Anti-depressant-like effect of vitexin in BALB/c mice and evidence for the involvement of monoaminergic mechanisms

New insights into anti-depression effects of bioactive phytochemicals

Depression is one of the most common psychological disorders, and due to its high prevalence and mortality rates, it imposes a significant disease burden. Contemporary treatments for depression involve various synthetic drugs, which have limitations such as side effects, single targets, and slow onset of action. Unlike synthetic medications, phytochemicals offer the benefits of a multi-target and multi-pathway mode of treatment for depression. In this literature review, we describe the pharmacological actions, experimental models, and clinical trials of the antidepressant effects of various phytochemicals. Additionally, we summarize the potential mechanisms by which these phytochemicals prevent depression, including regulating neurotransmitters and their receptors, the HPA axis, inflammatory responses, managing oxidative stress, neuroplasticity, and the gut microbiome. Phytochemicals exert therapeutic effects through multiple pathways and targets, making traditional Chinese medicine (TCM) a promising adjunctive antidepressant for the prevention, alleviation, and treatment of depression. Therefore, this review aims to provide robust evidence for subsequent research into developing phytochemical resources as effective antidepressant agents.

Chia (Salvia hispanica L.), a functional 'superfood': new insights into its botanical, genetic and nutraceutical characteristics

BACKGROUND

Chia (Salvia hispanica L.) seeds have become increasingly popular among health-conscious consumers owing to their high content of ω-3 fatty acids, which provide various health benefits. Comprehensive chemical analyses of the fatty acids and proteins in chia seeds have been conducted, revealing their functional properties. Recent studies have confirmed the high ω-3 content of chia seed oil and have hinted at additional functional characteristics.

SCOPE

This review article aims to provide an overview of the botanical, morphological and biochemical features of chia plants, seeds and seed mucilage. Additionally, we discuss the recent developments in genetic and molecular research on chia, including the latest transcriptomic and functional studies that examine the genes responsible for chia fatty acid biosynthesis. In recent years, research on chia seeds has shifted its focus from studying the physicochemical characteristics and chemical composition of seeds to understanding the metabolic pathways and molecular mechanisms that contribute to their nutritional benefits. This has led to a growing interest in various pharmaceutical, nutraceutical and agricultural applications of chia. In this context, we discuss the latest research on chia and the questions that remain unanswered, and we identify areas that require further exploration.

CONCLUSIONS

Nutraceutical compounds associated with significant health benefits, including ω-3 polyunsaturated fatty acids, proteins and phenolic compounds with antioxidant activity, have been measured in high quantities in chia seeds. However, comprehensive investigations through both in vitro experiments and in vivo animal and controlled human trials are expected to provide greater clarity on the medicinal, antimicrobial and antifungal effects of chia seeds. The recently published genome of chia and gene-editing technologies, such as CRISPR, facilitate functional studies deciphering molecular mechanisms of biosynthesis and metabolic pathways in this crop. This necessitates development of stable transformation protocols and creation of a publicly available lipid database, mutant collection and large-scale transcriptomic datasets for chia.

Vitexin Mitigates Haloperidol-Induced Orofacial Dyskinesia in Rats through Activation of the Nrf2 Pathway

Vitexin (VTX), a C-glycosylated flavone found in various medicinal herbs, is known for its antioxidant, anti-inflammatory, and neuroprotective properties. This study investigated the protective effects of VTX against orofacial dyskinesia (OD) in rats, induced by haloperidol (HPD), along with the neuroprotective mechanisms underlying these effects. OD was induced by administering HPD (1 mg/kg i.p.) to rats for 21 days, which led to an increase in the frequency of vacuous chewing movements (VCMs) and tongue protrusion (TP). VTX (10 and 30 mg/kg) was given intraperitoneally 60 min after each HPD injection during the same period. On the 21st day, following assessments of OD, the rats were sacrificed, and nitrosative and oxidative stress, antioxidant capacity, mitochondrial function, neuroinflammation, and apoptosis markers in the striatum were measured. HPD effectively induced OD, while VTX significantly reduced HPD-induced OD, decreased oxidative stress, enhanced antioxidant capacity, prevented mitochondrial dysfunction, and reduced neuroinflammatory and apoptotic markers in the striatum, and the protective effects of VTX on both behavioral and biochemical aspects of HPD-induced OD were significantly reduced when trigonelline (TGN), an inhibitor of the nuclear factor erythroid-2-related factor 2 (Nrf2)-mediated pathway, was administered. These findings suggest that VTX provides neuroprotection against HPD-induced OD, potentially through the Nrf2 pathway, indicating its potential as a therapeutic candidate for the prevention or treatment of tardive dyskinesia (TD) in clinical settings. However, further detailed research is required to confirm these preclinical findings and fully elucidate VTX's therapeutic potential in human studies.

Effectiveness of Tri-Kaysorn-Mas Extract in Ameliorating Cognitive-like Behavior Deficits in Ovariectomized Mice via Activation of Multiple Mechanisms

Postmenopausal women have a higher probability of experiencing cognitive alterations compared to men, suggesting that the decline in female hormones may contribute to cognitive deterioration. Thailand traditionally uses Tri-Kaysorn-Mas (TKM), a blend of three medicinal herbs, as a tonic to stimulate appetite and relieve dyspepsia. Due to its antioxidant and anti-acetylcholinesterase activities, we investigated the effects of TKM (50 and 100 mg/kg/day, p.o., for 8 weeks) on cognitive deficits and their underlying causes in an ovariectomized (OVX) mouse model of menopause. OVX mice showed cognitive impairment in the Y-maze, novel object recognition task (NORT), and Morris water maze (MWM) behavioral tests, along with atrophic changes to the uterus, altered levels of serum 17β-estradiol, and down-regulated expression of estrogen receptors (ERα and ERβ). These behavioral effects were reversed by TKM. TKM decreased malondialdehyde (MDA) levels and mitigated oxidative stress in the brain by enhancing the activity of superoxide dismutase (SOD) and catalase (CAT) and by up-regulating the antioxidant-related gene Nrf2 while down-regulating Keap1. TKM also counteracted OVX-induced neurodegeneration by enhancing the expression of the neurogenesis-related genes BDNF and CREB. The results indicate that TKM extract alleviates oxidative brain damage and neurodegeneration while enhancing cognitive behavior in OVX mice, significantly improving cognitive deficiencies related to menopause/ovariectomy through multiple targets.

Chemical Composition, Antioxidant Activities, Antidepressant Effect, and Lipid Peroxidation of Peruvian Blueberry: Molecular Docking Studies on Targets Involved in Oxidative Stress and Depression

Blueberries (Vaccinium corymbosum L.) are cultivated worldwide and are among the best dietary sources of bioactive compounds with beneficial health effects. This study aimed to investigate the components of Peruvian blueberry using high-performance liquid chromatography coupled to electrospray ionization and quadrupole time-of-flight mass spectrometry (HPLC-ESI-QTOF-MS/MS), identifying 11 compounds. Furthermore, we assessed in vitro the antioxidant activity and in vivo the antidepressant effect using a rat model and protective effect on lipid peroxidation (in the serum, brain, liver, and stomach). We also conducted molecular docking simulations with proteins involved in oxidative stress and depression for the identified compounds. Antioxidant activity was assessed by measuring total phenolic and flavonoid contents, as well as using 1,1-diphenyl-2-picrylhydrazin (DPPH), 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonic) acid (ABTS•+), and ferric-reducing antioxidant power (FRAP) assays. Peruvian blueberries demonstrated higher antioxidant activity than Vaccinium corymbosum fruits from Chile, Brazil, the United States, Turkey, Portugal, and China. The results showed that oral administration of Peruvian blueberries (10 and 20 mg/kg) for 28 days significantly (p < 0.001) increased swimming and reduced immobility in the forced swimming test (FST). Additionally, at doses of 40 and 80 mg/kg, oxidative stress was reduced in vivo (p < 0.001) by decreasing lipid peroxidation in brain, liver, stomach, and serum. Molecular docking and absorption, distribution, metabolism, excretion, and toxicity (ADMET) predictions were performed. In the molecular docking studies, quercitrin and 3,5-di-O-caffeoylquinic acid showed the best docking scores for nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, superoxide dismutase, and xanthine oxidase; while 3,5-dicaffeoylquinic acid methyl ester and caffeoyl coumaroylquinic acid had the best docking scores for monoamine oxidase and serotonin receptor 5-HT2. In summary, our results suggest that the antidepressant and protective effects against lipid peroxidation might be related to the antioxidant activity of Peruvian Vaccinium corymbosum L.

Multi-effective components and their target mechanism of Ziziphi Spinosae Semen in the treatment of insomnia

Insomnia is a common and refractory disease. Since more than 2000 years ago, people have been using Ziziphi Spinosae Semen (ZSS). However, there are lack of molecular mechanisms of sleep promotion effects of ZSS. The purpose of this study is to clarify the active ingredients in ZSS that are used to treat insomnia. Using a method called cellular label-free integrative pharmacology (CLIP), we established five insomnia-related target models, including serotonin (5HT2A and 5HT1A), melatonin (MT1), dopamine (D2) and epinephrine (β2) receptors. The one-dimensional (1D) fractions of ZSS extract were prepared on a RZC18 column and assayed on five models. Subsequently, the active fraction was further analyzed, fractionated and quantified using a two-dimensional (2D) liquid phase method coupled with a charged aerosol detector (CAD), This CAD-coupled 2D-LC method requires micro-fractions from the 1D separation and thus it greatly saves sample amounts and corresponding preparation time, and quickly conduct activity screening. The composition of the active 2D fractions was then determined using three-dimensional (3D) HPLC-MS, and molecular docking was separately carried out for the described compounds on the targets for activity prediction. Seven compounds were predicted to be active on 5HT2A, and two compounds on D2. We experimentally verified the prediction and found that vitexin exhibited D2 agonistic activity, and nuciferine exhibited 5HT2A antagonistic activity. This study revealed the effective components and their targets of ZSS in the treatment of insomnia, also highlighted the potential of the CLIP technique and bioactivity guided multi-dimensional HPLC-MS in molecular mechanism elucidation for traditional Chinese medicines.

Immune sensing of food allergens promotes avoidance behaviour

In addition to its canonical function of protection from pathogens, the immune system can also alter behaviour1,2. The scope and mechanisms of behavioural modifications by the immune system are not yet well understood. Here, using mouse models of food allergy, we show that allergic sensitization drives antigen-specific avoidance behaviour. Allergen ingestion activates brain areas involved in the response to aversive stimuli, including the nucleus of tractus solitarius, parabrachial nucleus and central amygdala. Allergen avoidance requires immunoglobulin E (IgE) antibodies and mast cells but precedes the development of gut allergic inflammation. The ability of allergen-specific IgE and mast cells to promote avoidance requires cysteinyl leukotrienes and growth and differentiation factor 15. Finally, a comparison of C57BL/6 and BALB/c mouse strains revealed a strong effect of the genetic background on the avoidance behaviour. These findings thus point to antigen-specific behavioural modifications that probably evolved to promote niche selection to avoid unfavourable environments.

Beneficial Role of Vitexin in Parkinson's Disease

Today, Parkinson's disease (PD) is the foremost neurological disorder all across the globe. In the quest for a novel therapeutic agent for PD with a multimodal mechanism of action and relatively better safety profile, natural flavonoids are now receiving greater attention as a potential source of neuroprotection. Vitexin have been shown to exhibit diverse biological benefits in various disease conditions, including PD. It exerts its anti-oxidative property in PD patients by either directly scavenging reactive oxygen species (ROS) or by upregulating the expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and enhancing the activities of antioxidant enzymes. Also, vitexin activates the ERK1/1 and phosphatidyl inositol-3 kinase/Akt (PI3K/Akt) pro-survival signalling pathway, which upregulates the release of anti-apoptotic proteins and downregulates the expression of pro-apoptotic proteins. It could be antagonistic to protein misfolding and aggregation. Studies have shown that it can also act as an inhibitor of monoamine oxidase B (MAO-B) enzyme, thereby increasing striatal dopamine levels, and hence, restoring the behavioural deficit in experimental PD models. Such promising pharmacological potential of vitexin could be a game-changer in devising novel therapeutic strategies against PD. This review discusses the chemistry, properties, sources, bioavailability and safety profile of vitexin. The possible molecular mechanisms underlying the neuroprotective action of vitexin in the pathogenesis of PD alongside its therapeutic potential is also discussed.

The Protective Effect of Vitexin Compound B-1 on Rat Cerebral I/R Injury through a Mechanism Involving Modulation of miR-92b/NOX4 Pathway

BACKGROUND

Recent studies have uncovered that vitexin compound B-1 (VB-1) can protect neurons against hypoxia/reoxygenation (H/R)-induced oxidative injury through suppressing NOX4 expression.

OBJECTIVE

The aims of this study are to investigate whether VB-1 can protect the rat brain against ischemia/ reperfusion (I/R) injury and whether its effect on NOX4 expression is related to modulation of certain miRNAs expression.

METHODS

Rats were subjected to 2 h of cerebral ischemia followed by 24 h of reperfusion to establish an I/R injury model, which showed an increase in neurological deficit score and infarct volume concomitant with an upregulation of NOX4 expression, increase in NOX activity, and downregulation of miR-92b.

RESULTS

Administration of VB-1 reduced I/R cerebral injury accompanied by a reverse in NOX4 and miR-92b expression. Similar results were achieved in a neuron H/R injury model. Next, we evaluated the association of miR-92b with NOX4 by its mimics in the H/R model. H/R treatment increased neurons apoptosis concomitant with an upregulation of NOX4 and NOX activity while downregulation of miR-92b. All these effects were reversed in the presence of miR-92b mimics, confirming the function of miR-92b in suppressing NOX4 expression.

CONCLUSION

We conclude the protective effect of VB-1 against rat cerebral I/R injury through a mechanism involving modulation of miR-92b/NOX4 pathway.

Participation of the Serotonergic System and Brain-Derived Neurotrophic Factor in the Antidepressant-like Effect of Flavonoids

Depressive disorders are among the most disabling diseases experienced around the world, and their incidence has significantly increased over the last few decades due to multiple environmental, social, and biological factors. The search for new pharmacological alternatives to treat depression is a global priority. In preclinical research, molecules obtained from plants, such as flavonoids, have shown promising antidepressant-like properties through several mechanisms of action that have not been fully elucidated, including crossing of the blood brain barrier (BBB). This review will focus on discussing the main findings related to the participation of the serotonergic system and brain-derived neurotrophic factor (BDNF) on the antidepressant-like effect of some flavonoids reported by behavioral, neurochemical, and molecular studies. In this sense, evidence shows that depressive individuals have low levels of serotonin and BDNF, while flavonoids can reverse it. Finally, the elucidation of the mechanism used by flavonoids to modulate serotonin and BDNF will contribute to our understanding of the neurobiological bases underlying the antidepressant-like effects produced by these natural compounds.

Antidepressant and Cardioprotective Effects of Self-Nanoemulsifying Self-Nanosuspension Loaded with Hypericum perforatum on Post-Myocardial Infarction Depression in Rats

Hypericum perforatum (HP) is characterized by potent medicinal activity. However, the poor water solubility of many HP constituents limits their therapeutic effectiveness. Self-nanoemulsifying self-nanosuspension loaded with HP (HP.SNESNS) was formulated to improve the bioefficacy of HP. It was prepared using 10% triacetin, 57% Tween 20, and 33% PEG 400 and then incorporated with HP extract (100 mg/mL). HP.SNESNS demonstrated a bimodal size distribution (258.65 ± 29.35 and 9.08 ± 0.01 nm) corresponding to nanosuspension and nanoemulsion, respectively, a zeta potential of -8.03 mV, and an enhanced dissolution profile. Compared to the unformulated HP (100 mg/kg), HP.SNESNS significantly improved cardiac functions by decreasing the serum myocardial enzymes, nitric oxide (NO), and tumor necrosis factor- α (TNF-α) as well as restoring the heart tissue's normal architecture. Furthermore, it ameliorates anxiety, depressive-like behavior, and cognitive dysfunction by decreasing brain TNF-α, elevating neurotransmitters (norepinephrine and serotonin), and brain-derived neurotrophic factor (BDNF). In addition, HP.SNESNS augmented the immunohistochemical expression of cortical and hippocampal glial fibrillary acidic protein (GFAP) levels while downregulating the cortical Bcl-2-associated X protein (Bax) expression levels. Surprisingly, these protective activities were comparable to the HP (300 mg/kg). In conclusion, HP.SNESNS (100 mg/kg) exerted antidepressant and cardioprotective activities in the post-MI depression rat model.

Antidepressant-like effect of tofisopam in mice: A behavioural, molecular docking and MD simulation study

BACKGROUND

Depression is a disease that affects millions of people worldwide, and the discovery and development of effective and safe antidepressant drugs is one of the important topics of psychopharmacology.

OBJECTIVES

In this study, it was aimed to investigate the antidepressant-like activity potential of tofisopam, an anxiolytic drug with 2,3-benzodiazepine structure, and to elucidate the pharmacological mechanisms mediating this effect.

METHODS

The antidepressant-like activity of tofisopam was investigated using tail suspension and modified forced swimming tests. Possible interactions of tofisopam with µ- and δ-opioid receptor subtypes were clarified by pharmacological antagonism, molecular docking and molecular dynamics simulation studies.

RESULTS

Tofisopam (50 and 100 mg/kg) significantly shortened the immobility time of mice in both the tail suspension and the modified forced swimming tests. The drug, at the same doses, prolonged the duration of swimming and climbing behaviours measured in modified forced swimming tests. A dosage of 25 mg/kg was ineffective. Mechanistic studies showed that the pretreatment with p-chlorophenylalanine methyl ester (serotonin synthesis inhibitor; 4 consecutive days, 100 mg/kg), α-methyl-para-tyrosine methyl ester (catecholamine synthesis inhibitor; 100 mg/kg), naloxonazine (selective µ-opioid receptor blocker, 7 mg/kg) and naltrindole (a selective δ-opioid receptor blocker, 0.99 mg/kg) abolished the anti-immobility effect induced by the 50 mg/kg dose of tofisopam in the tail suspension tests. Our in silico studies supported the behavioural findings that the antidepressant-like effect of tofisopam is mediated by μ- and δ-opioid receptors.

CONCLUSION

This study is the first to show that tofisopam has antidepressant-like activity mediated by the serotonergic, catecholaminergic and opioidergic systems.

Antidepressant Activity of Curcuma heyneana

BACKGROUND: The resistance to depression therapy remains high, and therapy failure leads to suicide. Curcuma heyneana (C. heyneana) is a plant of Zingiberaceae. Conventionally, the rhizome has been used as an anxiolytic and sedative. However, the activity as antidepression has never been conducted. AIM: Therefore, this research was aimed to investigate the antidepressant activity of C. heyneana rhizome. METHODS: This research was conducted using male mice aged 2–3 months. Chronic mild stress for 14 days was used to induce depression, followed by administration of the extract at 50, 100, and 200 mg/kg for 10 days. Evaluation of antidepression was carried out using tail suspension test (TST), forced swim test (FST), open field test (OFT), and blood glucose and injury of gastric. Sertraline at the dose of 6.5 mg/kg was used as a positive control. RESULTS: The result revealed that stress induction for 14 days causes decreasing in locomotor activity and increased immobility. The extract administration at the doses of 100 and 200 mg/kg showed increased locomotor activity, which can be seen from the elevation of the central square and cross in the OFT (p < 0.05). The extract also decreased immobility in the tail suspension and FSTs (p < 0.05). Furthermore, the extract also prevents increases in blood glucose and gastric irritation. CONCLUSION: Extract of C. heyneana rhizome at the doses of 100 and 200 mg/kg has antidepressant activity by increasing locomotor activity, decreasing immobility time, and preventing elevation of blood glucose and gastric injury.

The Genus Alternanthera: Phytochemical and Ethnopharmacological Perspectives

Ethnopharmacological relevance: The genus Alternanthera (Amaranthaceae) comprises 139 species including 14 species used traditionally for the treatment of various ailments such as hypertension, pain, inflammation, diabetes, cancer, microbial and mental disorders.

Aim of the review: To search research gaps through critical assessment of pharmacological activities not performed to validate traditional claims of various species of Alternanthera. This review will aid natural product researchers in identifying Alternanthera species with therapeutic potential for future investigation.

Materials and methods: Scattered raw data on ethnopharmacological, morphological, phytochemical, pharmacological, toxicological, and clinical studies of various species of the genus Alternanthera have been compiled utilizing search engines like SciFinder, Google Scholar, PubMed, Science Direct, and Open J-Gate for 100 years up to April 2021.

Results: Few species of Alternanthera genus have been exhaustively investigated phytochemically, and about 129 chemical constituents related to different classes such as flavonoids, steroids, saponins, alkaloids, triterpenoids, glycosides, and phenolic compounds have been isolated from 9 species. Anticancer, antioxidant, antibacterial, CNS depressive, antidiabetic, analgesic, anti-inflammatory, and immunomodulator effects have been explored in the twelve species of the genus. A toxicity study has been conducted on 3 species and a clinical study on 2 species.

Conclusions: The available literature on pharmacological studies of Alternanthera species reveals that few species have been selected based on ethnobotanical surveys for scientific validation of their traditional claims. But most of these studies have been conducted on uncharacterized and non-standardized crude extracts. A roadmap of research needs to be developed for the isolation of new bioactive compounds from Alternanthera species, which can emerge out as clinically potential medicines.

Suppression of Adipogenesis and Fat Accumulation by Vitexin Through Activation of Hedgehog Signaling in 3T3-L1 Adipocytes

Many studies have demonstrated that adipogenesis is associated with obesity, and the Hedgehog (Hh) signaling pathway regulates adipogenesis and obesity. Following the screening study of the chemical library evaluating the effect of vitexin on Gli1 transcriptional activity, vitexin was chosen as a candidate for antiadipogenic efficacy. Vitexin significantly reduced lipid accumulation and suppressed C/EBPα (CCAAT/enhancer-binding protein α) and PPARγ (peroxisome proliferator-activated receptor γ) expression, which are known as key adipogenic factors in the early stages of adipogenesis by activating Hh signaling. Furthermore, Hh inhibitor GANT61 reversed the effect of AMP-activated protein kinase (AMPK) activator AICAR (5-aminoimidazole-4-carboxamide ribonucleotide), indicating that Hh signaling is an upstream regulator of AMPK in 3T3-L1 cells. Vitexin suppressed adipogenesis by regulating Hh signaling and phosphorylation of AMPK, leading to the inhibition of fat formation. These results suggest that vitexin can be considered a potent dietary agent in alleviating lipid accumulation and obesity.

Therapeutic and prophylactic effect of flavonoids in post-COVID-19 therapy

The high incidence of post-covid symptoms in humans confirms the need for effective treatment. Due to long-term complications across several disciplines, special treatment programs emerge for affected patients, emphasizing multidisciplinary care. For these reasons, we decided to look at current knowledge about possible long-term complications of COVID-19 disease and then present the effect of flavonoids, which could help alleviate or eliminate complications in humans after overcoming the COVID-19 infection. Based on articles published from 2003 to 2021, we summarize the flavonoids-based molecular mechanisms associated with the post-COVID-19 syndrome and simultaneously provide a complex view regarding their prophylactic and therapeutic potential. Review clearly sorts out the outcome of post-COVID-19 syndrome according particular body systems. The conclusion is that flavonoids play an important role in prevention of many diseases. We suggest that flavonoids as critical nutritional supplements, are suitable for the alleviation and shortening of the period associated with the post-COVID-19 syndrome. The most promising flavonoid with noteworthy therapeutic and prophylactic effect appears to be quercetin.

The role of serotonergic and catecholaminergic systems for possible antidepressant activity of apigenin

Background and objective

Although, the anti-depressant like effects of apigenin (APG) are documented in the literature, the underlying mechanism for exerting such an effect is still not clear. In this research, an attempt was made to determine the possible role of APG for antidepressant activity through serotonergic and catecholaminergic systems using standardized animal models.

Materials and methods

The antidepressant property of APG was determine by involving tail suspension (TST) and modified forced swimming tests (MFST). The effect of APG was evaluated at 25 and 50 mg/kg. In mechanistic models, animals were pretreated with catecholaminergic and serotonergic antagonists prior to administration of APG. The results obtained were statistically analyzed to determine the level of significance.

Results

The period of immobility in both models (TST and MFST) was significantly reduced by APG (25 and 50 mg/kg). The best therapetuic dose of APG (50 mg/kg) was selected for the mechanistic study. The anti-immobility effect of APG declined to a significant extent upon pretreatment with catecholaminergic antagonists (α-methyl-para-tyrosine methyl ester; SCH 23390; sulpiride; phentolamine) and serotonergic inhibitors (p-clorophenylalanine-methyl-ester; ondansetron) in both TST and MFST models. The antidepressant benefits of apigenin were only modestly reversed when rats were given propranolol.

Conclusions

The findings suggest that APG's antidepressant effect is mediated by the α-adrenergic, dopaminergic and 5-HT3 serotonergic receptors.

Emerging Role of Flavonoids as the Treatment of Depression

Depression is one of the most frequently observed psychological disorders, affecting thoughts, feelings, behavior and a sense of well-being in person. As per the WHO, it is projected to be the primitive cause of various other diseases by 2030. Clinically, depression is treated by various types of synthetic medicines that have several limitations such as side-effects, slow-onset action, poor remission and response rates due to complicated pathophysiology involved with depression. Further, clinically, patients cannot be given the treatment unless it affects adversely the job or family. In addition, synthetic drugs are usually single targeted drugs. Unlike synthetic medicaments, there are many plants that have flavonoids and producing action on multiple molecular targets and exhibit anti-depressant action by affecting multiple neuronal transmissions or pathways such as noradrenergic, serotonergic, GABAnergic and dopaminergic; inhibition of monoamine oxidase and tropomyosin receptor kinase B; simultaneous increase in nerve growth and brain-derived neurotrophic factors. Such herbal drugs with flavonoids are likely to be useful in patients with sub-clinical depression. This review is an attempt to analyze pre-clinical studies, structural activity relationship and characteristics of reported isolated flavonoids, which may be considered for clinical trials for the development of therapeutically useful antidepressant.

Brazilian passion fruit as a new healthy food: from its composition to health properties and mechanisms of action

The Brazilian biodiversity is one of the largest in the world, with about 41 000 species cataloged within two global biodiversity hotspots: Atlantic Forest and Cerrado, the Brazilian savannah. Passiflora, known also as passion flowers, is a genus of which 96% of its species are distributed in the Americas, mainly Brazil and Colombia. Passion fruit extracts have a commercial value on a global scale through the pharmaceutical, nutraceutical, self-care, and food and beverage industries. Passiflora are widely studied due to their potential antioxidant, anti-inflammatory, anxiolytic, antidepressant and vascular and neuronal protective effects, probably owing to their content of polyphenols. Passiflora setacea DC is a species of wild passion fruit from the Brazilian Cerrado, rich in flavonoid C-glycosides, homoorientin, vitexin, isovitexin and orientin. Intake of these plant food bioactives has been associated with protection against chronic non-communicable diseases (CNDCs), including cardiovascular diseases, cancers, and neurodegenerative diseases. In this review, we aimed to discuss the varieties of Passiflora, their content in plant food bioactives and their potential molecular mechanisms of action in preventing or reversing CNDCs.

Arbuscular mycorrhizal fungi, a key symbiosis in the development of quality traits in crop production, alone or combined with plant growth-promoting bacteria

Modern agriculture is currently undergoing rapid changes in the face of the continuing growth of world population and many ensuing environmental challenges. Crop quality is becoming as important as crop yield and can be characterised by several parameters. For fruits and vegetables, quality descriptors can concern production cycle (e.g. conventional or organic farming), organoleptic qualities (e.g. sweet taste, sugar content, acidity) and nutritional qualities (e.g. mineral content, vitamins). For other crops, however, the presence of secondary metabolites such as anthocyanins or certain terpenes in the targeted tissues is of interest as well, especially for their human health properties. All plants are constantly interacting with microorganisms. These microorganisms include arbuscular mycorrhizal fungi as well as certain soil bacteria that provide ecosystem services related to plant growth, nutrition and quality parameters. This review is an update of current research on the single and combined (co-inoculation) use of arbuscular mycorrhizal fungi and plant growth-promoting rhizobacteria in crop production, with a focus on their positive impacts on crop quality traits (e.g. nutritional value, organoleptic properties). We also highlight the need to dissect mechanisms regulating plant-symbionts and symbiont-symbiont interactions, to develop farming practices and to study a broad range of interactions to optimize the symbiotic potential of root-associated microorganisms.

An overview on therapeutic and medicinal potential of poly-hydroxy flavone viz. Heptamethoxyflavone, Kaempferitrin, Vitexin and Amentoflavone for management of Alzheimer's and Parkinson's diseases: a critical analysis on mechanistic insight

Neurodegenerative disorders occur when nerve cells in the brain or peripheral nervous system partial or complete fail in their functions and sometimes even die due to some injuries or aging. Neurodegenerative disorders such as Alzheimer's Disease (AD) and Parkinson's Disease (PD), have been majorly resulted due to degeneration of neurons and neuroinflammation progressively. There are many similarities that correlates both AD and PD on a cellular and sub-cellular level. Therefore, a hope for therapeutic advancement for simultaneous upgradation in both the diseases are directly depending on the discovery of common mechanism at molecular and cellular level. Recent and past evidences from scientific literature supporting the efficacy of plants flavonoids in treatment and protection of both AD and PD. Further, dietary flavones, specially Heptamethoxyflavone, Kaempferitrin, Vitexin and Amentoflavone gains recently much more attention for producing many health beneficiary effects including neuroprotection. Despite of these evidence a detailed updated overview of neuroprotective effects against both AD and PD by Heptamethoxyflavone, Kaempferitrin, Vitexin and Amentoflavone are still missing. In this context several published studies were assessed by using various online electronic search engines/databases to meet the objective from 1981 to 2021 (Approx. 224). Therefore, present review was designed to deliver the detailed description on these flavones including therapeutic benefits in AD, PD and other CNS complications with critical analysis on underlying mechanisms.

Distribution, Metabolism, Excretion and Toxicokinetics of Vitexin in Rats and Dogs

Background:

Vitexin is the main bioactive compound of hawthorn (Crataegus pinnatifida), a famous traditional Chinese medicine, and vitexin for injection is currently in phase I clinical trial in China.

Objective:

This investigation systematically evaluated the metabolism and toxicokinetics of vitexin in rats and dogs.

Methods:

Rats and beagle dogs were administrated different doses of vitexin, and then the plasma concentration, tissue distribution, excretion, metabolism, pharmacokinetics and plasma protein binding were investigated.

Results :

The elimination half-life (t1/2) values in rats after a single intravenous dose of 3, 15 and 75 mg/kg were estimated as 43.53±10.82, 22.86±4.23, and 21.17±8.64 min, and the values of the area under the plasma concentration-time curve (AUC0→∞) were 329.34±144.07, 974.79±177.27, and 5251.49±786.98 mg•min/L, respectively. The plasma protein binding rate in rats was determined as about 65% by equilibrium dialysis after 72 hr. After 24 hr of intravenous administration, 16.30%, 3.47% and 9.72% of the given dose were excreted in urine, feces and bile, respectively. The metabolites of the vitexin were hydrolyzed via deglycosylation. The pharmacokinetics of dogs after intravenous administration revealed t1/2, AUC0-∞ and mean residence time (MRT0-∞) values of 20.43±6.37 min, 227.96±26.68 mg•min/L and 17.12±4.33 min, respectively. The no-observed-adverse- effect level (NOAEL) was 50 mg/kg body weight/day. There was no significant accumulation effect at 8 or 20 mg/kg/day in dogs over 92 days of repeated administration. For the 50 mg/kg/- day dose group, the exposure (AUC, Cmax) decreased significantly with prolonged administration. This trend suggests that repeated administration accelerates vitexin metabolism.

Conclusion:

The absorption of vitexin following routine oral administration was very low. To improve the bioavailability of vitexin, the development of an injectable formulation would be a suitable alternative choice.

A Combined Network Pharmacology and Molecular Docking Approach to Investigate Candidate Active Components and Multitarget Mechanisms of Hemerocallis Flowers on Antidepressant Effect

Objective

The purpose of our research is to systematically explore the multiple mechanisms of Hemerocallis fulva Flowers (HF) on depressive disorder (DD).

Methods

The components of HF were searched from the literature. The targets of components were obtained from PharmMapper. After that, Cytoscape software was used to build a component-target network. The targets of DD were collected from DisGeNET, PharmGKB, TTD, and OMIM. Protein-protein interactions (PPIs) among the DD targets were executed to screen the key targets. Afterward, the GO and KEGG pathway enrichment analysis were performed by the KOBAS database. A compound-target-KEGG pathway network was built to analyze the key compounds and targets. Finally, the potential active substances and targets were validated by molecular docking.

Results

A total of 55 active compounds in HF, 646 compound-related targets, and 527 DD-related targets were identified from public databases. After treated with PPI, 219 key targets of DD were acquired. The gene enrichment analysis suggested that HF probably benefits DD patients by modulating pathways related to the nervous system, endocrine system, amino acid metabolism, and signal transduction. The network analysis showed the critical components and targets of HF on DD. Results of molecular docking increased the reliability of this study.

Conclusions

It predicted and verified the pharmacological and molecular mechanism of HF against DD from a holistic perspective, which will also lay a foundation for further experimental research and rational clinical application of DD.

Natural Compounds as Medical Strategies in the Prevention and Treatment of Psychiatric Disorders Seen in Neurological Diseases

Psychiatric disorders are frequently encountered in many neurological disorders, such as Alzheimer’s and Parkinson diseases along with epilepsy, migraine, essential tremors, and stroke. The most common comorbid diagnoses in neurological diseases are depression and anxiety disorders along with cognitive impairment. Whether the underlying reason is due to common neurochemical mechanisms or loss of previous functioning level, comorbidities are often overlooked. Various treatment options are available, such as pharmacological treatments, cognitive-behavioral therapy, somatic interventions, or electroconvulsive therapy. However oral antidepressant therapy may have some disadvantages, such as interaction with other medications, low tolerability due to side effects, and low efficiency. Natural compounds of plant origin are extensively researched to find a better and safer alternative treatment. Experimental studies have shown that phytochemicals such as alkaloids, terpenes, flavonoids, phenolic acids as well as lipids have significant potential in in vitro and in vivo models of psychiatric disorders. In this review, various efficacy of natural products in in vitro and in vivo studies on neuroprotective and their roles in psychiatric disorders are examined and their neuro-therapeutic potentials are shed light.

Flavor Characteristics of Ganpu Tea Formed During the Sun-Drying Processing and Its Antidepressant-Like Effects

Ganpu tea is a novel type of tea beverage with unique and pleasant flavor that encases Pu-erh tea leaves within an intact mandarin peel. However, to date, no holistic and detail studies on its chemical composition and biological activities have been reported yet. In the present study, by applying UPLC-Q-TOF and UPLC-MS technology, we systematically identified and analyzed 104 water-soluble compounds of Ganpu tea and their variation trend during the sun-drying processing. The results showed that the generation of pigments and gallic acid coincided with a dramatic decrease in catechin content, and a significant increase in alkaloid and flavonoid contents. The conversion of these compounds can contribute to the improvement of sensory attributes of Ganpu tea and maybe indispensable to its unique flavor. Moreover, the mice given orally with high dose of Ganpu tea (0.4 g/kg) showed a significantly reduced immobility duration as compared to that of the negative control group (p < 0.01) both in the forced swimming test and tail suspension test. Together, these results indicate that the sun-drying processing was indispensable to the formation of the unique flavor for Ganpu tea. Multiple types of compounds of Ganpu tea may collectively provide the synergistic attributes to its antidepressant-like properties.

A Review of Plant Extracts and Plant-Derived Natural Compounds in the Prevention/Treatment of Neonatal Hypoxic-Ischemic Brain Injury

Neonatal hypoxic-ischemic (HI) brain injury is one of the major drawbacks of mortality and causes significant short/long-term neurological dysfunction in newborn infants worldwide. To date, due to multifunctional complex mechanisms of brain injury, there is no well-established effective strategy to completely provide neuroprotection. Although therapeutic hypothermia is the proven treatment for hypoxic-ischemic encephalopathy (HIE), it does not completely chang outcomes in severe forms of HIE. Therefore, there is a critical need for reviewing the effective therapeutic strategies to explore the protective agents and methods. In recent years, it is widely believed that there are neuroprotective possibilities of natural compounds extracted from plants against HIE. These natural agents with the anti-inflammatory, anti-oxidative, anti-apoptotic, and neurofunctional regulatory properties exhibit preventive or therapeutic effects against experimental neonatal HI brain damage. In this study, it was aimed to review the literature in scientific databases that investigate the neuroprotective effects of plant extracts/plant-derived compounds in experimental animal models of neonatal HI brain damage and their possible underlying molecular mechanisms of action.

Inclusion of vitexin in β-cyclodextrin: preparation, characterization and expectorant/antitussive activities

The study aimed to include the isolated vitexin of Jatropha mutabilis in the β-cyclodextrin cavity to improve the solubility of this flavone. Its characterization was performed by techniques such as ¹H NMR/ROESY (Nuclear Magnetic Resonance Spectroscopy), FT-IR (Infrared Spectroscopy with Fourier Transform), SEM (Morphological analysis of IC by Scanning Electron Microscopy) and dissolution study in vitro. In addition, the following activities were evaluated in the animal models: expectorant, phenol red dosage in bronchoalveolar lavage and antitussive, cough induced by citric acid. In the characterization of the complex, interaction between hydrogens of ring B of vitexin and (H3) of β-CD was observed, in addition to changes in morphology. In the dissolution test, an increase in the rate of dissolution of vitexin was observed in the first 30 min for the CI vitexin/β-CD when compared with vitexin. Regarding the pharmacological activity, it was observed that the inclusion complex (IC) vitexin/β-CD in the equivalent doses of 0.2, 1 and 5 mg/kg of flavone presented higher expectorant activity when compared to vitexin (p < 0.05), suggesting increased bioavailability. As for the antitussive activity, both vitexin and the complex had similar effects and were dose independent. In the toxicity test using Artemia salina, vitexin and IC vitexin/β-CD were considered non-toxic. At last, the study efficacy of vitexin/β-CD IC as an expectorant and of vitexin as antitussive. All of these data are being described for the first time.

Vitexin Possesses Anticonvulsant and Anxiolytic-Like Effects in Murine Animal Models

Different types of epilepsy and forms of pathological anxiety have been described as significant neurological disorders that may exist as comorbidities. Some of those disorders share the association of affected limbic areas/neuropathological triggers as well as the use of drugs for their clinical management. The aim of this work was to investigate the anticonvulsant and anxiolytic properties of the vitexin (apigenin-8-C-glucoside), since this compound is a flavonoid usually found as one of the major constituents in several medicinal plants claimed as anxiolytics and/or anticonvulsants. This investigation was performed by the use of a series of classical murine animal models of chemically induced-seizures and of anxiety-related tests (open-field, elevated plus-maze, and light-dark box tests). Here, we show that the systemic administration of vitexin (1.25; 2.5 and 5 mg/kg; i.p.) exhibited selective protection against chemically-induced seizures. Vitexin did not block seizures evoked by glutamate receptors agonists (NMDA and kainic acid), and it did not interfere with the latencies for these seizures. Conversely, the same treatments protected the animals in a dose-dependent manner against the seizures evoked by the Gabaergic antagonists picrotoxin and PTZ and rise the latency time for the first seizure on non-protected animals. The higher dose of vitexin protected 100% of animals against the tonic-clonic seizures triggered by GABA antagonists. The results from open-field, elevated plus-maze, and light-dark box tests indicated the anxiolytic properties of vitexin at similar range of doses described for the anticonvulsant action screening. Furthermore, these results pointed that vitexin did not cause sedation or locomotor impairment on animals. The selective action of vitexin against picrotoxin and PTZ may reinforce the hypothesis by which this compound acts mainly by the modulation of GABAergic neurotransmission and/or related pathways. This could be useful to explain the dual activity of vitexin as anticonvulsant and anxiolytic, and highlight the pharmacological interest on this promising flavonoid.

Review of the effects of vitexin in oxidative stress-related diseases

Vitexin is an apigenin flavone glycoside found in food and medicinal plants. It has a variety of pharmacological effects, including antioxidant, anti-inflammatory, anticancer, antinociceptive, and neuroprotective effects. This review study summarizes all the protective effects of vitexin as an antioxidant against reactive oxygen species, lipid peroxidation, and other oxidative damages in a variety of oxidative stress-related diseases, including seizure, memory impairment, cerebral ischemia, neurotoxicity, myocardial and respiratory injury, and metabolic dysfunction, with possible molecular and cellular mechanisms. This review describes any activation or inhibition of the signaling pathways that depend on the antioxidant activity of vitexin. More basic research is needed on the antioxidative effects of vitexin in vivo, and carrying out clinical trials for the treatment of oxidative stress-related diseases is also recommended.

In Vivo Antidepressant Effect of Passiflora edulis f. flavicarpa into Cationic Nanoparticles: Improving Bioactivity and Safety

A variety of neuroactive flavonoids can be found in the species of the Passiflora genus; however, their difficulty in crossing the blood-brain barrier limits their in vivo neuropharmacological activity. In this study, cationic nanoparticles were developed as a novel nanocarrier for improving the antidepressant activity of Passiflora edulis f. flavicarpa leaf extract. Formulations obtained using Eudragit E PO polymethylmethacrylate copolymer, as polymeric matrix had their physicochemical properties investigated. The analytical content of the flavonoids vicenin-2, orientin, isoorientin, vitexin, and isovitexin was determined in the plant extract. Small-sized and spherical nanoparticles loaded with Passiflora edulis f. flavicarpa were obtained with positive zeta potential and high encapsulation efficiency. In addition, the nanosystems were shown to be stable for at least 6 months. The antidepressant activity of P. edulis extract (50 and 100 mg/kg) as well as the extract-loaded nanoparticles (5 mg/kg) were investigated in mice using the forced swimming test, where the latter increased the potency of the former by 10-fold. In addition, histopathological and biochemical analysis confirmed the biocompatibility of the extract-loaded nanoparticles. This study demonstrated that the Eudragit cationic nanoparticles were able to improve the antidepressant activity of P. edulis in the central nervous system of mice.

Use of mycorrhizal fungi releases the application of organic fertilizers to increase the production of leaf vitexin in yellow passion fruit

BACKGROUND

Low-cost organic fertilizers, such as coconut powder and vermicompost, and arbuscular mycorrhizal fungi (AMF) may benefit the Passiflora edulis f. flavicarpa plant. However, it has not been established whether the joint application of these inputs may increase the production of vitexin and other molecules associated with the phytotherapeutic properties of this plant. Here, we tested the hypothesis that the application of AMF and organic fertilizers maximizes the production of bioactive compounds in leaves of P. edulis.

RESULTS

The inoculation of Acaulospora longula into P. edulis grown in fertilization-free soil promoted an increase of 86% in the concentration of leaf vitexin, 10.29% in the concentration of total phenols, and 13.78% in the concentration of total tannins in relation to the AMF-free control, rendering soil fertilization superfluous.

CONCLUSION

The application of A. longula increases the production of foliar biomolecules, such as vitexin, in yellow passion fruit plants. Thus, the addition of coconut powder and vermicompost to the substrate composition is not necessary, leading to the commercialized production of phytomass in the herbal medicines industry. © 2019 Society of Chemical Industry.

Phytochemical Profile and Antidepressant Effect of Ormosia henryi Prain Leaf Ethanol Extract

The Ormosia henryi Prain leaf (OHPL) is a new bioactive resource with potential antidepressant activity, but few reports have confirmed its chemical composition or antidepressant effect. To investigate the phytochemical profile of OHPL ethanol extract (OHPLE), six flavone C-glycosides and two flavone O-glycosides were purified by high-speed counter-current chromatography combined with preparative high-performance liquid chromatography (HSCCC-prep-HPLC). The eight isolated compounds were identified by NMR and MS. Forty-six flavonoids, including flavones, flavone C-glycosides, flavone O-glycosides, isoflavones, isoflavone O-glycosides, prenylflavones and polymethoxyflavones were definitively or tentatively identified from OHPLE using ultra-performance liquid chromatography/ electrospray ionization quadrupole time-of-flight mass spectrometry (UPLC-ESI-QTOF-MS/MS) on the basis of fragment ions that are characteristic of these isolated compounds. The results of the antidepressant assay suggest that OHPLE significantly improved depression-related behaviors of chronic unpredictable mild stress (CUMS) mice. The observed changes in these mice after OHPLE treatment were an increased sucrose preference index, reduced feeding latency, prolonged tail suspension time, and upregulated expression of brain-derived neurotrophic factor (BDNF). The details of the phytochemicals and the antidepressant effect of OHPLE are reported here for the first time. This study indicates that the OHPL, enriched in flavone C-glycosides, is a new resource that might be potentially applied in the field of nutraceuticals (or functional additives) with depression-regulating functions.

Quinoa Secondary Metabolites and Their Biological Activities or Functions

Quinoa (Chenopodium quinoa Willd.) was known as the "golden grain" by the native Andean people in South America, and has been a source of valuable food over thousands of years. It can produce a variety of secondary metabolites with broad spectra of bioactivities. At least 193 secondary metabolites from quinoa have been identified in the past 40 years. They mainly include phenolic acids, flavonoids, terpenoids, steroids, and nitrogen-containing compounds. These metabolites exhibit many physiological functions, such as insecticidal, molluscicidal and antimicrobial activities, as well as various kinds of biological activities such as antioxidant, cytotoxic, anti-diabetic and anti-inflammatory properties. This review focuses on our knowledge of the structures, biological activities and functions of quinoa secondary metabolites. Biosynthesis, development and utilization of the secondary metabolites especially from quinoa bran were prospected.

A newly isolated human intestinal bacterium strain capable of deglycosylating flavone C-glycosides and its functional properties

Background

Flavone C-glycosides are difficult to be deglycosylated using traditional chemical methods due to their solid carbon–carbon bond between sugar moieties and aglycones; however, some bacteria may easily cleave this bond because they generate various specific enzymes.

Results

A bacterial strain, named W12-1, capable of deglycosylating orientin, vitexin, and isovitexin to their aglycones, was isolated from human intestinal bacteria in this study and identified as Enterococcus faecalis based on morphological examination, physiological and biochemical identification, and 16S rDNA sequencing. The strain was shown to preferentially deglycosylate the flavone C-glycosides on condition that the culture medium was short of carbon nutrition sources such as glucose and starch, and its deglycosylation efficiency was negatively correlated with the content of the latter two substances.

Conclusion

This study provided a new bacterial resource for the cleavage of C-glycosidic bond of flavone C-glycosides and reported the carbon nutrition sources reduction induced deglycosylation for the first time.

Electronic supplementary material

The online version of this article (10.1186/s12934-019-1144-7) contains supplementary material, which is available to authorized users.

Production of biomolecules of interest to the anxiolytic herbal medicine industry in yellow passionfruit leaves (Passiflora edulis f. flavicarpa) promoted by mycorrhizal inoculation

BACKGROUND

Our contemporary way of life has led us to consume high amounts of chemically-synthesized allopathic medicinal products and anxiolytics to which a viable alternative is the use of Passiflora-based herbal medicines with composition containing vitexin, a flavonoid with anxiolytic and antidepressant properties. Arbuscular mycorrhizal fungi (AMF) are known for enhancing the production of biomolecules, however, increase production of phytochemistry in Passiflora edulis f. flavicarpa has not been reported in the literature. Our aim was to select AMF to benefit the production of vitexin in leaves of P. edulis by inoculating seedlings in the region of roots with Acaulospora longula, Claroideoglomus etunicatum and Gigaspora albida.

RESULTS

The inoculation increased the concentration of vitexin in 63.64% and the inoculation with A. longula also increased the content of flavonoids and total saponins in the leaves in relation to the control.

CONCLUSION

The increase in the production of vitexin in the leaf in response to the inoculation with AMF, with emphasis to A. longula, interests the pharmaceutical industry and can generate profit to the production of yellow passionfruit-based anxiolytic herbal medicine. © 2019 Society of Chemical Industry.

Synthesis of Novel Benzazole Derivatives and Evaluation of Their Antidepressant-Like Activities with Possible Underlying Mechanisms

Novel benzazole derivative compounds 4a–4h were obtained by the reaction of corresponding 2-(benzazol-2-ylthio)acetohydrazide and appropriate 4-substituted benzaldehydes. The chemical structures of the synthesized compounds were elucidated by FT-IR, ¹H-NMR, ¹³C-NMR and LCMS spectroscopic methods. Antidepressant-like effects of the compounds were evaluated by tail suspension test (TST) and modified forced swimming tests (MFST). Moreover, locomotor activities of the animals were assessed by an activity cage apparatus. In the series, compounds 4a, 4b, 4e and 4f (at 50 mg/kg) significantly decreased the immobility time of mice in both of the TST and MFST. The same compounds prolonged the swimming time of animals in MFST without any change in the climbing duration. These data indicated that compounds 4a, 4b, 4e and 4f possess significant antidepressant-like activities. Moreover, pre-treatments with p-chloro-phenylalanine methyl ester (an inhibitor of serotonin synthesis), NAN-190 (a 5-HT_1A antagonist), ketanserin (a 5-HT_2A/2C antagonist), and ondansetron (a 5-HT₃ antagonist) reversed the exhibited pharmacological effects. Results of the mechanistic studies suggested the involvement of serotonergic system and contributions of 5-HT_1A, 5-HT_2A/2C and 5-HT₃ receptors to the antidepressant-like effects of compounds 4a, 4b, 4e and 4f. Furthermore, unchanged locomotor activity of mice following the administrations of these four derivatives confirmed that the presented antidepressant-like effects are specific.

Synthesis of Some Novel Thiadiazole Derivative Compounds and Screening Their Antidepressant-Like Activities

Novel thiadiazole derivatives were synthesized through the reaction of acetylated 2-aminothiadiazole and piperazine derivatives. The chemical structures of the compounds were clarified by Infrared Spectroscopy (IR), ¹H Nuclear Magnetic Resonance Spectroscopy (¹H-NMR), ¹³C Nuclear Magnetic Resonance Spectroscopy (¹³C-NMR) and Electronspray Ionisation Mass Spectroscopy (ESI-MS) spectroscopic methods. Antidepressant-like activities were evaluated by the tail-suspension (TST) and modified forced swimming (MFST) methods. Besides, possible influence of the test compounds on motor activities of the animals were examined by activity cage tests. In the TST, administration of the compounds 2c, 2d, 2e, 2f, 2g and 2h significantly decreased the immobility time of mice regarding the control values. Further, in the MFST, the same compounds reduced the total number of immobility behaviors while increasing swimming performance. However, no change was observed in the total number of climbing behaviors. These data suggested that compounds 2c, 2d, 2e, 2f, 2g and 2h possess notable antidepressant-like activities. Reference drug fluoxetine (10 mg/kg) was also exhibited its antidepressant activity, as expected. No significant difference was seen between the locomotor activity values of the test groups signifying that observed antidepressant-like activities are specific. Theoretical calculation of absorption, distribution, metabolism, excretion (ADME) properties for the obtained compounds were performed and obtained data supported the antidepressant-like potential of these novel thiadiazole derivatives.

Camellia euphlebia exerts its antidepressant-like effect via modulation of the hypothalamic-pituitary-adrenal axis and brain monoaminergic systems

Camellia euphlebia (family, Theaceae) is a Chinese folk medicine, known for its multiple pharmacological properties. The present study aimed to provide further insights into the therapeutic basis of C. euphlebia using several animal behavioral tests and physiological indexes. Tail suspension test, forced swimming test, open-field test, chronic unpredictable mild stress (CUMS), reversal of reserpine-induced hypothermia and palpebral ptosis, and 5-hydroxytryptophane-induced head-twitch response were used to evaluate the antidepressant effect of aqueous extract of Camellia euphlebia (AEC) on mice. The possible underlying mechanism was explored by investigating the changes associated with several parameters of animal behavior, as well as the changes in monoamine neurotransmitter and stress hormone levels in these animals during the tests. Mice administered AEC at 100 and 200 mg/kg/day doses for 7 days showed significantly reduced immobility duration in forced swimming test and tail suspension test, whilst exhibiting no apparent changes in locomotor activity. Additionally, administration of AEC also effectively antagonized reserpine-induced palpebral ptosis and hypothermia and enhanced 5-hydroxytryptophane-induced head-twitch response. AEC significantly elevated the levels of serotonin, noradrenaline and dopamine in the blood and brain compared to non-treated mice. After 28 days of administration, the maximum AEC dose (100 mg/kg/day) significantly reversed CUMS-induced inhibition of weight gain and sucrose intake, while decreasing the levels of plasma adrenocorticotropic hormone and serum corticosterone. The antidepressant effect of AEC appeared to involve the alteration of hypothalamic-pituitary-adrenal axis and monoaminergic systems.

Advances in the Preclinical Study of Some Flavonoids as Potential Antidepressant Agents

Flavonoids are phenolic compounds found commonly in plants that protect them against the negative effects of environmental insults. These secondary metabolites have been widely studied in preclinical research because of their biological effects, particularly as antioxidant agents. Diverse flavonoids have been studied to explore their potential therapeutic effects in the treatment of disorders of the central nervous system, including anxiety and depression. The present review discusses advances in the study of some flavonoids as potential antidepressant agents. We describe their behavioral, physiological, and neurochemical effects and the apparent mechanism of action of their preclinical antidepressant-like effects. Natural flavonoids produce antidepressant-like effects in validated behavioral models of depression. The mechanism of action of these effects includes the activation of serotonergic, dopaminergic, noradrenergic, and γ-aminobutyric acid-ergic neurotransmitter systems and an increase in the production of neural factors, including brain-derived neurotrophic factor and nerve growth factor. Additionally, alterations in the function of tropomyosin receptor kinase B and activity of the enzyme monoamine oxidase A have been reported. In conclusion, preclinical research supports the potential antidepressant effects of some natural flavonoids, which opens new possibilities of evaluating these substances to develop complementary therapeutic alternatives that could ameliorate symptoms of depressive disorders in humans.

Antidepressant Flavonoids and Their Relationship with Oxidative Stress

Depression is a serious disorder that affects hundreds of millions of people around the world and causes poor quality of life, problem behaviors, and limitations in activities of daily living. Therefore, the search for new therapeutic options is of high interest and growth. Research on the relationship between depression and oxidative stress has shown important biochemical aspects in the development of this disease. Flavonoids are a class of natural products that exhibit several pharmacological properties, including antidepressant-like activity, and affects various physiological and biochemical functions in the body. Studies show the clinical potential of antioxidant flavonoids in treating depressive disorders and strongly suggest that these natural products are interesting prototype compounds in the study of new antidepressant drugs. So, this review will summarize the chemical and pharmacological perspectives related to the discovery of flavonoids with antidepressant activity. The mechanisms of action of these compounds are also discussed, including their actions on oxidative stress relating to depression.

Antidepressant-like effect of gallic acid in mice: Dual involvement of serotonergic and catecholaminergic systems

AIMS

This study was planned to examine the antidepressant potency of gallic acid (30 and 60mg/kg), a phenolic acid widely distributed in nature, together with its possible underlying monoaminergic mechanisms.

MAIN METHODS

Antidepressant-like activity was assessed using the tail suspension (TST) and the modified forced swimming tests (MFST). Locomotor activity was evaluated in an activity cage.

KEY FINDINGS

Administration of gallic acid at 60mg/kg reduced the immobility duration of mice in both the TST and MFST without any changes in the locomotor activity. The anti-immobility effect observed in the TST was abolished with pre-treatment of p-chlorophenylalanine methyl ester (an inhibitor of serotonin synthesis; 100mg/kg i.p. administered for 4-consecutive days), ketanserin (a 5-HT2A/2C antagonist; 1mg/kg i.p.), ondansetron (a 5-HT3 antagonist; 0.3mg/kg i.p.), α-methyl-para-tyrosine methyl ester (an inhibitor of catecholamine synthesis; 100mg/kg i.p.), phentolamine (non-selective alpha-adrenoceptor antagonist; 5mg/kg i.p.), SCH 23390 (a dopamine D1 antagonist; 0.05mg/kg s.c.), and sulpiride (a dopamine D2/D3 antagonist; 50mg/kg i.p.). However, NAN 190 (a 5-HT1A antagonist; 0.5mg/kg i.p.) and propranolol (a non-selective β-adrenoceptor antagonist; 5mg/kg i.p.) pre-treatments were ineffective at reversing the antidepressant-like effects of gallic acid.

SIGNIFICANCE

The results of the present study indicate that gallic acid seems to have a dual mechanism of action by increasing not only serotonin but also catecholamine levels in synaptic clefts of the central nervous system. Further alpha adrenergic, 5-HT2A/2C and 5-HT3 serotonergic, and D1, D2, and D3 dopaminergic receptors also seem to be involved in this antidepressant-like activity.