In contrast, in the presence of a saturating concentration of menthol, a positive modulator for GABA_AR, curcumol failed to further enhance GABA-induced currents, suggesting shared mechanisms underlying these two agents on GABA_ARs. Moreover, the benzodiazepine antagonist flumazenil did not alter the enhancement of GABA response by curcumol and menthol, but abolished that by DZP. Finally, mutations at the β2 or γ2 subunit predominantly eliminated modulation of recombinant GABA_ARs by curcumol and menthol, or diazepam, respectively. Curcumol may therefore exert its actions on GABA_ARs at sites distinct from benzodiazepine sites. These findings shed light on the future development of new therapeutics drugs targeting GABA_ARs.

Effects of Acute Blueberry Flavonoids on Mood in Children and Young Adults

Epidemiological evidence suggests that consumption of flavonoids (usually via fruits and vegetables) is associated with decreased risk of developing depression. One plausible explanation for this association is the well-documented beneficial effects of flavonoids on executive function (EF). Impaired EF is linked to cognitive processes (e.g., rumination) that maintain depression and low mood; therefore, improved EF may reduce depressionogenic cognitive processes and improve mood. Study 1: 21 young adults (18–21 years old) consumed a flavonoid-rich blueberry drink and a matched placebo in a counterbalanced cross-over design. Study 2: 50 children (7–10 years old) were randomly assigned to a flavonoid-rich blueberry drink or a matched placebo. In both studies, participants and researchers were blind to the experimental condition, and mood was assessed using the Positive and Negative Affect Schedule before and 2 h after consumption of the drinks. In both studies, the blueberry intervention increased positive affect (significant drink by session interaction) but had no effect on negative affect. This observed effect of flavonoids on positive affect in two independent samples is of potential practical value in improving public health. If the effect of flavonoids on positive affect is replicated, further investigation will be needed to identify the mechanisms that link flavonoid interventions with improved positive mood.

Inhibition of Human Monoamine Oxidase: Biological and Molecular Modeling Studies on Selected Natural Flavonoids

Naturally occurring flavonoids display a plethora of different biological activities, but emerging evidence suggests that this class of compounds may also act as antidepressant agents endowed with multiple mechanisms of action in the central nervous system, increasing central neurotransmission, limiting the reabsorption of bioamines by synaptosomes, and modulating the neuroendocrine and GABA_A systems. Due to their presence in foods, food-derived products, and nutraceuticals, we established their role and structure-activity relationships as reversible and competitive human monoamine oxidase (MAO) inhibitors. In addition, molecular modeling studies, which evaluated their modes of MAO inhibition, are presented. These findings could provide pivotal implications in the quest of novel drug-like compounds and for the establishment of harmful drug-dietary supplement interactions commonly reported in the therapy with antidepressant agents.

Russian olive (Elaeagnus angustifolia) as a herbal healer

Introduction:Elaeagnus spp. is one in the family of riparian trees growing near the rivers or water corridors. In this family, Elaeagnus angustifolia (Russian olive) is famous because of its medical applications.

Methods: A comprehensive review was performed to extract the related data from published literature.

Results: Traditionally, it has been used as an analgesic, antipyretic and diuretic herbal medicine. A large number of compounds have been derived from Russian olive and made this plant a source of flavonoids, alkaloids, minerals and vitamins. Although the purpose of most studies is to use this plant for preparation of herbal medicines and as an ingredient for drug formulation, there is no available drug dosage form commercially.

Conclusion: This review aimed to provide the most important documentary information on the active components of Elaeagnus spp. and their relation to the pharmacological properties and compare them with reported medicinal effects.

The Effect of a Combination Treatment Using Palonosetron, Promethazine, and Dexamethasone on the Prophylaxis of Postoperative Nausea and Vomiting and QTc Interval Duration in Patients Undergoing Craniotomy under General Anesthesia: A Pilot Study

Introduction

Postoperative nausea and vomiting (PONV) is a displeasing experience that distresses surgical patients during the first 24 h after a surgical procedure. The incidence of postoperative nausea occurs in about 50%, the incidence of postoperative vomiting is about 30%, and in high-risk patients, the PONV rate could be as high as 80%. Therefore, the study design of this single arm, non-randomized, pilot study assessed the efficacy and safety profile of a triple therapy combination with palonosetron, dexamethasone, and promethazine to prevent PONV in patients undergoing craniotomies under general anesthesia.

Methods

The research protocol was approved by the institutional review board and 40 subjects were provided written informed consent. At induction of anesthesia, a triple therapy of palonosetron 0.075 mg IV, dexamethasone 10 mg IV, and promethazine 25 mg IV was given as PONV prophylaxis. After surgery, subjects were transferred to the surgical intensive care unit or post anesthesia care unit as clinically indicated. Ondansetron 4 mg IV was administered as primary rescue medication to subjects with PONV symptoms. PONV was assessed and collected every 24 h for 5 days via direct interview and/or medical charts review.

Results

The overall incidence of PONV during the first 24 h after surgery was 30% (n = 12). The incidence of nausea and emesis 24 h after surgery was 30% (n = 12) and 7.5% (n = 3), respectively. The mean time to first emetic episode, first rescue, and first significant nausea was 31.3 (±33.6), 15.1 (±25.8), and 21.1 (±25.4) hours, respectively. The overall incidence of nausea and vomiting after 24–120 h period after surgery was 30% (n = 12). The percentage of subjects without emesis episodes over 24–120 h postoperatively was 70% (n = 28). No subjects presented a prolonged QTc interval ≥500 ms before and/or after surgery.

Conclusion

Our data demonstrated that this triple therapy regimen may be an adequate alternative regimen for the treatment of PONV in patients undergoing neurological surgery under general anesthesia. More studies with a control group should be performed to demonstrate the efficacy of this regimen and that palonosetron is a low risk for QTc prolongation.

ClinicalTrials.gov Identifier

NCT02635828 (https://clinicaltrials.gov/show/NCT02635828).

Hydroalcoholic extract of needles of Pinus eldarica enhances pentobarbital-induced sleep: possible involvement of GABAergic system

OBJECTIVE

Insomnia is accompanied by several health complications and the currently used soporific drugs can induce several side effects such as psychomotor impairment, amnesia, and tolerance. The present study was planned to investigate the sleep prolonging effect of Pinus eldarica.

MATERIALS AND METHODS

Hydroalcoholic extract (HAE) of P. eldarica, its water fraction (WF), ethyl acetate fraction (EAF) and n-butanol fraction (NBF) were injected (intraperitoneally) to mice 30 min before administration of pentobarbital. Then, the latent period and continuous sleeping time were recorded. Also, LD50 of P. eldarica extract was determined and the possible neurotoxicity of the extract was tested on neural PC12 cells.

RESULTS

The HAE and NBF decreased the latency of sleep (p<0.05) and significantly increased duration of sleep (p<0.05) induced by pentobarbital. These effects of P. eldarica were reversed by flumazenil. The LD50 value for HAE was found to be 4.8 g/Kg. HAE and its fractions did not show neurotoxic effects in cultured PC12-cell line.

CONCLUSION

The present data indicate that P. eldarica potentiated pentobarbital hypnosis without major toxic effect. Most probably, the main components responsible for this effect are non-polar agents which are found in NBF of this plant.

Polyphenols and the human brain: plant “secondary metabolite” ecologic roles and endogenous signaling functions drive benefits

Flavonoids and other polyphenols are ubiquitous plant chemicals that fulfill a range of ecologic roles for their home plant, including protection from a range of biotic and abiotic stressors and a pivotal role in the management of pathogenic and symbiotic soil bacteria and fungi. They form a natural part of the human diet, and evidence suggests that their consumption is associated with the beneficial modulation of a number of health-related variables, including those related to cardiovascular and brain function. Over recent years, the consensus as to the mechanisms responsible for these effects in humans has shifted away from polyphenols having direct antioxidant effects and toward their modulation of cellular signal transduction pathways. To date, little consideration has been given to the question of why, rather than how, these plant-derived chemicals might exert these effects. Therefore, this review summarizes the evidence suggesting that polyphenols beneficially affect human brain function and describes the current mechanistic hypotheses explaining these effects. It then goes on to describe the ecologic roles and potential endogenous signaling functions that these ubiquitous phytochemicals play within their home plant and discusses whether these functions drive their beneficial effects in humans via a process of “cross-kingdom” signaling predicated on the many conserved similarities in plant, microbial, and human cellular signal transduction pathways.

Flavones from Erythrina falcata are modulators of fear memory

Background

Flavonoids, which have been identified in a variety of plants, have been demonstrated to elicit beneficial effects on memory. Some studies have reported that flavonoids derived from Erythrina plants can provide such beneficial effects on memory. The aim of this study was to identify the flavonoids present in the stem bark crude extract of Erythrina falcata (CE) and to perform a bioactivity-guided study on conditioned fear memory.

Methods

The secondary metabolites of CE were identified by high performance liquid chromatography combined with a diode array detector, electrospray ionization tandem mass spectrometry (HPLC-DAD-ESI/MSⁿ) and nuclear magnetic resonance (NMR). The buthanolic fraction (BuF) was obtained by partitioning. Subfractions from BuF (BuF1 – BuF6) and fraction flavonoidic (FfA and FfB) were obtained by flash chromatography. The BuF3 and BuF4 fractions were used for the isolation of flavonoids, which was performed using HPLC-PAD. The isolated substances were quantified by HPLC-DAD and their structures were confirmed by nuclear magnetic resonance (NMR). The activities of CE and the subfractions were monitored using a one-trial, step-down inhibitory avoidance (IA) task to identify the effects of these substances on the acquisition and extinction of conditioned fear in rats.

Results

Six subclasses of flavonoids were identified for the first time in CE. According to our behavioral data, CE, BuF, BuF3 and BuF4, the flavonoidic fractions, vitexin, isovitexin and 6-C-glycoside-diosmetin improved the acquisition of fear memory. Rats treated with BuF, BuF3 and BuF4 were particularly resistant to extinction. Nevertheless, rats treated with FfA and FfB, vitexin, isovitexin and 6-C-glycoside-diosmetin exhibited gradual reduction in conditioned fear response during the extinction retest session, which was measured at 48 to 480 h after conditioning.

Conclusions

Our results demonstrate that vitexin, isovitexin and diosmetin-6-C-glucoside and flavonoidic fractions resulted in a significant retention of fear memory but did not prevent the extinction of fear memory. These results further substantiate that the treatment with pure flavonoids or flavanoid-rich fractions might represent potential therapeutic approaches for the treatment of neurocognitive disorders, improvement of memory acquisition and spontaneous recovery of fear.