Effects of linalool on glutamate release and uptake in mouse cortical synaptosomes

Gut-Brain-axis: effect of basil oil on the gut microbiota and its contribution to the anticonvulsant properties

BACKGROUND

Epilepsy is a chronic neurological condition that disrupts the normal functioning of the brain and it is characterized by seizures. Research suggests the involvement of the Gut-Brain axis in epilepsy. This study seeks to determine the role of the gut microbiota in the anticonvulsant effect of basil oil (BO) using antibiotic-depleted and altered germ-free mice against naïve mice in Pentylenetetrazole (PTZ) induced seizure model. There is an ever growing interest in improvement of treatment outcomes in epilepsy and also in the development of newer therapeutic options, especially in the population of patients that do not attain seizure relief from available antiseizure medications (ASMs). According to research, gut microbiota can alter brain function and development. Increasing evidence suggests disrupting the delicate symbiotic balance existing between the gut and brain results in disease conditions. Also, the oil from Ocimum basilicum L., (BO) has been proven scientifically to significantly block clonic seizures induced by PTZ and picrotoxin in seizure models.

METHODS

The microbiota of mice were depleted or altered by administering cocktail antibiotics and individual antibiotics respectively. DNA was isolated from mouse stool, and then the 16S ribosomal ribonucleic acid (16S rRNA) gene was quantitatively amplified using reverse transcription-polymerase chain reaction (RT-PCR). Amplicons were sequenced to determine the phylogenetic make-up of the bacteria involved. Metabolic profiles of the serum and stool of mice were determined using Proton (1H) Nuclear Magnetic Resonance (NMR) spectroscopy.

RESULTS

Cocktail antibiotic pre-treatment significantly reversed the anticonvulsant effect of BO by increasing frequency and duration of seizures but did not affect latency to seizure. In mice pre-treated with single antibiotics, the anticonvulsant effect of BO was lost as latency to seizures, frequency and duration of seizures increased compared to mice that received only BO. Assessment of the phylogenetic make-up of the microbiota in antibiotic pre-treated mice showed a distorted composition of the microbiota compared to the control group.

CONCLUSION

Depletion of the microbiota significantly reversed the anticonvulsant actions of BO. The concentrations of short chain fatty acids (SCFAs) was higher in stool than in the serum of the mice. Administration of BO probably does not influence the microbial composition within the mouse microbiota. The elevated ratio of Firmicutes to Bacteroidetes in microbiota-depleted groups might have contributed to the reversal of anticonvulsant actions of BO.

Hirami lemon (Citrus reticulata var. depressa) modulates the gut-brain axis in a chronic mild stress-induced depression mouse model

Citrus reticulata var. depressa, commonly known as Hirami lemon, is a native citrus species found in Taiwan and Okinawa islands of Japan. While several Citrus species are known to possess antidepressant activity by modulating the gut microbiota, the antidepressant effect of Hirami lemon and its underlying mechanisms have not been thoroughly investigated. In this study, we explored the potential antidepressant efficacy of the fruit extract (CD) and the essential oil (CDE) from Hirami lemon peel using a chronic mild stress (CMS)-induced mouse model and analyzed the association of gut microbiome changes. Our findings revealed that mice subjected to CMS exhibited anxiety- and depression-like behaviors as assessed by elevated plus-maze and forced swimming tests, respectively. Significantly, oral administration of CDE and CD notably reversed CMS-induced depression- and anxiety-like behaviors in CMS-induced mice. Moreover, compared to the non-stressed group, CMS significantly altered the gut microbiome, characterized by highly diverse bacterial communities, reduced Bacteroidetes, and increased Firmicutes. However, oral administration of CDE and CD restored gut microbiota dysbiosis. We also performed a qualitative analysis of CD and CDE using UPLC-MS and GC-MS, respectively. The CD contained 25 compounds, of which 3 were polymethoxy flavones and flavanones. Three major compounds, nobiletin, tangeretin and hesperidin, accounted for 56.88% of the total relative peak area. In contrast, the CDE contained 11 terpenoids, of which 8 were identified as major compounds, with D-limonene (45.71%) being the most abundant, followed by γ-terpinene (34.65%), linalool (6.46%), p-cymene (2.57%), α-terpineol (2.04%), α-pinene (1.89%), α-terpinolene (1.46%), and β-pinene (1.16%), accounting for 95.94% of the total oil. In conclusion, our study demonstrated the potential of Hirami lemon as a source of natural antidepressant agents for the prevention and treatment of major depressive disorders.

Aromatherapy for the brain: Lavender's healing effect on epilepsy, depression, anxiety, migraine, and Alzheimer's disease: A review article

Neurological diseases affect the nervous system, including the brain, spinal cord, cranial nerves, nerve roots, autonomic nervous system, neuromuscular junctions, and muscles. Herbal medicine has long been used to cure these diseases. One of these plants is lavender, which is composed of various compounds, including terpenes, such as linalool, limonene, triterpenes, linalyl acetate, alcohols, ketones, polyphenols, coumarins, cineole, and flavonoids. In this review, the literature was searched using scientific search engines and databases (Google Scholar, Science Direct, Scopus, and PubMed) for papers published between 1982 and 2020 via keywords, including review, lavender, and neurological disorders. This plant exerts its healing effect on many diseases, such as anxiety and depression through an inhibitory effect on GABA. The anti-inflammatory effects of this plant have also been documented. It improves depression by regulating glutamate receptors and inhibiting calcium channels and serotonergic factors, such as SERT. Its antiepileptic mechanism is due to an increase in the inhibitory effect of GABA and potassium current and a decrease in sodium current. Therefore, many vegetable oils are also used in herbal medicine. In this review, the healing effect of lavender on several neurological disorders, including epilepsy, depression, anxiety, migraine, and Alzheimer's disease was investigated. All findings strongly support the traditional uses of lavender. More clinical studies are needed to investigate the effect of the plants' pharmacological active constituents on the treatment of life-threatening diseases in humans. The limitations of this study are the low quality and the limited number of clinical studies. Different administration methods of lavender are one of the limitations of this review.

A review of the bioactive components and pharmacological properties of Lavandula species

Lavandula species is a flowering plant that is common in Europe and across the Mediterranean. Lavender has many health benefits for humans. In addition to its use in herbal medicine, it is widely used in the fields of cosmetics, perfumes, foods, and aromatherapy. Google Scholar, PubMed, Scopus, and Web of Science were used to search for relevant material on the phytochemical ingredients, the pharmacologic effects of the ingredients, and the mechanism of action of the Lavandula species identified. These materials were reviewed in order to have access to important updates about the Lavandula species. Lavender as referred to in English contains essential oils, anthocyanins, phytosterols, sugars, minerals, coumaric acid, glycolic acid, valeric acid, ursolic acid, herniarins, coumarins, and tannins. It has been used to treat colic and chest ailments, worrisome headaches, and biliousness, and in cleaning wounds. It has antifungal, antibacterial, neurologic, antimicrobial, anti-parasitic, anti-diabetic, and analgesic effects among others. Lavandula species has prospects for various biological applications, especially with its dermatological application. Advances in drug development would enable characterization of various bioactive constituents; thus, its development and application can have a more positive impact on humanity. Here, we highlighted updated information on the history, distribution, traditional uses, phytochemical components, pharmacology, and various biological activities of Lavandula species.

Anxiolytic effect of Anthemis nobilis L. (roman chamomile) and Citrus reticulata Blanco (tangerine) essential oils using the light-dark test in zebrafish (Danio rerio)

ETHNOPHARMACOLOGICAL RELEVANCE

The anxiety disorders are the most prevalent mental health condition, and anxiety is considered the sixth cause of disability surpassing diabetes mellitus, chronic obstructive pulmonary disease, and osteoarthritis. Besides, the COVID-19 pandemic provided an increase in the number of psychiatric diseases diagnosis in all social layers around the world. About 55%-94% of patients diagnosed with anxiety disorders are treated with benzodiazepines, meanwhile benzodiazepines can promote several adverse effects. In this way, alternative therapies, such as essential oils may offer significant benefits in the treatment of patients with anxiety disorders. However, the anxiolytic effect of these essential oils must be proper evaluated appropriate as well as the suitable dosage and side effect need further research.

AIM OF THE STUDY

The aim was to evaluate the anxiolytic effect of Roman chamomile (Anthemis nobilis L.) and tangerine (Citrus reticulata Blanco) essential oils using the light-dark test in adult zebrafish (Danio rerio).

MATERIAL AND METHODS

Both essential oils were analyzed by GC-MS and the major compounds were identified. The anxiolytic effect was evaluated by light-dark test in adult zebrafish.

RESULTS

The results showed that roman chamomile essential oil has anxiolytic effect in adult zebrafish, whereas tangerine essential oil tends to reduce anxiety The major compounds of tangerine essential oil were limonene and γ-terpinene, and the major compounds of roman chamomile were pentadecyl-3-methyl-2-butenoate, hexadecyl-3-methyl-2-butenoate, 1-piperidinol and trans-1-ethyl-3-methyl-cyclopentane.

CONCLUSIONS

The present study demonstrated that this anxiolytic effect may be attributed to the synergistic effect of the compounds present in roman chamomile essential oil, particularly the major compounds. The roman chamomile essential oil at the highest concentration showed anxiolytic effect. The tangerine essential oil showed a tendency to reduce anxiety, but it was not statistically significative. In addition, roman chamomile and tangerine essential oils did not cause cause alteration in locomotion activity and exploratory ability of the fish.

Mechanistic Insights into the Neuroprotective Potential of Sacred Ficus Trees

Ficus religiosa (Bo tree or sacred fig) and Ficus benghalensis (Indian banyan) are of immense spiritual and therapeutic importance. Various parts of these trees have been investigated for their antioxidant, antimicrobial, anticonvulsant, antidiabetic, anti-inflammatory, analgesic, hepatoprotective, dermoprotective, and nephroprotective properties. Previous reviews of Ficus mostly discussed traditional usages, photochemistry, and pharmacological activities, though comprehensive reviews of the neuroprotective potential of these Ficus species extracts and/or their important phytocompounds are lacking. The interesting phytocompounds from these trees include many bengalenosides, carotenoids, flavonoids (leucopelargonidin-3-O-β-d-glucopyranoside, leucopelargonidin-3-O-α-l-rhamnopyranoside, lupeol, cetyl behenate, and α-amyrin acetate), flavonols (kaempferol, quercetin, myricetin), leucocyanidin, phytosterols (bergapten, bergaptol, lanosterol, β-sitosterol, stigmasterol), terpenes (α-thujene, α-pinene, β-pinene, α-terpinene, limonene, β-ocimene, β-bourbonene, β-caryophyllene, α-trans-bergamotene, α-copaene, aromadendrene, α-humulene, alloaromadendrene, germacrene, γ-cadinene, and δ-cadinene), and diverse polyphenols (tannin, wax, saponin, leucoanthocyanin), contributing significantly to their pharmacological effects, ranging from antimicrobial action to neuroprotection. This review presents extensive mechanistic insights into the neuroprotective potential, especially important phytochemicals from F. religiosa and F. benghalensis. Owing to the complex pathophysiology of neurodegenerative disorders (NDDs), the currently existing drugs merely alleviate the symptoms. Hence, bioactive compounds with potent neuroprotective effects through a multitarget approach would be of great interest in developing pharmacophores for the treatment of NDDs.

A combination of linalool and linalyl acetate synergistically alleviates imiquimod-induced psoriasis-like skin inflammation in BALB/c mice

Introduction: Psoriasis is a chronic inflammatory skin disorder characterized by keratinocyte hyperproliferation and differentiation with increased immune cell infiltration. The anti-psoriatic effect of lavender oil has been reported. However, its phytoconstituents, linalool (L) and linalyl acetate (LA), showed a distinctive affinity with psoriasis targets.

Objectives: This investigation was aimed to determine the combined effect of L and LA in ameliorating psoriasis-like skin inflammation and its safety in long-term topical uses.

Methods: The combined effect of L and LA was compared with their individual effects. The anti-psoriatic activity was performed using imiquimod (IMQ)-induced psoriasis in BALB/c mice and evaluated to reduce PASI and CosCam scores and Th-1 and Th-17 cell-specific cytokine levels. The acute and repeated dose dermal toxicities were investigated as per the OECD guidelines.

Results: L and LA combination (LLA) in the 1:1 w/w ratio at 2% concentration showed a synergistic effect. The combination showed 76.31% and 71.29% recovery in PASI and CosCam Scores; however, L2% and LA2% showed 64.28% and 47.61% recovery in PASI and 64.75 and 56.76% recovery in CosCam scores, respectively. It showed >90% and >100% recovery in Th-17 and Th-1 cell-specific cytokines, respectively, and restored epidermal hyperplasia and parakeratosis toward normal compared with psoriatic mice. A marked reduction in NF-κB, cck6, and the IL-17 expression was also observed in the LLA-treated group. This combination was safe in a therapeutically effective dose for 28 days as no significant changes were observed in organ and body weights, liver and kidney parameters, and differential leukocyte counts.

Conclusion: This study proves the synergy between L and LA in a 1:1 w/w ratio at 2% in the treatment of psoriasis-like skin inflammation and provides strong scientific evidence for its safe topical use.

Multi-Target Approach of Murraya koenigii Leaves in Treating Neurodegenerative Diseases

Neurodegenerative diseases (NDs) mainly affect neurons and gradually lead to a loss of normal motor and cognitive functions. Atypical protein homeostasis-misfolding, aggregations and accumulations, oxidative stress, inflammation, and apoptosis-are common features in most NDs. To date, due to the complex etiology and pathogenesis of NDs, no defined treatment is available. There has been increasing interest in plant extracts as potential alternative medicines as the presence of various active components may exert synergistic and multi-pharmacological effects. Murraya koenigii (Rutaceae) is utilized in Ayurvedic medicine for various ailments. Pharmacological studies evidenced its potential antioxidant, anti-inflammatory, anticancer, hepatoprotective, immunomodulatory, antimicrobial, and neuroprotective activities, among others. In line with our interest in exploring natural agents for the treatment of neurodegenerative diseases, this review presents an overview of literature concerning the mechanisms of action and the safety profile of significant bioactive components present in M. koenigii leaves to support further investigations into their neuroprotective therapeutic potential.

Rewarding effect of ethanol-induced conditioned place preference in mice: Effect of the monoterpenoid linalool

Alcohol addiction is a chronic relapsing disease that is progressive and has severe detrimental health outcomes. The use of natural products has become popular for the treatment of side effects of drugs and substance abuse. Linalool is a monoterpenoid that exhibits several effects on the central nervous system. Linalool was identified to have beneficial effects on different mechanisms that are relevant in drug addiction or substance use disorder. The primary aim of the present study was to evaluate the therapeutic effect of linalool on the rewarding properties of alcohol in mice. Conditioned place preference (CPP) was established by intraperitoneal (i.p.) injection of ethanol (2 g/kg) during an 8-day conditioning trial. The effects of acamprosate and linalool on the rewarding properties of ethanol were tested in mice who received linalool (12.5, 25, and 50 mg/kg, i.p.) and acamprosate (300 mg/kg, i.p.) 30 min before each ethanol injection. CPP was extinguished by repeated testing, throughout which conditioned mice were administered daily linalool. Mice were lastly examined for reinstatement provoked by i.p. administration of single low-dose ethanol (0.4 g/kg, i.p.). Treatment with linalool reduced the acquisition and reinstatement, and precipitated the extinction of ethanol-induced CPP in mice. Acquisition and reinstatement of alcohol-induced CPP were significantly reduced by acamprosate, which also precipitated extinction. Ethanol alone and the combination with linalool or acamprosate did not alter locomotor activity. The results of this study suggest that linalool may have pharmacological effects for the treatment of alcohol addiction. In addition, further investigation is required to fully explore the benefits and possible adverse effects of linalool on alcohol addiction.

Neuroprotective effects of Coriandrum sativum and its constituent, linalool: A review

Objective:

Coriander (Coriandrum sativum L.) is an annual herb belonging to the Apiaceae (Umbellifera) family that is used as food additives traditionally. This plant is called “Geshniz” in Persian and is native to Mediterranean regions but it is currently cultivated in several countries. All parts of coriander are edible and have been traditionally used to treat different disorders, including digestive problems, flatulence, diarrhea, colic and other gastrointestinal diseases.

Materials and Methods:

The databases PubMed, Web of Science, Google Scholar and Scopus were considered. The search terms were “Coriandrum sativum” or “linalool” and “anti-anxiety”, “sedative”, “antioxidant effect”, “anticonvulsant” and “neuroprotective effect”.

Results:

Antioxidant, diuretic, cholesterol lowering, anxiolytic, sedative-hypnotic and anticonvulsant activities were reported for the seeds and leaves of the plant. Furthermore, linalool as the main component of coriander has different neuropharmacological effects, including anti-anxiety, sedative, anticonvulsant and anti-Alzheimer’s disease activities.

Conclusion:

Various neuropharmacological effects of C. sativum and its component which have antioxidant and anti-inflammatory effects, have been summarized in the current review article.

Neuroprotective Potential of Limonene and Limonene Containing Natural Products

Limonene is a monoterpene confined to the family of Rutaceae, showing several biological properties such as antioxidant, anti-inflammatory, anticancer, antinociceptive and gastroprotective characteristics. Recently, there is notable interest in investigating the pharmacological effects of limonene in various chronic diseases due to its mitigating effect on oxidative stress and inflammation and regulating apoptotic cell death. There are several available studies demonstrating the neuroprotective role of limonene in neurodegenerative diseases, including Alzheimer's disease, multiple sclerosis, epilepsy, anxiety, and stroke. The high abundance of limonene in nature, its safety profile, and various mechanisms of action make this monoterpene a favorable molecule to be developed as a nutraceutical for preventive purposes and as an alternative agent or adjuvant to modern therapeutic drugs in curbing the onset and progression of neurodegenerative diseases. This manuscript presents a comprehensive review of the available scientific literature discussing the pharmacological activities of limonene or plant products containing limonene which attribute to the protective and therapeutic ability in neurodegenerative disorders. This review has been compiled based on the existing published articles confined to limonene or limonene-containing natural products investigated for their neurotherapeutic or neuroprotective potential. All the articles available in English or the abstract in English were extracted from different databases that offer an access to diverse journals. These databases are PubMed, Scopus, Google Scholar, and Science Direct. Collectively, this review emphasizes the neuroprotective potential of limonene against neurodegenerative and other neuroinflammatory diseases. The available data are indicative of the nutritional use of products containing limonene and the pharmacological actions and mechanisms of limonene and may direct future preclinical and clinical studies for the development of limonene as an alternative or complementary phytomedicine. The pharmacophore can also provide a blueprint for further drug discovery using numerous drug discovery tools.

Activity of Selected Group of Monoterpenes in Alzheimer's Disease Symptoms in Experimental Model Studies-A Non-Systematic Review

Alzheimer's disease (AD) is the leading cause of dementia and cognitive function impairment. The multi-faced character of AD requires new drug solutions based on substances that incorporate a wide range of activities. Antioxidants, AChE/BChE inhibitors, BACE1, or anti-amyloid platelet aggregation substances are most desirable because they improve cognition with minimal side effects. Plant secondary metabolites, used in traditional medicine and pharmacy, are promising. Among these are the monoterpenes-low-molecular compounds with anti-inflammatory, antioxidant, enzyme inhibitory, analgesic, sedative, as well as other biological properties. The presented review focuses on the pathophysiology of AD and a selected group of anti-neurodegenerative monoterpenes and monoterpenoids for which possible mechanisms of action have been explained. The main body of the article focuses on monoterpenes that have shown improved memory and learning, anxiolytic and sleep-regulating effects as determined by in vitro and in silico tests-followed by validation in in vivo models.

Linalool attenuates acquisition and reinstatement and accelerates the extinction of nicotine-induced conditioned place preference in male mice

Background: Nicotine is the addictive agent in tobacco products. The monoterpene linalool is the main ingredient in the essential oils of various aromatic plants. It has previously been demonstrated that linalool has beneficial effects on some mechanisms that are important in drug addiction.Objectives: The goal of the current study was to investigate the effect of linalool on nicotine-induced conditioned place preference (CPP) in male mice.Methods: CPP was induced by administering intraperitoneal (i.p.) injection of nicotine (0.5 mg/kg) during the conditioning phase. The effects of nicotinic acetylcholine receptor partial agonist varenicline and linalool on the rewarding characteristics of nicotine were tested in mice with administration of linalool (12.5, 25, and 50 mg/kg, i.p.), varenicline (2 mg/kg, i.p.) or saline 30 minutes before nicotine injection. CPP was extinguished by repeated testing, during which conditioned mice were administered varenicline and linalool every day. One day after the last extinction trial, mice that received linalool, varenicline or saline 30 minutes before a priming injection of nicotine (0.1 mg/kg, i.p.) were immediately tested for reinstatement of CPP.Results: Linalool attenuated nicotine acquisition (50 mg/kg, p < .01) and reinstatement (25 and 50 mg/kg, respectively p < .05, p < .01) and accelerated the extinction of nicotine-induced CPP (50 mg/kg, p < .05). Linalool exhibited similar effects on the reference drug varenicline in the CPP phases.Conclusion: These results suggest that linalool may be helpful as an adjuvant for the treatment of nicotine use disorder.

The effects of linalool acupoint application therapy on sleep regulation

The Shenque acupoint is located in the umbilicus of the human body. In the human body meridians, the Shenque acupoint can regulate body functions. The Shenque acupoint was one of the important acupuncture acupoints for the treatment of insomnia. However, the effect of linalool applied at the Shenque acupoint to improve sleep was unknown. This study explored the hypnotic and sedative effects of the main component of lavender, linalool, on the Shenque acupoint of mice and rats. The effects on the sleep latency and sleep duration were studied with the supra-threshold dose of pentobarbital sodium, and the effects on the sleep rate were studied with the sub-threshold dose of pentobarbital sodium. In order to further study the feasibility and superiority of linalool administered at the Shenque acupoint, a pharmacokinetic study was carried out. The pharmacodynamic results showed that the mice and rats treated with linalool at Shenque had the highest sleep rate, the shortest sleep latency, and the longest sleep duration compared with other groups. The T max and t 1/2 of the LS were longer than those of the LO, and had the characteristics of sustained release. The relative bioavailability of LS was 323.0 ± 31.66%. This showed that the combination of linalool and the Shenque acupoint had greater medicinal effects. This development will provide a new direction for improving sleep.

Pain Control with Lavender Oil in Premature Infants: A Double-Blind Randomized Controlled Study

Objectives: Aromatherapy has become popular in pain control in recent years compared with other complementary methods. Lavender (Lavandula angustifolia Miller) is a fragrant essential oil used in aromatherapy for its antibacterial, antifungal, muscle-relaxing, and analgesic effects. The smell of lavender oil, known for its soothing effect on adults, has not been adequately investigated in regards to pain control in premature infants. The purpose of our study was to assign the effect of the scent of lavender oil on pain in preterm infants during heel lancing. Design: A double-blind randomized controlled clinical study. Settings/Location: The study was conducted in a third-level neonatal intensive care unit of Bezmialem Vakif University Hospital from March 2019 to November 2019. It consisted of two groups. Subjects: Sixty-one premature babies (24-37 weeks of gestation) were enrolled in the study. Interventions: Heel stick sampling for metabolic screening was used for both study groups. The interventions were performed by two experienced nurses. Heart rate, oxygen saturation, and the baby's facial expression were recorded by a camera 3 min before the intervention, during the sampling, and 3 min after the procedure. After collecting the data, the head researcher and the assistant researcher separately watched the videos and scored them by using the Premature Infant Pain Profile-Revised (PIPP-R). Outcome measures: The difference of pain scores (PIIP-R) between two groups. Results: There was a statistically significant difference between the two groups in terms of PIPP-R scores during and after the sampling (p = 0.008 and p = 0.03 respectively). The PIPP-R scores at the beginning of the procedure were not found to be significantly different between the groups (p > 0.05). Conclusions: Inhalation of lavender scent is effective in pain control in premature infants. It is safe and low cost; it does not interfere with medical care.

Pharmacological basis of the anxiolytic and antidepressant properties of Silexan®, an essential oil from the flowers of lavender

Silexan®, a proprietary essential oil manufactured by steam distillation from Lavandula angustifolia flowers showed pronounced anxiolytic effects in patients with subthreshold anxiety disorders and was also efficacious in patients with Generalized Anxiety disorder (GAD). Moreover, evidences for antidepressant-like properties of Silexan® have been observed in anxious patients suffering from comorbid depressive symptoms and in patients with mixed anxiety-depression disorder (ICD-10 F41.2). In accordance with the clinical data Silexan® is active in several behavioral models in rodents at rather low concentrations indicating potent anxiolytic and antidepressive properties. As possible mechanism of action a moderate inhibition of voltage dependent calcium channels (VDCC) has been found showing some similarities to the anxiolytic drug pregabalin. However, while pregabalin mainly inhibits P/Q-type channels by binding to a modulatory subunit, Silexan® moderately inhibits mainly T-type and N-type channels and to some extent P/Q-type channels. Unlike pregabalin Silexan® is free of hypnotic or sedative side effects and seems to be devoid of any abuse potential. With respect to its specific antidepressant like properties Silexan® improves several aspects of neuroplasticity which seems to be the common final pathway of all antidepressant drugs. As a potential mechanism of its effects on neuroplasticity an activation of the transcription factor CREB via activation of intracellular signaling kinases like PKA and MAPK has been found. Since the concentrations of Silexan® needed to inhibit VDCC function and to improve neuroplasticity are quite similar, the effects of Silexan® on PKA or MAPK could constitute a common intracellular signaling cascade leading to VDCC modulation as well as CREB activation and improved neuroplasticity.

History repeats itself: Role of characterizing flavors on nicotine use and abuse

The popularity of e-cigarettes has skyrocketed in recent years, and most vapers use flavored e-cigarette products. Consumption of flavored e-cigarettes exceeds that of combustible cigarettes and other tobacco products among adolescents, who are particularly vulnerable to becoming nicotine dependent. Flavorings have been used by the tobacco industry since the 17th century, but the use of flavors by the e-cigarette industry to create products with "characterizing" flavors (i.e. flavors other than tobacco or menthol) has sparked a public health debate. This review addresses the possibility that characterizing flavors make nicotine more appealing, rewarding and addictive. It also discusses ways in which preclinical and clinical studies could improve our understanding of the mechanisms by which flavors may alter nicotine reward and reinforcement. This article is part of the special issue on 'Contemporary Advances in Nicotine Neuropharmacology'.

Michelia Essential Oil Inhalation Increases Fast Alpha Wave Activity

Essential oils are volatile fragrance liquids extracted from plants, and their compound annual growth rate is expected to expand to 8.6% from 2019 to 2025, according to Grand View Research. Essential oils have several domains of application, such as in the food and beverage industry, in cosmetics, as well as for medicinal use. In this study, Michelia alba essential oil was extracted from leaves and was rich in linalool components as found in lavender and jasmine oil. The effects of inhaling michelia oil on human brainwaves still need to be elucidated. Ten male and ten female subjects were recruited. Thirty-two-channel electroencephalography was recorded. The raw data were spectrally analyzed for slow alpha, fast alpha, low beta, mid beta, and high beta activities. The results demonstrate that michelia leaf oil could reduce the alertness level observed by beta wave decrease and fast alpha wave activity increase. The inhalation of pure linalool showed virtually identical responses as the michelia oil inhalation. In conclusion, the sedative effects of michelia oil inhalation might originate from its major linalool component.

Anxiolytic Effect of Essential Oils and Their Constituents: A Review

Essential oils are usually used in aromatherapy to alleviate anxiety symptoms. In comparison to traditional drugs, essential oils have fewer side effects and more diversified application ways, including inhalation. This review provides a comprehensive overview of studies on anxiolytic effects of essential oils in preclinical and clinical trials. Most of the essential oils used in clinical studies have been proven to be anxiolytic in animal models. Inhalation and oral administration were two common methods for essential oil administration in preclinical and clinical trials. Massage was only used in the clinical trials, while intraperitoneal injection was only used in the preclinical trails. In addition to essential oils that are commonly used in aromatherapy, essential oils from many folk medicinal plants have also been reported to be anxiolytic. More than 20 compounds derived from essential oils have shown an anxiolytic effect in rodents, while two-thirds of them are alcohols and terpenes. Monoamine neurotransmitters, amino acid neurotransmitters, and the hypothalamic-pituitary-adrenal axis are thought to play important roles in the anxiolytic effects of essential oils.

Effects of lavender on anxiety: A systematic review and meta-analysis

BACKGROUND

Anxiety is one of the uprising psychiatric disorders of the last decades and lavender administration has been traditionally suggested as a possible treatment. The objective of this review is to assess the efficacy of lavender, in any form and way of administration, on anxiety and anxiety-related conditions.

METHODS

The PRISMA guidelines were followed. Retrieved data were qualitatively and quantitatively synthesized. Randomized Controlled Trials (RCTs) and Non-Randomized Studies (NRSs) which investigated the efficacy of lavender, in any form and way of administration, on patients with anxiety, involved in anxiety-inducing settings or undergoing anxiety-inducing activities, compared to any type of control, without language restrictions, were identified through electronic database searches. Medline via PubMed, Scopus, Web of Science, Cochrane Library, EMBASE, and Google Scholar were systematically searched. All databases were screened up to November 2018. Risk of bias was assessed with the Cochrane risk-of-bias tool and the following domains were considered: randomization, allocation sequence concealment, blinding, incomplete outcome data, selective outcome reporting, and other biases.

RESULTS

65 RCTs (7993 participants) and 25 NRSs (1200 participants) were included in the qualitative synthesis and 37 RCTs (3964 participants) were included in the quantitative synthesis. Overall, the qualitative synthesis indicated that 54 RCTs and 17 NRSs reported at least a significant result in favor of lavender use for anxiety. The quantitative synthesis showed that lavender inhalation can significantly reduce anxiety levels measured with any validated scale (Hedges' g = -0.73 [95% CI -1.00 to -0.46], p < 0.00001, 1682 participants), as well as state anxiety (Spielberger's state-trait anxiety inventory (STAI)-State mean difference = -5.99 [95% CI -9.39 to -2.59], p < 0.001, 901 participants) and trait anxiety (STAI-Trait mean difference = -8.14 [95% CI -14.44 to -1.84], p < 0.05, 196 participants). Lavender inhalation did not show a significant effect in reducing systolic blood pressure as a physiological parameter of anxiety. A significant effect in diminishing anxiety levels was also found in favor of the use of oral Silexan® 80 mg/die for at least 6 weeks (Hamilton Anxiety Scale mean difference = -2.90 [95% CI -4.86 to -0.95], p = 0.004, 1173 participants; Zung Self-rating Anxiety Scale mean difference = -2.62 [95% CI -4.84 to -0.39], p < 0.05, 451 participants) or of the administration of massage with lavender oil (Hedges' g = -0.66 [95% CI -0.97 to -0.35], p < 0.0001, 448 participants).

DISCUSSION

The most important limitation of this review is the low average quality of available studies on the topic. The majority of included RCTs were characterized by a high overall risk of bias. Another limitation regards the heterogeneity of study designs, especially with regard to non-oral ways of administration. Overall, oral administration of lavender essential oil proves to be effective in the treatment of anxiety, whereas for inhalation there is only an indication of an effect of reasonable size, due to the heterogeneity of available studies. Lavender essential oil administered through massage appears effective, but available studies are not sufficient to determine whether the benefit is due to a specific effect of lavender. Further high-quality RCTs with more homogeneous study designs are needed to confirm these findings. Available information outlines a safe profile for lavender-based interventions, although more attention should be paid to the collection and reporting of safety data in future studies. Considering these findings, since treatments with lavender essential oil generally seem safe, and, in the case of inhalation, also simple and inexpensive, they are a therapeutic option which may be considered in some clinical contexts.

OTHER

The present systematic review was not funded and was registered in PROSPERO under the following number: CRD42019130126.

Medicinal Properties of Cannabinoids, Terpenes, and Flavonoids in Cannabis, and Benefits in Migraine, Headache, and Pain: An Update on Current Evidence and Cannabis Science

BACKGROUND

Comprehensive literature reviews of historical perspectives and evidence supporting cannabis/cannabinoids in the treatment of pain, including migraine and headache, with associated neurobiological mechanisms of pain modulation have been well described. Most of the existing literature reports on the cannabinoids Δ⁹ -tetrahydrocannabinol (THC) and cannabidiol (CBD), or cannabis in general. There are many cannabis strains that vary widely in the composition of cannabinoids, terpenes, flavonoids, and other compounds. These components work synergistically to produce wide variations in benefits, side effects, and strain characteristics. Knowledge of the individual medicinal properties of the cannabinoids, terpenes, and flavonoids is necessary to cross-breed strains to obtain optimal standardized synergistic compositions. This will enable targeting individual symptoms and/or diseases, including migraine, headache, and pain.

OBJECTIVE

Review the medical literature for the use of cannabis/cannabinoids in the treatment of migraine, headache, facial pain, and other chronic pain syndromes, and for supporting evidence of a potential role in combatting the opioid epidemic. Review the medical literature involving major and minor cannabinoids, primary and secondary terpenes, and flavonoids that underlie the synergistic entourage effects of cannabis. Summarize the individual medicinal benefits of these substances, including analgesic and anti-inflammatory properties.

CONCLUSION

There is accumulating evidence for various therapeutic benefits of cannabis/cannabinoids, especially in the treatment of pain, which may also apply to the treatment of migraine and headache. There is also supporting evidence that cannabis may assist in opioid detoxification and weaning, thus making it a potential weapon in battling the opioid epidemic. Cannabis science is a rapidly evolving medical sector and industry with increasingly regulated production standards. Further research is anticipated to optimize breeding of strain-specific synergistic ratios of cannabinoids, terpenes, and other phytochemicals for predictable user effects, characteristics, and improved symptom and disease-targeted therapies.

The protective and therapeutic effects of linalool against doxorubicin-induced cardiotoxicity in Wistar albino rats

The aim of the present study was to determine the protective and therapeutic effects of linalool (LIN) against doxorubicin (DOX)-induced cardiotoxicity in rats histologically and biochemically. In experiments, 64 male Wistar albino rats were randomly divided into eight groups ( n = 8). These groups were control (C) (0.9% saline solution), DOX (20 mg/kg DOX), LIN50 (50 mg/kg LIN), LIN100 (100 mg/kg LIN), DOX + LIN50 (20 mg/kg DOX and 50 mg/kg LIN), DOX + LIN100 (20 mg/kg DOX and 100 mg/kg LIN), LIN50 + DOX (50 mg/kg LIN and 20 mg/kg DOX), and LIN100 + DOX (100 mg/kg LIN and 20 mg/kg DOX). It was determined that necrosis and extensive inflammatory cell infiltration were observed in the DOX group. It was determined that histopathological changes significantly decreased in groups treated with LIN after DOX administration. While the caspase-3 immunostaining was highly evident in DOX group apoptotic cells ( p < 0.001, for all), the intensity of caspase-3 immunostaining in the treatment groups decreased ( p < 0.05). While DOX administration resulted in a significant increase in malondialdehyde (MDA) levels and plasma Creatine kinase (CK) and lactate dehydrogenase (LDH) levels in cardiac tissue when compared to the C groups, it was observed that DOX + LIN administration led to a significant decrease in MDA, plasma CK and LDH levels and a significant increase in glutathione (GSH), superoxide dismutase, and catalase enzyme levels. Finally, it was concluded that DOX led to heavy cardiotoxicity and DOX + LIN administration could remove cardiomyopathy symptoms.

Getting high with the most high: Entheogens in the Old Testament

This article collects evidence from psychopharmacology, scripture, and archeology to explore several preparations for consumption described in the Old Testament: Manna, Showbread, the Holy Ointment, and the Tabernacle Incense. The Ointment and the Incense are herbal preparations used by the priestly caste to facilitate a direct experience of the Israelite God. A wide variety of psychoactive components are found in these preparations, including GABA-receptor agonists and modulators, opioid receptor agonists, and other agents. They are normally broken down by the body’s enzymes, and therefore orally inactive, but the Holy Ointment also contains inhibitors specific to the enzymes in question. The preparations indicate that the ancient Israelites had a profound understanding of synergism, and the way they are consumed and the taboos around them are highly suggestive of their use as psychoactive agents.

Cannabis and the Anxiety of Fragmentation-A Systems Approach for Finding an Anxiolytic Cannabis Chemotype

Cannabis sativa is a medicinal herb with a diverse range of chemotypes that can exert both anxiolytic and anxiogenic effects on humans. Medical cannabis patients receiving organically grown cannabis from a single source were surveyed about the effectiveness of cannabis for treating anxiety. Patients rated cannabis as highly effective overall for treating anxiety with an average score of 8.03 on a Likert scale of 0 to 10 (0 = not effective, 10 = extremely effective). Patients also identified which strains they found the most or least effective for relieving their symptoms of anxiety. To find correlations between anxiolytic activity and chemotype, the top four strains voted most and least effective were analyzed by HPLC-MS/MS to quantify cannabinoids and GC-MS to quantify terpenes. Tetrahydrocannabinol (THC) and trans-nerolidol have statistically significant correlations with increased anxiolytic activity. Guiaol, eucalyptol, γ-terpinene, α-phellandrene, 3-carene, and sabinene hydrate all have significant correlations with decreased anxiolytic activity. Further studies are needed to better elucidate the entourage effects that contribute to the anxiolytic properties of cannabis varieties.

Linalool Ameliorates Memory Loss and Behavioral Impairment Induced by REM-Sleep Deprivation through the Serotonergic Pathway

Rapid eye movement (REM) sleep has an essential role in the process of learning and memory in the hippocampus. It has been reported that linalool, a major component of Lavandula angustifolia, has antioxidant, anti-inflammatory, and neuroprotective effects, along with other effects. However, the effect of linalool on the cognitive impairment and behavioral alterations that are induced by REM-sleep deprivation has not yet been elucidated. Several studies have reported that REM-sleep deprivation-induced memory deficits provide a well-known model of behavioral alterations. In the present study, we examined whether linalool elicited an anti-stress effect, reversing the behavioral alterations observed following REM-sleep deprivation in mice. Furthermore, we investigated the underlying mechanism of the effect of linalool. Spatial memory and learning memory were assessed through Y maze and passive avoidance tests, respectively, and the forced swimming test was used to evaluate anti-stress activity. The mechanisms through which linalool improves memory loss and behavioral alterations in sleep-deprived mice appeared to be through an increase in the serotonin levels. Linalool significantly ameliorated the spatial and learning memory deficits, and stress activity observed in sleep-deprived animals. Moreover, linalool led to serotonin release, and cortisol level reduction. Our findings suggest that linalool has beneficial effects on the memory loss and behavioral alterations induced by REM-sleep deprivation through the regulation of serotonin levels.

Patterns of medicinal cannabis use, strain analysis, and substitution effect among patients with migraine, headache, arthritis, and chronic pain in a medicinal cannabis cohort

BACKGROUND

Medicinal cannabis registries typically report pain as the most common reason for use. It would be clinically useful to identify patterns of cannabis treatment in migraine and headache, as compared to arthritis and chronic pain, and to analyze preferred cannabis strains, biochemical profiles, and prescription medication substitutions with cannabis.

METHODS

Via electronic survey in medicinal cannabis patients with headache, arthritis, and chronic pain, demographics and patterns of cannabis use including methods, frequency, quantity, preferred strains, cannabinoid and terpene profiles, and prescription substitutions were recorded. Cannabis use for migraine among headache patients was assessed via the ID Migraine™ questionnaire, a validated screen used to predict the probability of migraine.

RESULTS

Of 2032 patients, 21 illnesses were treated with cannabis. Pain syndromes accounted for 42.4% (n = 861) overall; chronic pain 29.4% (n = 598;), arthritis 9.3% (n = 188), and headache 3.7% (n = 75;). Across all 21 illnesses, headache was a symptom treated with cannabis in 24.9% (n = 505). These patients were given the ID Migraine™ questionnaire, with 68% (n = 343) giving 3 "Yes" responses, 20% (n = 102) giving 2 "Yes" responses (97% and 93% probability of migraine, respectively). Therefore, 88% (n = 445) of headache patients were treating probable migraine with cannabis. Hybrid strains were most preferred across all pain subtypes, with "OG Shark" the most preferred strain in the ID Migraine™ and headache groups. Many pain patients substituted prescription medications with cannabis (41.2-59.5%), most commonly opiates/opioids (40.5-72.8%). Prescription substitution in headache patients included opiates/opioids (43.4%), anti-depressant/anti-anxiety (39%), NSAIDs (21%), triptans (8.1%), anti-convulsants (7.7%), muscle relaxers (7%), ergots (0.4%).

CONCLUSIONS

Chronic pain was the most common reason for cannabis use, consistent with most registries. The majority of headache patients treating with cannabis were positive for migraine. Hybrid strains were preferred in ID Migraine™, headache, and most pain groups, with "OG Shark", a high THC (Δ9-tetrahydrocannabinol)/THCA (tetrahydrocannabinolic acid), low CBD (cannabidiol)/CBDA (cannabidiolic acid), strain with predominant terpenes β-caryophyllene and β-myrcene, most preferred in the headache and ID Migraine™ groups. This could reflect the potent analgesic, anti-inflammatory, and anti-emetic properties of THC, with anti-inflammatory and analgesic properties of β-caryophyllene and β-myrcene. Opiates/opioids were most commonly substituted with cannabis. Prospective studies are needed, but results may provide early insight into optimizing crossbred cannabis strains, synergistic biochemical profiles, dosing, and patterns of use in the treatment of headache, migraine, and chronic pain syndromes.

The effects of herbal medicine on epilepsy

Traditional herbal medicine plays a significant role in the treatment of epilepsy. Though herbal medicine is widely used in antiepileptic treatment, there is a lack of robust evidence for efficacy and toxicity of most herbs. Besides, the herbal medicine should be subject to evidence-based scrutiny. In this context, we present a review to introduce the effects of herbal medicine on epilepsy. However, hundreds of herbal medicines have been investigated in the available studies. Some commonly used herbal medicines for epilepsy have been listed in our study. The overwhelming majority of these data are based on animal experiments. The lack of clinical data places constraints on the clinical recommendation of herbal medicine. Our study may conduct further studies and provide some insight on the development of anti-epileptic drugs.

Coriander (Coriandrum sativum): A promising functional food toward the well-being

Coriandrum sativum (C. sativum) or coriander is one of the most popularly used spices in culinary worldwide, and its medicinal values has been recognized since ancient time. C. sativum contains bioactive phytochemicals that are accounted for a wide range of biological activities including antioxidant, anticancer, neuroprotective, anxiolytic, anticonvulsant, analgesic, migraine-relieving, hypolipidemic, hypoglycemic, hypotensive, antimicrobial, and antiinflammatory activities. The major compound, linalool, abundantly found in seeds is remarked for its abilities to modulate many key pathogenesis pathways of diseases. Apart from the modulating effects, the potent antioxidant property of the C. sativum provides a key mechanism behind its protective effects against neurodegenerative diseases, cancer, and metabolic syndrome. This review shed light on comprehensive aspects regarding the therapeutic values of the C. sativum, which indicate its significance of being a promising functional food for promoting the well-being in the era of aging and lifestyle-related diseases.

Effect of the Leaf Essential Oil from Cinnamosma madagascariensis Danguy on Pentylenetetrazol-induced Seizure in Rats

In the Malagasy traditional practices, the smoke from burning leaves of Cinnamosma madagascariensis Danguy is inhaled to treat brain disorders such as dementia, epilepsy, and headache. In the present work, we have evaluated the in vivo anticonvulsant effects of the essential oil from leaves of C. madagascariensis (CMEO). CMEO was isolated by steam distillation. The anticonvulsant activity of CMEO (0.4 and 0.8 ml/kg bw) administered subcutaneously was evaluated on pentylenetetrazol (PTZ)-induced seizures in Wistar rats; diazepam was used as positive control. Linalool, limonene, and myrcene were the major CMEO constituents. At the dose of 0.8 ml/kg, CMEO completely arrested the PTZ-induced convulsions with moderate sedative effects. The traditional anticonvulsant use of C. madagascariensis was confirmed allowing us to candidate molecules from CMEO as potential drugs to treat convulsions associated with strong agitation.

Neurotoxicity of fragrance compounds: A review

Fragrance compounds are chemicals belonging to one of several families, which are used frequently and globally in cosmetics, household products, foods and beverages. A complete list of such compounds is rarely found on the ingredients-list of such products, as "fragrance mixtures" are defined as "trade secrets" and thus protected by law. While some information regarding the general toxicity of some of these compounds is available, their neurotoxicity is known to a lesser extent. Here, we discuss the prevalence and neurotoxicity of fragrance compounds belonging to the three most common groups: phthalates, synthetic musks and chemical sensitizers.

Cannabis Pharmacology: The Usual Suspects and a Few Promising Leads

The golden age of cannabis pharmacology began in the 1960s as Raphael Mechoulam and his colleagues in Israel isolated and synthesized cannabidiol, tetrahydrocannabinol, and other phytocannabinoids. Initially, THC garnered most research interest with sporadic attention to cannabidiol, which has only rekindled in the last 15 years through a demonstration of its remarkably versatile pharmacology and synergy with THC. Gradually a cognizance of the potential of other phytocannabinoids has developed. Contemporaneous assessment of cannabis pharmacology must be even far more inclusive. Medical and recreational consumers alike have long believed in unique attributes of certain cannabis chemovars despite their similarity in cannabinoid profiles. This has focused additional research on the pharmacological contributions of mono- and sesquiterpenoids to the effects of cannabis flower preparations. Investigation reveals these aromatic compounds to contribute modulatory and therapeutic roles in the cannabis entourage far beyond expectations considering their modest concentrations in the plant. Synergistic relationships of the terpenoids to cannabinoids will be highlighted and include many complementary roles to boost therapeutic efficacy in treatment of pain, psychiatric disorders, cancer, and numerous other areas. Additional parts of the cannabis plant provide a wide and distinct variety of other compounds of pharmacological interest, including the triterpenoid friedelin from the roots, canniprene from the fan leaves, cannabisin from seed coats, and cannflavin A from seed sprouts. This chapter will explore the unique attributes of these agents and demonstrate how cannabis may yet fulfil its potential as Mechoulam's professed "pharmacological treasure trove."

Phytomedical assessment of two Cymbopogon species found in Nkonkobe Municipality: toxicological effect on human Chang liver cell line

Background

Cymbopogon species are widely used as herbal remedies by the traditional healers living in Nkonkobe Municipality for the treatment and management of skin and respiratory infections. According to our survey, the plants seem to be very important because of the higher demands.

Methods

The leaves of C. validis and C. plurinodis were hydro-distilled and the resulted extracted oils were analyzed by GC/MS. Minimum inhibitory concentrations (MICs) ranging from 7.8 to 500.0 μg/ml of the extracted oils were tested against eight bacterial strains, using micro-well dilution method. The human Chang liver cell viability was determined using the CellTiter-Blue cell assay.

Results

GC-MS analysis of the C. validis essential oil amounted to 87.03%, major components identified were Linalyl alcohol (18.9%), 2-Nephthalenemethanol (6.67%), Longifolene (6.53%), Cubedol (6.08%). Total oil percentage of C. plurinodis was 81.47% and the main components were characterized as 3-Cyclohexane-1-ol (13.58%), Nerolidol (13.6%) and 2-Carene (12.6%). The essential oils from both plants were found to be active against the growth of Gram positive than the Gram negative bacterial tested. Lethal dose at 50 (LD₅₀) of both plants showed 74.87 ± 1.41 and 81.66 ± 1.40 degree of toxicity at 24 h.

Conclusion

Both plants extracts were toxic to human Chang liver cell lines.

Exploring Pharmacological Mechanisms of Lavender (Lavandula angustifolia) Essential Oil on Central Nervous System Targets

Lavender essential oil is traditionally used and approved by the European Medicines Agency (EMA) as herbal medicine to relieve stress and anxiety. Some animal and clinical studies reveal positive results in models of anxiety and depression although very little research has been done on molecular mechanisms. Our work consisted of evaluating the effects of lavender (Lavandula angustifolia) essential oil on central nervous system well-established targets, such as MAO-A, SERT, GABA_Aand NMDA receptors as well as in vitro models of neurotoxicity. The results showed that lavender essential oil and its main components exert affinity for the glutamate NMDA-receptor in a dose-dependent manner with an IC₅₀ value of 0.04 μl/mL for lavender oil. In addition, lavender and linalool were also able to bind the serotonin transporter (SERT) whereas they did not show affinity for GABA_A-benzodiazepine receptor. In three different models of neurotoxicity, lavender did not enhance the neurotoxic insult and improved viability of SH-SY5Y cells treated with hydrogen peroxide. According to our data, the anxiolytic and antidepressant-like effects attributed to lavender may be due to an antagonism on the NMDA-receptor and inhibition of SERT. This study suggests that lavender essential oil may exert pharmacological properties via modulating the NMDA receptor, the SERT as well as neurotoxicity induced by hydrogen peroxide.

Protective effects of linalool against amyloid beta-induced cognitive deficits and damages in mice

AIM

Amyloid-beta (Aβ)-mediated neurotoxicity plays a pivotal role in the pathogenesis of Alzheimer's disease (AD), which induces oxidative stress and apoptosis. Linalool (LI) is a volatile monoterpene showing positive effect in AD treatment. This study was designed to research the protective effect of LI against neurotoxicity and cognitive deficits induced by Aβ_1-40 in mice.

MAIN METHODS

Aβ_1-40 (4μg) solution was injected in the bilateral hippocampus to induce cognitive deficits of mice. The protective effects of LI were evaluated by behavioral tests and the related mechanism was further explored by observing the apoptosis and oxidative stress changes in the hippocampus of mice.

KEY FINDINGS

LI (100mg/kg, i.p.) administration significantly improved the cognitive performance of model mice in Morris water maze test and step-through test. Meanwhile, LI effectively reversed the Aβ_1-40 induced hippocampal cell injury in histological examination, apoptosis in TUNEL assay, changes of oxidative stress indicators (SOD, GPX, AChE). Besides, the activated cleaved caspase (caspase-3, caspase-9) was suppressed and Nrf2, HO-1 expression was elevated by LI treatment.

SIGNIFICANCE

LI could attenuate cognitive deficits induced by Aβ, and the neuroprotective effect of LI might be mediated by alleviation of apoptosis, oxidative stress depending on activation of Nrf2/HO-1 signaling. We could assume that LI has the potential to be a neuroprotective substance for AD therapy.

Essential Oil of Ocimum basilicum L. and (-)-Linalool Blocks the Excitability of Rat Sciatic Nerve

The racemate linalool and its levogyrus enantiomer [(−)-LIN] are present in many essential oils and possess several pharmacological activities, such as antinociceptive and anti-inflammatory. In this work, the effects of essential oil obtained from the cultivation of the Ocimum basilicum L. (EOOb) derived from Germplasm Bank rich in (−)-LIN content in the excitability of peripheral nervous system were studied. We used rat sciatic nerve to investigate the EOOb and (−)-LIN effects on neuron excitability and the extracellular recording technique was used to register the compound action potential (CAP). EOOb and (−)-LIN blocked the CAP in a concentration-dependent way and these effects were reversible after washout. EOOb blocked positive amplitude of 1st and 2nd CAP components with IC₅₀ of 0.38 ± 0.2 and 0.17 ± 0.0 mg/mL, respectively. For (−)-LIN, these values were 0.23 ± 0.0 and 0.13 ± 0.0 mg/mL. Both components reduced the conduction velocity of CAP and the 2nd component seems to be more affected than the 1st component. In conclusion EOOb and (−)-LIN inhibited the excitability of peripheral nervous system in a similar way and potency, revealing that the effects of EOOb on excitability are due to the presence of (−)-LIN in the essential oil.

Linalool reverses neuropathological and behavioral impairments in old triple transgenic Alzheimer's mice

Alzheimer's disease (AD) is an age-related progressive neurodegenerative disorder. Several types of treatments have been tested to block or delay the onset of the disease, but none have been completely successful. Diet, lifestyle and natural products are currently the main scientific focuses. Here, we evaluate the effects of oral administration of the monoterpene linalool (25 mg/kg), every 48 h for 3 months, on aged (21-24 months old) mice with a triple transgenic model of AD (3xTg-AD) mice. Linalool-treated 3xTg-AD mice showed improved learning and spatial memory and greater risk assessment behavior during the elevated plus maze. Hippocampi and amygdalae from linalool-treated 3xTg-AD mice exhibited a significant reduction in extracellular β-amyloidosis, tauopathy, astrogliosis and microgliosis as well as a significant reduction in the levels of the pro-inflammatory markers p38 MAPK, NOS2, COX2 and IL-1β. Together, our findings suggest that linalool reverses the histopathological hallmarks of AD and restores cognitive and emotional functions via an anti-inflammatory effect. Thus, linalool may be an AD prevention candidate for preclinical studies.

Neuroprotective effects of (-)-linalool against oxygen-glucose deprivation-induced neuronal injury

(-)-Linalool, a major component of many essential oils, is widely used in cosmetics and flavoring ingredients as well as in traditional medicines. Although various in vitro and in vivo studies have shown that (-)-linalool has anti-convulsant, anti-nociceptive, anti-inflammatory and anti-oxidative properties, its anti-ischemic/hypoxic effects have yet to be determined. This study assessed the neuroprotective effects of (-)-linalool against oxygen-glucose deprivation/reoxygenation (OGD/R)-induced cortical neuronal injury, an in vitro model of ischemic stroke. (-)-Linalool significantly attenuated OGD/R-evoked cortical neuronal injury/death, although it did not inhibit N-methyl-D-aspartate (NMDA)-induced excitotoxicity. (-)-Linalool significantly reduced intracellular oxidative stress during OGD/R-induced injury, as well as scavenging peroxyl radicals (Trolox equivalents or TE = 3.8). This anti-oxidant effect was found to correlate with the restoration of OGD/R-induced decreases in the activities of SOD and catalase. In addition, (-)-linalool inhibited microglial migration induced by monocyte-chemoattractant protein-1 (MCP-1), a chemokine released by OGD/R. These findings show that (-)-linalool has neuroprotective effects against OGD/R-induced neuronal injury, which may be due to its anti-oxidant and anti-inflammatory activities. Detailed examination of the anti-ischemic mechanisms of (-)-linalool may indicate strategies for the development of drugs to treat cerebral ischemic injury.

Lavender oil suppresses indoleamine 2,3-dioxygenase activity in human PBMC

BACKGROUND

Lavender remedies have been used in traditional medicine because of antimicrobial, anti-inflammatory and mood alleviating effects, but underlying molecular mechanisms are not yet fully elucidated. Recently, studies investigating the effects of lavender oil in the context of psychiatric disorders have indicated potent pharmacological properties. Metabolism of tryptophan by indoleamine 2,3-dioxygenase (IDO) was found to provide a biochemical link between immunology and neuroendocrinology and to be a frequent target of natural products.

METHODS

In this in vitro study, interferences of lavender oil and constituents (-)-linalool, (+)-α-pinene and (+)-limonene with tryptophan catabolism by IDO and formation of neopterin via guanosine triphosphate (GTP)-cyclohydrolase-I and of interferon-γ have been investigated using unstimulated and phytohemagglutinin (PHA)-stimulated human peripheral blood mononuclear cells (PBMC).

RESULTS

Treatment with lavender oil dose-dependently suppressed PHA-induced tryptophan breakdown and kynurenine formation. Similar effects were observed for the three constituents. In parallel, formation of neopterin and interferon-γ was diminished upon lavender oil treatment. In unstimulated PBMC, effect of lavender oil treatment was similar, but less pronounced.

CONCLUSION

Data from this in vitro study suggest that lavender oil treatment might contribute to the modulation of the immune and neuroendocrine system by interfering with activation-induced tryptophan breakdown and IDO activity.

Biotransformation of monoterpenoids and their antimicrobial activities

Biotransformation is an economically and ecologically viable technology which has been used extensively to modify the structures of many classes of biologically active products. The discovery of novel antimicrobial metabolites from biotransformation is an important alternative to overcome the increasing levels of drug resistance by plant and human pathogens. Monoterpenes, the main constituents of essential oils, are known for their antimicrobial activities. In 2004, Farooq, Atta-Ur-Rahman and Choudhary published a review on fungal transformation of monoterpenes which covers papers published up to 2002. The present review not only updates the previous one but also discusses the antimicrobial activities (antibacterial, antifungal and antiviral) of biotransformed compounds.

Linalool and linalool complexed in β-cyclodextrin produce anti-hyperalgesic activity and increase Fos protein expression in animal model for fibromyalgia

The analgesic activity of (-)-linalool (LIN), a monoterpene present in essential oils of Lamiaceae species, has been previously demonstrated in rodents. However, its possible use in the treatment of fibromyalgia (FM) was never demonstrated. Additionally, as a short half-life is a limitation for the LIN medicinal application, the employment of drug delivery systems has been used to improve pharmaceutical properties of this compound. We investigated the anti-nociceptive effect of LIN, isolated or in β-cyclodextrin complex (LIN-CD), in an animal model of chronic non-inflammatory muscle pain (a FM animal model), as well as its effect on the central nervous system (CNS). Male Swiss mice were subjected to two injections of acidic saline (pH 4; 20 μL/gastrocnemius) and were treated on alternate days, with LIN-CD (25 mg/kg, p.o.), LIN (25 mg/kg, p.o.), tramadol (TRM 4 mg/kg, i.p.), or vehicle (neutral saline). After 60 min, they were screened for mechanical hyperalgesia (von Frey), motor coordination (rotarod), and muscle strength (grip strength meter) for 27 days. The CNS areas involved in the anti-hyperalgesic activity were evaluated by immunofluorescence. LIN or LIN-CD produced a significant reduction (p < 0.001) of mechanical hyperalgesia on chronic non-inflammatory muscle pain model, which remained for 24 h only in LIN-CD, and these compounds significantly (p < 0.05) activated neurons of the locus coeruleus, nucleus raphe magnus, and periaqueductal gray areas. So, our results suggest that LIN-CD improved analgesic profile of LIN, with a probable involvement of descending pain pathways and the anti-nociceptive effect of linalool in an animal model of chronic non-inflammatory muscle pain. So far, only the investigations in animal models of inflammatory pain and supraspinatus were published.

Antidepressant activity of Litsea glaucescens essential oil: identification of β-pinene and linalool as active principles

ETHNOPHARMACOLOGICAL RELEVANCE

Litsea glaucescens (Lauraceae) has been used in Mexican Traditional Medicine to relieve illness related to central nervous system, such as epilepsy, fright and sadness. In this study, L. glaucescens essential oil properties on central nervous system were evaluated in mice using different behavioral tests.

MATERIALS AND METHODS

The essential oil was obtained by hydrodistillation and analyzed by GC/MS. Identification of major compounds was also carried out by comparison with authentic samples. The psychopharmacological profile of L. glaucescens essential oil, and some its major compounds, were evaluated in mice using several experimental models: forced swimming test (FST: Antidepressant-like activity), open field test (OFT: Spontaneous locomotor activity), elevated plus-maze (EPM: Anxiolytic-like activity), exploratory cylinder (ECT: Sedative-like activity), rotarod (motor coordination) and traction performance (myo-relaxant effect) the essential oil and active principles was administered intraperitoneally.

RESULTS

The essential oil showed antidepressant-like activity at doses of 100 and 300 mg/Kg. The monoterpenes β-pinene and linalool were identified as the two main active principles of the essential oil, and showed antidepressant-like and sedative-like activity. Eucalyptol, limonene and α-pinene they did not show antidepressant-like activity, and were not further tested.

CONCLUSIONS

L. glaucescens essential oil showed antidepressant activity, β-pinene and linalool were identified as its active principles. These results support the use of L. glaucescens in Mexican Traditional Medicine for the treatment of sadness.