6-Methoxyflavone antagonizes chronic constriction injury and diabetes associated neuropathic nociception expression.

Neuropathy is a disturbance of function or a pathological change in nerves causing poor health and quality of life. A proportion of chronic pain patients in the community suffer persistent neuropathic pain symptoms because current drug therapies may be suboptimal so there is a need for new therapeutic modalities. This study investigated the neuroprotective flavonoid, 6-methoxyflavone (6MF), as a potential therapeutic agent and gabapentin as the standard comparator, against neuropathic models. Thus, neuropathic-like states were induced in Sprague-Dawley rats using sciatic nerve chronic constriction injury (CCI) mononeuropathy and systemic administration of streptozotocin (STZ) to induce polyneuropathy. Subsequent behaviors reflecting allodynia, hyperalgesia, and vulvodynia were assessed and any possible motoric side-effects were evaluated including locomotor activity, as well as rotarod discoordination and gait disruption. 6MF (25-75 mg/kg) antagonized neuropathic-like nociceptive behaviors including static- (pressure) and dynamic- (light brushing) hindpaw allodynia plus heat/cold and pressure hyperalgesia in the CCI and STZ models. 6MF also reduced static and dynamic components of vulvodynia in the STZ induced polyneuropathy model. Additionally, 6MF reversed CCI and STZ suppression of locomotor activity and rotarod discoordination, suggesting a beneficial activity on motor side effects, in contrast to gabapentin. Hence, 6MF possesses anti-neuropathic-like activity not only against different nociceptive modalities but also impairment of motoric side effects.

5,7-Dimethoxycoumarin ameliorates vincristine induced neuropathic pain: potential role of 5HT3 receptors and monoamines.

Vincristine is the drug of choice for Hodgkin's lymphoma, acute lymphoblastic leukemia, and non-Hodgkin lymphoma. Despite its significant anticancer effects, it causes dose-dependent neuropathy, leading to compulsive dose reduction. The available drugs used for vincristine-induced neuropathic pain (VINP) have a range of safety, efficacy, and tolerability issues prompting a search for new therapies. 5,7-Dimethoxycoumarin (5,7-DMC) also known as citropten, is a natural coumarin found in the essential oils of citrus plants such as lime, lemons, and bergamots, and it possesses both antidepressant and anti-inflammatory effects. This study was designed to investigate the possible analgesic and antiallodynic effects of 5,7-DMC in a murine model of VINP. Vincristine was administered to groups of BALB/c male mice (0.1 mg/kg intraperitoneally) once daily for 14 days to induce VINP. Thermal hyperalgesia and mechanical allodynia were quantified using the tail immersion test and von Frey filament application method. The levels of monoamine neurotransmitters and vitamin C in frontal cortical, striatal and hippocampal tissues, as well as the TNF-α level in plasma, were quantified using high performance liquid chromatography and ELISA respectively. On day 15 of the protocol, acute treatment with 5,7-DMC clearly reversed VINP thermal hyperalgesia, mechanical static allodynia, mechanical dynamic allodynia, and cold allodynia. The activity of 5,7-DMC against hyperalgesia and allodynia was inhibited by pretreatment with ondansetron but not naloxone, implicating a 5-HT3 receptor involvement. VINP vitamin C levels were restored by 5,7-DMC in the frontal cortex, and changes in serotonin, dopamine, adenosine, inosine and hypoxanthine levels caused by vincristine were reversed either fully or partially. Additionally, the vincristine-induced rise in hippocampal serotonin, dopamine, inosine and striatal serotonin was appreciably reversed by 5,7-DMC. 5,7-DMC also reversed the vincristine-induced increase in the plasma level of TNF-α. In negating the changes in the levels of some neurotransmitters in the brain caused by vincristine, 5,7-DMC showed stronger effects than gabapentin. It was concluded that, there is a potential role of 5-HT3 receptors and monoamines in the amelioration of VINP induced by 5,7-DMC, and the use of this compound warrants further investigation.

Diosgenin normalization of disrupted behavioral and central neurochemical activity after single prolonged stress.

Introduction: Post-traumatic stress disorder (PTSD) is a chronic mental illness triggered by traumatic experiences such as wars, natural disasters, or catastrophes, and it is characterized by anxiety, depression and cognitive impairment. Diosgenin is a steroidal sapogenin with known neuroprotective and antioxidant properties. This study aimed to assess the pharmacological potential of diosgenin in a single prolonged stress (SPS) model of PTSD, plus other behavioral models along with any consequent alterations in brain neurochemistry in male mice. Methodology: SPS was induced by restraining animals for 2 h, followed by 20 min of forced swim, recuperation for 15 min, and finally, exposure to ether to induce anesthesia. The SPS-exposed animals were treated with diosgenin (20, 40, and 60 mg/kg) and compared with the positive controls, fluoxetine or donepezil, then they were observed for any changes in anxiety/depression-like behaviors, and cognitive impairment. After behavioral screening, postmortem serotonin, noradrenaline, dopamine, vitamin C, adenosine and its metabolites inosine and hypoxanthine were quantified in the frontal cortex, hippocampus, and striatum by high-performance liquid chromatography. Additionally, animal serum was screened for changes in corticosterone levels. Results: The results showed that diosgenin reversed anxiety- and depression-like behaviors, and ameliorated cognitive impairment in a dose-dependent manner. Additionally, diosgenin restored monoamine and vitamin C levels dose-dependently and modulated adenosine and its metabolites in the brain regions. Diosgenin also reinstated otherwise increased serum corticosterone levels in SPS mice. Conclusion: The findings suggest that diosgenin may be a potential candidate for improving symptoms of PTSD.

Effect of Gabapentin-Fluoxetine Derivative GBP1F in a Murine Model of Depression, Anxiety and Cognition.

Background and Objective: Gabapentin is a commonly prescribed antiepileptic agent for seizures, which is also used for pain and addiction management. Due to growing evidence of its abuse liability, there has been an incentive to synthesise potentially useful gabapentin derivatives devoid of adverse effects. A gabapentin adduct with a fluoxetine moiety, GBP1F, was assessed for any sedative, cognitive, anxiolytic, or antidepressant-like actions in murine behavioral models. Materials and Methods: Selected groups of mice were used for each behavioral paradigm, and the effect of GBP1F (5, 10, and 15 mg/kg) was assessed using spontaneous locomotor activity, the tail suspension test, elevated plus maze test, and the Y maze test models. Immediately following behavioral experiments, postmortem striatal and hippocampal tissues were evaluated for the effect of GBP1F on concentrations of dopamine, DOPAC, HVA, serotonin, 5-HIAA, vitamin C, and noradrenaline using high performance liquid chromatography with electrochemical detection. Results: GBP1F induced a mild suppression of locomotor activity, ameliorated anxiety and depression-like behavior, did not alter cognitive behavior, and raised serotonin and 5-HIAA concentrations in the hippocampus and striatum. GBP1F also positively enhanced dopamine and vitamin C tissue levels in the striatum. Thus, GBP1F represents a compound with anxiolytic- and antidepressant-like effects though further studies are warranted at the molecular level to focus on the precise mechanism(s) of action.

Effects of 1-methyl-1, 2, 3, 4-tetrahydroisoquinoline on a diabetic neuropathic pain model.

Background: Neuropathy is a prevalent and debilitating complication of poorly managed diabetes, contributing towards poor quality of life, amputation risk, and increased mortality. The available therapies for diabetic neuropathic pain (DPN) have limitations in terms of efficacy, tolerability and patient compliance. Dysfunction in the peripheral and central monoaminergic system has been evidenced in various types of neuropathic and acute pain. The objective of the present study was to investigate 1-methyl 1, 2, 3, 4-tetrahydroisoquinoline (1MeTIQ), an endogenous amine found in human brain with a known neuroprotective profile, in a model of streptozotocin (STZ) induced neuropathic pain. Methods: Diabetic neuropathy in male BALB/c mice was induced by intraperitoneal injection of a single dose of STZ (200 mg/kg). Upon development of DPN after 4 weeks, mice were investigated for mechanical allodynia (von Frey filament pressure test) and thermal hyperalgesia (tail immersion test). Ondansetron (1.0 mg/kg i.p.), naloxone (3.0 mg/kg i.p.) and yohimbine (2.0 mg/kg i.p.) were used to elucidate the possible mechanism involved. Postmortem frontal cortical, striatal and hippocampal tissues were dissected and evaluated for changes in levels of dopamine, noradrenaline and serotonin using High-Performance Liquid Chromatography (HPLC) with UV detection. Results: Acute administration of 1MeTIQ (15-45 mg/kg i.p.) reversed streptozotocin-induced diabetic neuropathic static mechanical allodynia (von Frey filament pressure test) and thermal hyperalgesia (tail immersion test), these outcomes being comparable to standard gabapentin. Furthermore, HPLC analysis revealed that STZ-diabetic mice expressed lower concentrations of serotonin in all three brain regions examined, while dopamine was diminished in the striatum and 1MeTIQ reversed all these neurotransmitter modifications. These findings suggest that the antihyperalgesic/antiallodynic activity of 1MeTIQ may be mediated in part via supraspinal opioidergic and monoaminergic modulation since they were naloxone, yohimbine and ondansetron reversible. Conclusion: It was also concluded that acute treatment with 1MeTIQ ameliorated STZ-induced mechanical allodynia and thermal hyperalgesia and restored brain regionally altered serotonin and dopamine concentrations which signify a potential for 1MeTIQ in the management of DPN.

Fraxetin attenuates disrupted behavioral and central neurochemical activity in a model of chronic unpredictable stress.

Purpose: Chronic unpredictable stress (CUS) induces long-term neuronal and synaptic plasticity with a neurohormonal disbalance leading to the development of co-existing anxiety, depression, and cognitive decline. The side effects and delayed onset of current clinically used antidepressants has prompted a quest for antidepressants with minimum drawbacks. Fraxetin is a natural coumarin derivative with documented antioxidant and neuroprotective activity though its effects on stress are unknown. This study therefore aimed to investigate any possible acute effect of fraxetin in behavioral tests including a CUS paradigm in correlation with brain regional neurochemical changes. Methods: Mice were subjected to a series of mild stressors for 14 days to induce CUS. Furthermore, behavioral performance in the open field test, forced swim test (FST), Y-maze and elevated plus-maze were evaluated. Postmortem frontal cortical, hippocampal and striatal tissues were analyzed via high-performance liquid chromatography (HPLC) for neurochemical changes. Result: Acute administration of fraxetin (20-60 mg/kg, orally) decreased depression-like behavior in the FST and behavioral anxiety in both the open field test and elevated plus-maze. Memory deficits induced during the CUS paradigm were markedly improved as reflected by enhanced Y maze performance. Concurrent biochemical and neurochemical analyses revealed that only the two higher fraxetin doses decreased elevated serum corticosterone levels while diminished serotonin levels in the frontal cortex, striatum and hippocampus were reversed, though noradrenaline was only raised in the striatum. Concomitantly, dopamine levels were restored by fraxetin at the highest dose exclusively in the frontal cortex. Conclusion: Acute treatment with fraxetin attenuated CUS-induced behavioral deficits, ameliorated the increased corticosterone level and restored altered regional neurotransmitter levels and this may indicate a potential application of fraxetin in the management of anxiety and depression modeled by CUS. However, further studies are warranted regarding the chronic effects of fraxetin behaviorally and neurochemically.

The Neuroprotective Propensity of Organic Extracts of Acacia stenophylla Bark and Their Effectiveness Against Scopolamine-/Diazepam-Induced Amnesia in Mice.

Background: Alzheimer's disease (AD) is a neurodegenerative disorder that is more prevalent in the elderly. There is extensive literature on using Acacia species against central nervous system disorders, although Acacia stenophylla has not been investigated for any neuroprotective potential. The purpose of the study was to elucidate the ameliorative effect of ethyl acetate (ASEE) and butanol (ASB) extracts from the bark of A. stenophylla on memory deficits and cognitive dysfunction in scopolamine- or diazepam-induced amnesia in mice. Methods: The phytochemical constituents of the extracts of A. stenophylla were determined by GC-MS and the in vitro anticholinesterase plus antioxidant activities were also evaluated. Anti-amnesic effects were determined employing the open field test, elevated plus maze (EPM), Morris water maze (MWM), and Y-maze paradigms. Results: The in vitro cholinesterase assays disclosed a concentration-dependent inhibition of both AChE and BuChE with IC50 values of 28.48 and 44.86 µg/mL for the ASEE extract and 32.04 and 50.26 µg/mL for the ASB extract against AChE and BuChE respectively. DPPH and H2O2 antioxidant assays revealed respective IC50 values for the ASEE extract of 28.04 and 59.84 µg/mL, plus 32.77 and 64.65 µg/mL for ASB extract. The findings revealed that both extracts possessed substantial antioxidant properties. Furthermore, these fractions restored scopolamine- and diazepam-induced memory deficits in a dose-dependent manner, as observed by a significant decrease in the transfer latency in EPM, reduction in escape latency, added time spent in the target quadrant in the MWM, and elevated spontaneous alternation behavior (SAB) in the Y-maze test. Conclusion: The ameliorative effect of A. stenophylla on scopolamine- and diazepam-induced amnesia can be attributed to antioxidant and anticholinesterase activity. Consequently, the use of A. stenophylla might be exploited in the alleviation of oxidative stress and the management of AD.

An Update on Promising Agents against COVID-19: Secondary Metabolites and Mechanistic Aspects.

BACKGROUND: Coronavirus disease 2019 (COVID­19) is caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) and is associated with a high level of mortality. OBJECTIVE: This updated review aims to present the most important traditional medicinal plants and some of their secondary metabolites that have previously and more recently been shown to affect viruses and may represent a beneficial contributory step against SARS-CoV-2 as the cause of COVID-19. Moreover, the mechanism aspects of these secondary metabolites were discussed, which may help find more reliable drugs against SARSCoV- 2. METHODS: Articles were searched on scientific websites including Google Scholar, Scopus, Web of Science, PubMed, and IranMedex using the search terms herbal medicine and traditional medicine with coronavirus, SARS-CoV-2, or COVID-19. Human, animal, and in vitro studies were identified in the search. RESULTS: Medicinal plants and their secondary metabolites may possess a potential role in combating this disease, and researchers suggest that some of these plants and their constituent compounds have inhibitory activity on coronaviruses. Numerous medicinal plants, their extracts, and secondary metabolites have been investigated over a period of time for antiviral activity. Among them, kaempferol, silybin, myricitrin, licoleafol, and curcumin are promising agents with potential activity against SARS-CoV-2. Natural compounds can form strong bonds with the active sites of SARS-CoV-2 protease. Structural and non-structural SARS-CoV-2 proteins such as Spike protein, PLpro, and 3CLpro are inhibited by these phytochemicals. CONCLUSION: Prospective treatments targeted at the life cycle stages of the virus may eventuate from research endeavors, and it must not be discounted that therapy originally derived from plant secondary metabolite sources may potentially have a part to play.

Pharmacological evaluation of the gabapentin salicylaldehyde derivative, gabapentsal, against tonic and phasic pain models, inflammation, and pyrexia.

Gabapentinoids are effective drugs in most animal models of pain and inflammation with variable effects in humans. The current study evaluated the pharmacological activity of gabapentin (GBP) and its salicylaldehyde derivative (gabapentsal; [2-(1-(((2-hydroxybenzylidene) amino) methyl) cyclohexyl) acetic acid]; GPS) in well-established mouse models of nociceptive pain, inflammatory edema, and pyrexia at doses of 25-100 mg/kg. GPS allayed tonic visceral pain as reflected by acetic acid-induced nociception and it also diminished thermally induced nociception as a mimic of phasic thermal pain. Antagonism of GPS-induced antinociceptive activities by naloxone (NLX, 1.0 mg/kg, subcutaneously, s.c), beta-funaltrexamine (ß-FNT, 5.0 mg/kg, s.c), naltrindole (NT, 1.0 mg/kg, s.c), and nor-binaltorphimine (NOR-BNI, 5.0 mg/kg, s.c), and pentylenetetrazole (PTZ-15 mg/kg, intraperitoneally, i.p) implicated an involvement of both opioidergic and GABAergic mechanisms. Tail immersion test was conducted in order to delineate the mechanistic insights of antinociceptive response. Inflammatory edema induced by carrageenan, histamine, or serotonin was also effectively reversed by GPS in a fashion analogous to aspirin (150 mg/kg, i.p), chlorpheniramine (1.0 mg/kg, i.p), and mianserin (1.0 mg/kg, i.p), respectively. Additionally, yeast-induced pyrexia was decreased by GPS in a comparable manner to acetaminophen (50 mg/kg, i.p). These observations suggest that GPS possesses ameliorative properties in tonic, phasic, and tail immersion tests of nociception via opioidergic and GABAergic mechanisms, curbs inflammatory edema, and is antipyretic in nature.

Effect of fennel on primary dysmenorrhea: a systematic review and meta-analysis.

BACKGROUND: One of the most common complaints for women is dysmenorrhea. Several studies investigated the treatment effects of medicinal plants on primary dysmenorrhea. OBJECTIVES: This systematic review and meta-analysis investigates the effect of Foeniculum vulgare (Fennel) on pain in primary dysmenorrhea in comparison to non-steroidal anti-inflammatory drugs such as mefenamic acid. METHODS: PubMed, EMBASE, EBSCO Web of Science, Scopus, Cochrane library, Cochrane Central Register of Controlled Trials (CENTRAL), Science Direct, ProQuest, ISI Web of Science, Google Scholar, Magiran, SID, Iran Medex, and Irandoc were searched up to January 2019. Quality assessment of clinical trials was conducted using Jadad scoring system. Totally, 12 studies were entered in the meta-analysis. I 2 was calculated to determine heterogeneity. Fixed effects and/or random effects models were applied. RESULTS: Meta-analysis of these trials showed that F. vulgare intake decreased significantly the intensity of dysmenorrhea compared to the placebo (SMD -0.632; CI: -0.827 to -0.436; p<0.001; heterogeneity p=0.807; I 2=0%; fixed effect model; seven articles). However, the effect of Mefenamic acid with F. vulgare was not different from each other (SMD=-0.214; CI: -0.446 to 0.017; p=0.07; heterogeneity p=0.58; I 2=0%; fixed effect model; six trials). CONCLUSION: The F. vulgare alleviates dysmenorrhea. Regarding the same effect of F. vulgare with NSAIDs, it is highly recommend to the women suffered from dysmenorrhea specifically the ones who have high tendency toward herbal medicine.

A novel gabapentin analogue assuages neuropathic pain response in chronic sciatic nerve constriction model in rats.

Gabapentin (GBP) is an established drug that has been used in the management of symptoms of neuropathy but it is associated with unwanted side effects such as sedation and motor incoordination. The goal of the study was to find out a drug with greater efficacy and safety for the treatment of neuropathic pain. Our previously synthesized GABA analogue (Gabapentsal, GPS) was tested (25-100 mg/kg, i.p) in chronic constriction injury (CCI) induced nociceptive model of static allodynia, dynamic allodynia, thermal hyperalgesia, mechanical hyperalgesia and cold allodynia in rats (Sprague Dawley). Open field and rotarod tests were performed to assess the impact of GPS on the motor performance of the animals. GBP (100 mg/kg, i.p) was used as a standard for comparison. GPS dose dependently reduced static (P <0.001) and dynamic allodynia (P <0.001), thermal hyperalgesia (P <0.001), mechanical hyperalgesia (P < 0.001) and cold allodynia (P < 0.001). In comparison to GBP, GPS failed to alter any significantly the motor performance of rats in both the open field and rotarod assays. These results suggest that GPS is effective in alleviating nociception in CCI neuropathic pain model but free from the side effect of motor discoordination seen in the treatment with GBP. In conclusion, GPS may prove to be a prospectively more effective and safer option in the management of neuropathic syndromes.

Selected Thiadiazine-Thione Derivatives Attenuate Neuroinflammation in Chronic Constriction Injury Induced Neuropathy.

Neuropathic pain refers to a lesion or disease of peripheral and/or central somatosensory neurons and is an important body response to actual or potential nerve damage. We investigated the therapeutic potential of two thiadiazine-thione [TDT] derivatives, 2-(5-propyl-6-thioxo-1, 3, 5-thiadiazinan-3-yl) acetic acid [TDT1] and 2-(5-propyl-2-thioxo-1, 3, 5-thiadiazinan-3-yl) acetic acid [TDT2] against CCI (chronic constriction injury)-induced neuroinflammation and neuropathic pain. Mice were used for assessment of acute toxicity of TDT derivatives and no major toxic/bizarre responses were observed. Anti-inflammatory activity was assessed using the carrageenan test, and both TDT1 and TDT2 significantly reduced carrageenan-induced inflammation. We also used rats for the induction of CCI and performed allodynia and hyperalgesia-related behavioral tests followed by biochemical and morphological analysis using RT-qPCR, immunoblotting, immunohistochemistry and immunofluorescence. Our findings revealed that CCI induced clear-cut allodynia and hyperalgesia which was reversed by TDT1 and TDT2. To determine the function of TDT1 and TDT2 in glia-mediated neuroinflammation, Iba1 mRNA and protein levels were measured in spinal cord tissue sections from various experimental groups. Interestingly, TDT1 and TDT2 substantially reduced the mRNA expression and protein level of Iba1, implying that TDT1 and TDT2 may mitigate CCI-induced astrogliosis. In silico molecular docking studies predicted that both compounds had an effective binding affinity for TNF-α and COX-2. The compounds interactions with the proteins were dominated by both hydrogen bonding and van der Waals interactions. Overall, these results suggest that TDT1 and TDT2 exert their neuroprotective and analgesic potentials by ameliorating CCI-induced allodynia, hyperalgesia, neuroinflammation and neuronal degeneration in a dose-dependent manner.

Hydroalcoholic Extract of Anchusa Italica Protects Global Cerebral Ischemia-Reperfusion Injury Via a Nitrergic Mechanism.

INTRODUCTION: In stroke models, Inducible Nitric Oxide Synthase (iNOS) expression initiates cellular toxicity due to excessive Nitric Oxide (NO) generation. Anchusa italica is a medicinal herb with anti-inflammatory, antioxidant and neuroprotective properties. This study evaluated the antioxidant activity and NOS mRNA expression of the Hydroalcoholic Extract Of Anchusa Italica (HEAI) in an experimental stroke model in rats. METHODS: The stroke model was induced by bilateral occlusion of both common carotid arteries for 60 min. Twenty-four hours after surgery, HEAI (50 and 100 mg/kg i.p.) was injected daily for 10 consecutive days. mRNA expression levels of NOS subtypes and hippocampal Brain-Derived Neurotrophic Factor (BDNF) were studied using real-time PCR. Besides, hippocampal tissue plus serum concentrations of NO and Malondialdehyde (MDA) were measured. RESULTS: HEAI decreased MDA in both serum and hippocampal tissue and also reduced serum NO levels. Additionally, in the HEAI-treated groups, a down-regulation of iNOS mRNA expression, and an up-regulation of BDNF mRNA expression were observed. CONCLUSION: The results indicated that the administration of HEAI even after the onset of ischemia protects the brain from free radical injury and inflammation via a down-regulation of iNOS expression inhibiting NO production and an up-regulation of BDNF mRNA.

Inflammasome Signaling and Other Factors Implicated in Atherosclerosis Development and Progression.

Chronic inflammation plays an extensive role in the onset and progression of metabolic disorders such as atherosclerosis, type 2 diabetes, gout and obesity. Atherosclerosis accounts for up to 70% mortality in patients with type 2 diabetes and is also a chronic condition that causes atrial stenosis due to a lipometabolism imbalance. The purpose of this article is to consider the inflammatory factors implicated in atherosclerosis and their role in the development and progression of this vascular disease. The inflammasome signaling pathway is an important inflammatory mechanism involved in the development of atherosclerosis. The most important inflammasome pathway in this respect is the NLRP3 inflammasome (Nucleotide-binding oligomerization domain (NOD)-like receptor with a pyrin domain 3), whose activation leads to the generation of important inflammatory cytokines including interleukins 1ß and 18 (IL-1ß and 18). The activities of these mature cytokines and inflammatory factors produced by other inflammatory pathways lead to arterial inflammation and eventually arterial occlusion, which can result in life-threatening complications such as myocardial infarction and stroke. Therefore, it is essential to seek out more precise mechanisms for the activation of inflammasomes and other inflammatory pathways for the development of therapeutic strategies of atherosclerosis.

Mechanisms of Medicinal Plant Activity on Nitric Oxide (NO) Bioavailability as Prospective Treatments for Atherosclerosis.

BACKGROUND AND OBJECTIVE: Atherosclerosis is one of the leading causes of human morbidity globally and reduced bioavailability of vascular nitric oxide (NO) has a critical role in the progression and development of the atherosclerotic disease. Loss of NO bioavailability, for example via a deficiency of the substrate (L-arginine) or cofactors for endothelial nitric oxide synthase (eNOS), invariably leads to detrimental vascular effects such as impaired endothelial function and increased smooth muscle cell proliferation, deficiency of the substrate (Larginine) or cofactors for eNOS. Various medicinal plants and their bioactive compounds or secondary metabolites with fewer side effects are potentially implicated in preventing cardiovascular disease by increasing NO bioavailability, thereby ameliorating endothelial dysfunction. In this review, we describe the most notable medicinal plants and their bioactive compounds that may be appropriate for enhancing NO bioavailability, and treatment of atherosclerosis. METHODS: The material in this article was obtained from noteworthy scientific databases, including Web of Science, PubMed, Science Direct, Scopus and Google Scholar. RESULTS: Medicinal plants and their bioactive compounds influence NO production through diverse mechanisms including the activation of the nuclear factor kappa B (NF-κB) signaling pathway, activating protein kinase C (PKC)-α, stimulating protein tyrosine kinase (PTK), reducing the conversion of nitrite to NO via nitrate-nitrite reduction pathways, induction of eNOS, activating the phosphatidylinositol 3-kinase (PI3K)/serine threonine protein kinase B (AKT) (PI3K/AKT/eNOS/NO) pathway and decreasing oxidative stress. CONCLUSION: Medicinal plants and/or their constituent bioactive compounds may be considered as safe therapeutic options for enhancing NO bioavailability and prospective preventative therapy for atherosclerosis.

Review of Phytochemical Compounds as Antiviral Agents Against Arboviruses from the Genera Flavivirus and Alphavirus.

Arboviruses are a diverse group of viruses that are among the major causes of emerging infectious diseases. Arboviruses from the genera flavivirus and alphavirus are the most important human arboviruses from a public health perspective. During recent decades, these viruses have been responsible for millions of infections and deaths around the world. Over the past few years, several investigations have been carried out to identify antiviral agents to treat these arbovirus infections. The use of synthetic antiviral compounds is often unsatisfactory since they may raise the risk of viral mutation; they are costly and possess either side effects or toxicity. One attractive strategy is the use of plants as promising sources of novel antiviral compounds that present significant inhibitory effects on these viruses. In this review, we describe advances in the exploitation of compounds and extracts from natural sources that target the vital proteins and enzymes involved in arbovirus replication.

Effective Antiviral Medicinal Plants and Biological Compounds Against Central Nervous System Infections: A Mechanistic Review.

BACKGROUND AND OBJECTIVE: Infectious diseases are amongst the leading causes of death in the world and central nervous system infections produced by viruses may either be fatal or generate a wide range of symptoms that affect global human health. Most antiviral plants contain active phytoconstituents such as alkaloids, flavonoids, and polyphenols, some of which play an important antiviral role. Herein, we present a background to viral central nervous system (CNS) infections, followed by a review of medicinal plants and bioactive compounds that are effective against viral pathogens in CNS infections. METHODS: A comprehensive literature search was conducted on scientific databases including: PubMed, Scopus, Google Scholar, and Web of Science. The relevant keywords used as search terms were: "myelitis", "encephalitis", "meningitis", "meningoencephalitis", "encephalomyelitis", "central nervous system", "brain", "spinal cord", "infection", "virus", "medicinal plants", and "biological compounds". RESULTS: The most significant viruses involved in central nervous system infections are: Herpes Simplex Virus (HSV), Varicella Zoster Virus (VZV), West Nile Virus (WNV), Enterovirus 71 (EV71), Japanese Encephalitis Virus (JEV), and Dengue Virus (DENV). The inhibitory activity of medicinal plants against CNS viruses is mostly active through prevention of viral binding to cell membranes, blocking viral genome replication, prevention of viral protein expression, scavenging reactive Oxygen Species (ROS), and reduction of plaque formation. CONCLUSION: Due to the increased resistance of microorganisms (bacteria, viruses, and parasites) to antimicrobial therapies, alternative treatments, especially using plant sources and their bioactive constituents, appear to be more fruitful.

Neurotransmitter, Antioxidant and Anti-neuroinflammatory Mechanistic Potentials of Herbal Medicines in Ameliorating Autism Spectrum Disorder.

BACKGROUND: Autism spectrum disorder (ASD) is a neurodevelopmental issue that disrupts behavior, nonverbal communication, and social interaction, impacting all aspects of an individual's social development. The underlying origin of autism is unclear, however, oxidative stress, as well as serotonergic, adrenergic and dopaminergic systems are thought to be implicated in ASD. Despite the fact that there is no effective medication for autism, current pharmacological treatments are utilized to ameliorate some of the symptoms such as selfmutilation, aggression, repetitive and stereotyped behaviors, inattention, hyperactivity, and sleep disorders. METHODS: In accord with the literature regarding the activity of herbal medicines on neurotransmitter function, we aimed to review the most worthy medicinal herbs possessing neuroprotective effects. RESULTS: Based on the outcome, medicinal herbs such as Zingiber officinale, Astragalus membranaceu, Ginkgo biloba, Centella asiatica and Acorus calamus, have antioxidant activity, which can influence neurotransmitter systems and are potentially neuroprotective. CONCLUSION: Consequently, these herbs, in theory at least, appear to be suitable candidates within an overall management strategy for those on the autism spectrum.

Efficacy of a topical gabapentin gel in a cisplatin paradigm of chemotherapy-induced peripheral neuropathy.

BACKGROUND: Chemotherapy induced peripheral neuropathy (CIPN) has been attributed to chemotherapeutic agents such as cisplatin which adversely affect disease outcome leading to increased cancer related morbidity. The clinical efficacy of systemic gabapentin in neuropathic pain management is limited by central side-effects in addition to a scarceness of conclusive evidence of its efficacy in CIPN management. The topical route therefore may provide a relatively safe alternative for neuropathic pain treatment in general and CIPN in particular. METHODS: Cisplatin induced neuropathic nociception was established in rats after a single weekly cisplatin injection (3.0 mg/kg, intraperitoneally) for 4 weeks. The evoked neuropathic sensation of allodynia was assessed by plantar application of von Frey monofilaments as the paw withdrawal threshold (PWT), whereas the expression of heat-hypoalgesia was determined on a hot-plate as paw withdrawal latency (PWL). Gabapentin gel (10% w/w) was applied three-times daily on the hind paws while in a concurrent systemic study, gabapentin was administered daily (75 mg/kg, intraperitoneally) for 4 weeks. To assess any evidence of neurological adverse symptoms of cisplatin and the central side-effect propensity of systemic or topical gabapentin, evaluation of motor coordination (rotarod test) and gait (footprint analysis) were performed. RESULTS: Cisplatin invoked a progressive development of neuropathic hind paw allodynia (decreased PWT, days 7-28) and heat hypoalgesia (increased PWL, days 21-28). Topical gabapentin significantly delayed the expression of both allodynia on protocol days 21 and 28 and heat-hypoalgesia (day 28). Systemic gabapentin displayed a comparative anti-neuropathic predisposition through a sustained suppression of tactile allodynia on days 14 and 21-28 as well as thermal hypoalgesia (days 21 and 28). Systemic gabapentin also impaired motor coordination and gait thus affirming its clinically documented central side effects, but these outcomes were not evident after topical treatment. CONCLUSIONS: Both topical and systemic gabapentin exhibit a propensity to attenuate CIPN in a cisplatin paradigm. Gabapentin applied topically may therefore provide an adjunctive or alternative route for CIPN management upon cessation of systemic medications due to intolerable side-effects.