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

The genus Litsea: A comprehensive review of traditional uses, phytochemistry, pharmacological activities and other studies

ETHNOPHARMACOLOGICAL RELEVANCE

The genus L. has high medicinal value and has traditional been used to treat a variety of gastrointestinal disorders, as well as diabetes, edema, colds, arthritis, asthma, and traumatic injuries.

AIM OF THE REVIEW

This work addresses the missing information by conducting a comprehensive analysis of the traditional uses, chemical components, and pharmacological applications of the more reported species of the genus L. The origin of the genus, its toxicology, and the use of classical therapies in modern medicine were also discussed. It provides references for historical evidence, resource development, and medical research on the genus.

METHOD

ology: Data about the genus L. were gathered via Web of Science, PubMed, Science Direct, Google Scholar, Connected Papers, China National Knowledge Infrastructure (CNKI), electronic ancient books and local chronicles. The WFO Plant List (wfoplantlist.org) and Flora of China (www.iplant.cn) confirmed L.'s Latin name, and the species information. The program ChemBioDraw Ultra 14.0 was used to create the molecular structures of the compounds that were displayed in the text.

RESULT

Currently, at least 740 constituents have been isolated and identified from L. These include 9 groups of chemicals, such as flavonoids, alkaloids, and terpenoids. They have been shown to have over 20 biological properties in vivo and in vitro, such as antibacterial, anti-inflammatory, and anti-oxidant effects.

CONCLUSION

Based on pharmacological investigations, chemical components, and traditional folk applications, L. is considered a medicinal plant having a variety of pharmacological actions. However, although the pharmacological activity of the L. genus has been preliminary demonstrated, most have only been assessed using simple in vitro cell lines or animal disease models. In order to fully elucidate the pharmacological activity and mechanisms of L., future studies should be conducted in a more comprehensive clinical manner.

FhMYB108 Regulates the Expression of Linalool Synthase Gene in Freesia hybrida and Arabidopsis

Acting as the most abundant and widely distributed volatile secondary metabolites in plants, terpenoids play crucial roles in diverse physiological regulations and metabolic processes. Terpene synthases play a decisive role in determining the composition and diversity of terpenoids. Though the regulation of terpene synthases has been extensively investigated across various plant species, limited studies have focused on the upstream transcriptional regulation of terpene synthases. In this study, we have identified linalool as the predominant volatile compound that is released gradually from Freesia hybrida flowers throughout flower blooming. In the context of the transcriptome, a typical MYB transcription factor, FhMYB108, was screened based on homologous gene comparison. FhMYB108 is capable of regulating the expression of FhTPS1, and both their expression levels showed gradual increase during flower opening. Moreover, FhMYB108 exerts a stimulatory effect on the transcription of Arabidopsis thaliana AtTPS14, while no significant increase in AtTPS14 expression is observed upon the stabilization of FhMYB108 in A. thaliana. The highly expressed AtMYC2 in A. thaliana could interact with FhMYB108 to suppress the activation of AtTPS14 by FhMYB108. The present study not only elucidates the regulatory mechanism underlying linalool synthesis but also discovers the synergistic effect of MYB and bHLH transcription factors in governing the biosynthesis of volatile terpenoids.

The Analgesic Potential of Litsea Species: A Systematic Review

Various plant species from the Litsea genus have been claimed to be beneficial for pain relief. The PRISMA approach was adopted to identify studies that reported analgesic properties of plants from the Litsea genus. Out of 450 records returned, 19 primary studies revealed the analgesic potential of nine Litsea species including (1) Litsea cubeba, (2) Litsea elliptibacea, (3) Litsea japonica, (4) Litsea glutinosa, (5) Litsea glaucescens, (6) Litsea guatemalensis, (7) Litsea lancifolia, (8) Litsea liyuyingi and (9) Litsea monopetala. Six of the species, 1, 3, 4, 7, 8 and 9, demonstrated peripheral antinociceptive properties as they inhibited acetic-acid-induced writhing in animal models. Species 1, 3, 4, 8 and 9 further showed effects via the central analgesic route at the spinal level by increasing the latencies of heat stimulated-nocifensive responses in the tail flick assay. The hot plate assay also revealed the efficacies of 4 and 9 at the supraspinal level. Species 6 was reported to ameliorate hyperalgesia induced via partial sciatic nerve ligation (PSNL). The antinociceptive effects of 1 and 3 were attributed to the regulatory effects of their bioactive compounds on inflammatory mediators. As for 2 and 5, their analgesic effect may be a result of their activity with the 5-hydroxytryptamine 1A receptor (5-HT1AR) which disrupted the pain-stimulating actions of 5-HT. Antinociceptive activities were documented for various major compounds of the Litsea plants. Overall, the findings suggested Litsea species as good sources of antinociceptive compounds that can be further developed to complement or substitute prescription drugs for pain management.

Cannabinoid treatments in epilepsy and seizure disorders

Cannabis has been used to treat convulsions and other disorders since ancient times. In the last few decades, preclinical animal studies and clinical investigations have established the role of cannabidiol (CBD) in treating epilepsy and seizures and support potential therapeutic benefits for cannabinoids in other neurological and psychiatric disorders. Here, we comprehensively review the role of cannabinoids in epilepsy. We briefly review the diverse physiological processes mediating the central nervous system response to cannabinoids, including Δ9-tetrahydrocannabinol (Δ9-THC), cannabidiol, and terpenes. Next, we characterize the anti- and proconvulsive effects of cannabinoids from animal studies of acute seizures and chronic epileptogenesis. We then review the clinical literature on using cannabinoids to treat epilepsy, including anecdotal evidence and case studies as well as the more recent randomized controlled clinical trials that led to US Food and Drug Administration approval of CBD for some types of epilepsy. Overall, we seek to evaluate our current understanding of cannabinoids in epilepsy and focus future research on unanswered questions.

Inhaled Litsea glaucescens K. (Lauraceae) leaves' essential oil has anxiolytic and antidepressant-like activity in mice by BDNF pathway activation

ETHNOPHARMACOLOGICAL RELEVANCE

Litsea glaucescens K. (Lauraceae) is a small tree from the Mexican and Central American temperate forests, named as "Laurel". Its aromatic leaves are ordinarily consumed as condiments, but also are important in Mexican Traditional Medicine, and among the most important non wood forest products in this area. The leaves are currently used in a decoction for the relief of sadness by the Mazahua ethnic group. Interestingly, "Laurel" has a long history. It was named as "Ehecapahtli" (wind medicine) in pre-Columbian times and applied to heal maladies correlated to the Central Nervous System, among them depression, according to botanical texts written in the American Continent almost five centuries ago.

AIM OF THE STUDY

Depression is the first cause of incapacity in the world, and society demands alternative treatments, including aromatherapy. We have previously demonstrated the antidepressant-like activity of L. glaucescens leaves' essential oil (LEO), as well as their monoterpenes linalool, and beta-pinene by intraperitoneal route in a mice behavioral model. Here we now examined if LEO and linalool exhibit this property and anxiolytic activity when administered to mice by inhalation. We also investigated if these effects occur by BDNF pathway activation in the brain.

MATERIALS AND METHODS

The LEO was prepared by distillation with water steam and analyzed by gas chromatography-mass spectrometry (GC-MS). The monoterpenes linalool, eucalyptol and β-pinene were identified and quantified. Antidepressant type properties were determined with the Forced Swim Test (FST) on mice previously exposed to LEO or linalool in an inhalation chamber. The spontaneous locomotor activity and the sedative effect were assessed with the Open Field Test (OFT), and the Exploratory Cylinder (EC), respectively. The anxiolytic properties were investigated with the Elevated Plus Maze Apparatus (EPM) and the Hole Board Test (HBT). All experiments were video documented. The mice were subjected to euthanasia, and the brain hippocampus and prefrontal cortex were dissected.

RESULTS

The L. glaucescens essential oil (LEO) contains 31 compounds according to GC/MS, including eucalyptol, linalool and beta-pinene. The LEO has anxiolytic effect by inhalation in mice, as well as linalool, and β-pinene, as indicated by OFT and EC tests. The LEO and imipramine have antidepressant like activity in mice as revealed by the FST; however, linalool and ketamine treatments didn't modify the time of immobility. The BDNF was increased in FST in mice treated with LEO in both areas of the brain as revealed by Western blot; but did not decrease the level of corticosterone in plasma. The OFT indicated that LEO and imipramine didn't reduce the spontaneous motor activity, while linalool and ketamine caused a significant decrease.

CONCLUSION

Here we report by the first time that L. glaucescens leaves essential oil has anxiolytic effect by inhalation in mice, as well as linalool, and β-pinene. This oil also maintains its antidepressant-like activity by this administration way, similarly to the previously determined intraperitoneally. Since inhalation is a common administration route for humans, our results suggest L. glaucescens essential oil deserve future investigation due to its potential application in aromatherapy.

Linalool, a Fragrance Compound in Plants, Protects Dopaminergic Neurons and Improves Motor Function and Skeletal Muscle Strength in Experimental Models of Parkinson's Disease

Parkinson's disease (PD) is a common neurodegenerative disorder characterized by the gradual loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc), resulting in reduced dopamine levels in the striatum and eventual onset of motor symptoms. Linalool (3,7-dimethyl-1,6-octadien-3-ol) is a monoterpene in aromatic plants exhibiting antioxidant, antidepressant, and anti-anxiety properties. The objective of this study is to evaluate the neuroprotective impacts of linalool on dopaminergic SH-SY5Y cells, primary mesencephalic and cortical neurons treated with 1-methyl-4-phenylpyridinium ion (MPP+), as well as in PD-like mice induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Cell viability, α-tubulin staining, western blotting, immunohistochemistry and behavioral experiments were performed. In MPP+-treated SH-SY5Y cells, linalool increased cell viability, reduced neurite retraction, enhanced antioxidant defense by downregulation of apoptosis signaling (B-cell lymphoma 2 (Bcl-2), cleaved caspase-3 and poly ADP-ribose polymerase (PARP)) and phagocyte NADPH oxidase (gp91phox), as well as upregulation of neurotrophic signaling (brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF)) and nuclear factor-erythroid 2 related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) pathway. In MPP+-treated primary mesencephalic neurons, linalool enhanced the expressions of tyrosine hydroxylase (TH), Sirtuin 1 (SirT1), and parkin. In MPP+-treated primary cortical neurons, linalool upregulated protein expression of SirT1, γ-Aminobutyric acid type A-α1 (GABAA-α1), and γ-Aminobutyric acid type B (GABAB). In PD-like mice, linalool attenuated the loss of dopamine neurons in SNpc. Linalool improved the motor and nonmotor behavioral deficits and muscle strength of PD-like mice. These findings suggest that linalool potentially protects dopaminergic neurons and improves the impairment symptoms of PD.

"Delaying Rot Emergence in Persian Lime (Citrus×latifolia) Through Antifungal Hybrid Films Containing Litsea glaucescens Essential Oil"

Herein we describe the in situ inhibitory activity of three hybrid films (FL1, FL2, and FL3) against two wild strains of Colletotrichum gloeosporioides and Penicillium digitatum as causal agents of rot in Persian limes. The films FL2 and FL3 contained 1.0 and 1.3 % weight/volume Litsea glaucescens essential oil (LgEO) and significantly (p<0.05) delayed rot emergence in Persian limes caused by both pathogens up to 10 days. The physicochemical properties of LgEO and hybrid films were obtained, whereas detailed HPLC profiling revealed that fruit covered with these films significantly (p<0.01) preserved reducing sugars (sucrose, fructose, and glucose), organic acids (citric acid, ascorbic acid, malic acid, and oxalic acid), and flavonoids with nutraceutical activity (hesperidin, eriocitrin, naruritin, neohesperidin, diosmin, vitexin, rutin, and quercetin). This evidence sustains that the composites generated in this investigation improve the shelf life of Persian limes and conserve their nutraceutical content.

Litsea glaucescens Kuth possesses bactericidal activity against Listeria monocytogenes

Background

Litsea glaucencens Kuth is an aromatic plant used for food seasoning food and in Mexican traditional medicine. Among, L. glaucencens leaves properties, it has proven antibacterial activity which can be used against opportunistic pathogens like Listeria monocytogenes, a foodborne bacteria that is the causal agent of listeriosis, a disease that can be fatal in susceptible individuals. The aim of this work was to investigate the antibacterial activity of L. glaucescens Kuth leaf extracts against L. monocytogenes and to identify its bioactive components.

Material and Methods

L. glaucences leaves were macerated with four solvents of different polarity (n-hexane, dichloromethane, ethyl acetate, and methanol). To determine the capacity to inhibit bacterial proliferation in vitro, agar diffusion and microdilution methods were used. Next, we determined the minimal bactericidal concentration (MBC). Finally, we determined the ratio of MBC/MIC. Metabolites present in the active methanolic extract from L. glaucescens Kuth (LgMeOH) were purified by normal-phase open column chromatography. The structure of the antibacterial metabolite was determined using nuclear magnetic resonance (1H, 13C, COSY, HSQC) and by comparison with known compounds.

Results

The LgMeOH extract was used to purify the compound responsible for the observed antimicrobial activity. This compound was identified as 5,7-dihydroxyflavanone (pinocembrin) by analysis of its spectroscopic data and comparison with those described. The MIC and MBC values obtained for pinocembrin were 0.68 mg/mL, and the ratio MBC/MIC for both LgMeOH and pinocembrin was one, which indicates bactericidal activity.

Conclusion

L. glaucences Kuth leaves and its metabolite pinocembrin can be used to treat listeriosis due the bactericidal activity against L. monocytogenes.

Therapeutic Potential of Myrtenal and Its Derivatives-A Review

The investigation of monoterpenes as natural products has gained significant attention in the search for new pharmacological agents due to their ability to exhibit a wide range in biological activities, including antifungal, antibacterial, antioxidant, anticancer, antispasmodic, hypotensive, and vasodilating properties. In vitro and in vivo studies reveal their antidepressant, anxiolytic, and memory-enhancing effects in experimental dementia and Parkinson's disease. Chemical modification of natural substances by conjugation with various synthetic components is a modern method of obtaining new biologically active compounds. The discovery of new potential drugs among monoterpene derivatives is a progressive avenue within experimental pharmacology, offering a promising approach for the therapy of diverse pathological conditions. Biologically active substances such as monoterpenes, for example, borneol, camphor, geraniol, pinene, and thymol, are used to synthesize compounds with analgesic, anti-inflammatory, anticonvulsive, antidepressant, anti-Alzheimer's, antiparkinsonian, antiviral and antibacterial (antituberculosis) properties. Myrtenal is a perspective monoterpenoid with therapeutic potential in various fields of medicine. Its chemical modifications often lead to new or more pronounced biological effects. As an example, the conjugation of myrtenal with the established pharmacophore adamantane enables the augmentation of several of its pivotal properties. Myrtenal-adamantane derivatives exhibited a variety of beneficial characteristics, such as antimicrobial, antifungal, antiviral, anticancer, anxiolytic, and neuroprotective properties, which are worth examining in more detail and at length.

Alpinia oxyphylla Miq. volatile oil ameliorates depressive behaviors and inhibits neuroinflammation in CUMS-exposed mice by inhibiting the TLR4-medicated MyD88/NF-κB signaling pathway

This study aimed to explore the antidepressant effect and underlying mechanism of the Alpinia oxyphylla Miq. volatile oil (AOVO) in mice exposed to chronic unpredictable mild stress (CUMS). C57BL/6 mice were grouped and administered with different dosages of AOVO (0.25, 0.50, 1.00, or 2.00 mL/kg body weight, i.g.), TAK242 (a TLR4 inhibitor, 0.75 mg/kg body weight, i.p.), or TAK242 (0.75 mg/kg body weight, i.p.) + AOVO (0.50 mL/kg body weight, i.g.) for 21 days. Depression-like symptoms in the mice were then evaluated through their body weight gain (BW), the open field test (OFT), the sucrose preference test (SPT), the novelty-suppressed feeding test (NSFT), and forced swimming test (FST). The concentrations of interleukin-1β (IL-1β), interleukin-6 (IL-6), tumor necrosis factor α (TNF-α), and 5-hydroxytyrptamine (5-HT) in the mice were determined using ELISA kits. Hematoxylin and eosin (HE) dying were performed for histopathological examination. The expression of inflammatory proteins was assessed through western blotting (WB) and immunofluorescence staining. AOVO was found to improve the behavioral indexes of CUMS-exposed mice behavioral and synergize TAK242 to mitigate both their depressive symptoms and neuroinflammation. Moreover, AOVO was found to inhibit the hippocampal damage, decrease inflammatory cytokines (Reduced IL-1β, IL-6, and TNF-α by 19.97 %, 22.87 %, and 24.13 %, respectively), and downregulate the expression of TLR4/MyD88/NF-κB signaling pathway-related proteins in the hippocampus of CUMS-exposed mice (Reduced TLR4, MyD88, and NF-κB by 46.14 %, 42.48 %, and 38.08 %, respectively). These findings demonstrate that AOVO can ameliorate depressive behaviors and mitigate neuroinflammation in the CUMS-exposed mice via suppressing the TLR4-medicated MyD88/NF-κB signaling pathway.

Antidepressant Effects of Essential Oils: A Review of the Past Decade (2012-2022) and Molecular Docking Study of Their Major Chemical Components

Depression is a mental disorder that affects more than 300 million people worldwide. The medications available for treatment take a long time to exhibit therapeutic results and present several side effects. Furthermore, there is a decrease in the quality of life of people suffering from this affliction. Essential oils are traditionally used to relieve the symptoms of depression due to the properties of the constituents of these oils to cross the blood-brain barrier acting on depression-related biological receptors associated with reduced toxicity and side effects. In addition, compared to traditional drugs, they have several administration forms. This review provides a comprehensive assessment of studies on plants whose essential oil has exhibit antidepressant activity in the past decade and the mechanism of action of the major components and models tested. An additional in silico study was conducted with the frequent compounds in the composition of these essential oils, providing a molecular approach to the mechanism of action that has been reported in the past decade. This review is valuable for the development of potential antidepressant medications in addition to providing a molecular approach to the antidepressant mechanism of action of the major volatile compounds that have been reported in the past decade.

Five centuries of Cirsium ehrenbergii Sch. Bip. (Asteraceae) in Mexico, from Huitzquilitl to Cardo Santo: History, ethnomedicine, pharmacology and chemistry

ETHNOPHARMACOLOGICAL RELEVANCE

Several medicinal plants, including the endemic herb Cirsum ehrenbergii (Asteraceae), have been documented in manuscripts, medical and botanical books written in Mexico since the XVI century until the present. This unique circumstance is a real window in the time that allows to investigate historical and contemporary ethnopharmacological knowledge.

AIM OF THE STUDY

To examine the persistence, disappearance, and transformation of ethnomedicinal knowledge of C. ehrenbergii along time. Also, to investigate the chemistry and pharmacology of this species in relation to its historical and present day main ethnomedical applications related to Central Nervous System and inflammation.

MATERIALS AND METHODS

A thorough review was performed of written sources of medicinal plants from XVI and onwards. For the pharmacological studies, the organic extracts were tested in mice models to assess its antidepressant and anti-inflammatory properties. The active extracts were studied chemically. The isolated compounds were identified by ¹H, ¹³C NMR, or characterized by GC-MS.

RESULTS

Cirsum ehrenbergii was illustrated for the first time (1552) in the Libellus de Medicinalibus Indorum Herbis (Booklet of Medicinal Plants of the Indians) and named in the Nahuatl native language as huitzquilitl (edible thistle). It was there recommended as nigris sanguinis remedium (remedy for black blood), and for the treatment of illnesses with an inflammatory component. Nigris sanguinis was well known in the European medicine of that time and currently it has been interpreted as "depression". At the present time, peasants and native population in Mexico mainly name C. ehrenbergii in Spanish as cardo Santo (holy thistle). Its original Nahuatl name has been almost forgotten. However, these communities use this species, among other maladies, to heal "nervios" (anxiety and/or depression) and for anti-inflammatory purposes. These ailments and treatments resemble those recorded in the Libellus and in several medicinal plant books along centuries. The ethanol extract of C. ehrenbergii roots showed antidepressant-like activity in mice administered at 300 mg/kg, as indicated by the forced swim test (FST). The glycosylated flavonoid linarin was identified as antidepressant principle and was active at the doses of 30 and 60 mg/kg in the FST. Regarding to anti-inflammatory activity, the most active was the methylene chloride extract of the aerial parts, which contains taraxasterol, pseudotaraxasterol, β-sitosterol and stigmasterol.

CONCLUSIONS

Cirsium ehrenbergii extracts possess antidepressant-like (roots, EtOH) and anti-inflammatory (aerial parts, CH₂Cl₂) properties, containing active compounds. Our results sustain historical and present day ethnomedical applications of this species documented along five centuries.

Beneficial effects of Silexan on co-occurring depressive symptoms in patients with subthreshold anxiety and anxiety disorders: randomized, placebo-controlled trials revisited

Silexan is a proprietary active substance produced from Lavandula angustifolia, with proven anxiolytic efficacy in subthreshold and generalized anxiety disorder as well as in mixed anxiety and depressive disorder with beneficial impact on anxiety-related sleep disturbances. The pharmacological profile and clinical observations suggest that Silexan may also have an antidepressant effect. To investigate the effect of Silexan on co-occurring depressive symptoms, we present a meta-analysis of the five placebo-controlled clinical trials hitherto performed with Silexan in subthreshold anxiety (n = 3) and anxiety disorders (n = 2). Patients of all trials received Silexan 1 × 80 mg/day or placebo for 10 weeks according to random assignment. Assessment of the antidepressant effect was based on item 'depressed mood' from the Hamilton Anxiety Rating Scale (HAMA) administered in all trials and on the total scores of the Montgomery Åsberg Depression Rating Scale (MADRS) or the Hamilton Depression Rating Scale (HAMD) used in three trials. After 10-week treatment, patients receiving Silexan showed significantly more pronounced score reduction for HAMA item 'depressed mood' than those in the placebo group (p = 0.01). Significant superiority of Silexan over placebo could also be shown for mean MADRS or HAMD total score reduction (three studies; p < 0.01). Silexan-treated patients with more severe depressive symptoms at baseline showed more pronounced improvements than those with milder symptoms. Our meta-analysis clearly shows that Silexan has a beneficial effect on co-occurring depressive symptoms in patients with subthreshold anxiety and anxiety disorders and may, hence, lead to important therapeutic implications for depressive disorders.

Linalool attenuated ischemic injury in PC12 cells through inhibition of caspase-3 and caspase-9 during apoptosis

Numerous studies have indicated the pharmacological properties of linalool, a volatile terpene alcohol found in many flowers and spice plants, including anti-nociceptive, anti-inflammatory, and neuroprotective activities. The aim of this study was to explore the mechanisms of neuroprotection provided by (±) linalool and its enantiomer, (R)-(-) linalool against oxygen, and glucose deprivation/reoxygenation (OGD/R) in PC12 cells. PC12 cells were treated with (±) linalool and (R)-(-) linalool before exposure to OGD/R condition. Cell viability, reactive oxygen species (ROS) production, malondialdehyde (MDA) level, DNA damage, and the levels of proteins related to apoptosis were evaluated using MTT, comet assay, and western blot analysis, respectively. IC50 values for the PC12 cells incubated with (±) linalool and (R)-(-) linalool were 2700 and 2600 μM after 14 h, as well as 5440 and 3040 μM after 18 h, respectively. Survival of the ischemic cells pre-incubated with (±) linalool and (R)-(-) linalool (100 μM of both) increased compared to the cells subjected to the OGD/R alone (p < .001). ROS and MDA formation were also decreased following incubation with (±) linalool and (R)-(-) linalool compared to the OGD/R group (p < .01). In the same way, pre-treatment with (±) linalool and (R)-(-) linalool significantly reduced OGD/R-induced DNA injury compared to that seen in OGD/R group (p < .001). (±) Linalool and (R)-(-) linalool also restored Bax/Bcl-2 ratio and cleaved caspase-3 and caspase-9 (p < .001, p < .01) following ischemic injury. The neuroprotective effect of linalool against ischemic insult might be mediated by alleviation of oxidative stress and apoptosis.

Current Knowledge of the Antidepressant Activity of Chemical Compounds from Crocus sativus L

Psychotropic effect of Crocus sativus L. (family Iridaceae) biologically active chemical compounds are quite well documented and they can therefore be used in addition to the conventional pharmacological treatment of depression. This systematic review on antidepressant compounds in saffron crocus and their mechanisms of action and side effects is based on publications released between 1995−2022 and data indexed in 15 databases under the following search terms: antidepressant effect, central nervous system, Crocus sativus, cognitive impairement, crocin, crocetin, depression, dopamine, dopaminergic and serotonergic systems, picrocrocin, phytotherapy, neurotransmitters, safranal, saffron, serotonin, and biologically active compounds. The comparative analysis of the publications was based on 414 original research papers. The investigated literature indicates the effectiveness and safety of aqueous and alcoholic extracts and biologically active chemical compounds (alkaloids, anthocyanins, carotenoids, flavonoid, phenolic, saponins, and terpenoids) isolated from various organs (corms, leaves, flower petal, and stigmas) in adjuvant treatment of depression and anxiety. Monoamine reuptake inhibition, N-methyl-d-aspartate (NMDA) receptor antagonism, and gamma-aminobutyric acid (GABA)-α agonism are the main proposed mechanism of the antidepressant action. The antidepressant and neuroprotective effect of extract components is associated with their anti-inflammatory and antioxidant activity. The mechanism of their action, interactions with conventional drugs and other herbal preparations and the safety of use are not fully understood; therefore, further detailed research in this field is necessary. The presented results regarding the application of C. sativus in phytotherapy are promising in terms of the use of herbal preparations to support the treatment of depression. This is particularly important given the steady increase in the incidence of this disease worldwide and social effects.

Relaxing Effects of Breathing Pseudotsuga menziesii and Lavandula angustifolia Essential Oils on Psychophysiological Status in Older Adults

We evaluated the effects of breathing Pseudotsuga menziesii (P. menziesii) and Lavandula angustifolia (L. angustifolia) essential oils (EOs) during a horticultural activity on older adults. A total number of 92 older adult (71.2 ± 7.7 years old) participants were guided through a leaf printing procedure. In the meantime, water vapor and EOs were diffused in an orderly manner. The heart rate variability-related parameters as well as the brain waves were recorded. In addition, we also collected data for the State-Trait Anxiety Inventory-State (STAI-S) questionnaires before and after the whole indoor natural activity program. The physiological parameters including standard deviation of normal to normal intervals, normalized high frequency (nHF), and high alpha wave increased while the normalized low frequency (nLF), the ratio of LF-to-HF power, high beta wave, and gamma wave decreased following the breathing of P. menziesii and L. angustifolia EOs. These changes indicated a relaxing effect of breathing both EOs during a horticultural activity on older adults. Our results demonstrated a beneficial effect of P. menziesii EO which is as good as a well-known relaxant L. angustifolia EO. This notion was supported by the results of STAI-S. Here we developed an indoor natural activity program for older adults to promote physical and mental health.

Mechanisms underlying the inhibitory effects of linalool on Aspergillus flavus spore germination

Biogenic volatile organic compounds hold remarkable potential for controlling fungal decay in agro- and food products. Recently, we reported that linalool, the major volatile component of the Zanthoxylum schinifolium pericarp, showed great potential as a biofumigant to control Aspergillus flavus growth in postharvest grains. In this study, the inhibitory effects of linalool on A. flavus growth in stored grains and its underlying mechanism were investigated through transcriptomic and biochemical analyses. Linalool vapor at 800 μL/L can effectively prevent A. flavus growth in 22% moisture wheat grains. Linalool at 2 μL/mL completely inhibited the germination of A. flavus spores, and 10 μL/mL caused spore death. Scanning electron microscopy revealed that linalool treatment caused wrinkling and spore breakage. Transcriptomics showed that 3806 genes were significantly differentially expressed in A. flavus spores exposed to 2 μL/mL linalool, predominantly showing enrichment regarding the ribosome, DNA replication, glutathione metabolism, peroxisome, and MAPK signaling pathways. Flow cytometry showed that linalool treatment caused hyperpolarization of mitochondrial membrane potential. 4,6-Diamidino-2-phenylindole staining indicated that linalool caused DNA fragmentation in A. flavus spores, and monodansylcadaverine staining confirmed that linalool induced autophagy in A. flavus spores. We thus propose that linalool can damage the plasma membrane, cause mitochondrial dysfunction and DNA damage, and induce autophagy in A. flavus spores. These findings considerably improve our understanding of the mechanisms underlying the inhibitory effects of linalool on A. flavus, which is crucial regarding the development of applications to prevent postharvest grain spoilage due to A. flavus infestations. KEY POINTS: • The inhibitory potency of linalool on A. flavus spore germination was determined. • Transcriptomic analyses were performed to identify differentially expressed genes of A. flavus exposed to linalool. • A functional mechanism underlying the inhibitory effects of linalool on A. flavus spore germination is proposed.

Linalool as a Therapeutic and Medicinal Tool in Depression Treatment: A Review

Depression is a prevalent disease worldwide, limiting psychosocial functioning and thequality of life. Linalool is the main constituent of some essential oils from aromatic plants, representing about 70% of these volatile concentrates. Evidence of the linalool activity on the central nervous system, mainly acting as an antidepressant agent, is increasingly abundant. This review aimed to extend the knowledge of linalool's antidepressant action mechanisms, which is fundamental for future research, intending to highlight this natural compound as a new antidepressant phytomedication. A critical analysis is proposed here with probable hypotheses of the synergic mechanisms that support the evidence of antidepressant effects of the linalool. The literature search has been conducted in databases for published scientific articles before December 2020, using relevant keywords. Several pieces of evidence point to the anticonvulsant, sedative, and anxiolytic actions. In addition to these activities, other studies have revealed that linalool acts on the monoaminergic and neuroendocrine systems, inflammatory process, oxidative stress, and neurotrophic factors, such as BDNF, resulting in considerable advances in the knowledge of the etiology of depression. In this context, linalool emerges as a promising bioactive compound in the therapeutic arsenal, capable of interacting with numerous pathophysiological factors and acting on several targets. This review claims to contribute to future studies, highlighting the gaps in the linalool knowledge, such as its kinetics, doses, routes of administration, and multiple targets of interaction, to clarify its antidepressant activity.

Anxiolytic and antidepressant-like effects of monoterpene tetrahydrolinalool and in silico approach of new potential targets

INTRODUCTION- The drugs currently available for treatment of anxiety and depression act through modulation of the neurotransmission systems involved in the neurobiology of the disorder, yet they of-ten present side effects, which can impair patient adherence to treatment. METHOD- This, has driven the search for new molecules with anxiolytic and antidepressant potential. Aromatic plants are rich in essential oils, and their chemical constituents, such as monoterpenes, are be-ing studied for these disorders. This study aims to evaluate the anxiolytic and antidepressant-like poten-tial of the monoterpene tetrahydrolinalool in in vivo animal models, and review pharmacological targets with validation through molecular docking. Male Swiss mice (Mus musculus) were treated with THL (37.5-600 mg kg-1 p.o.) and submitted to the elevated plus maze, open field, rota rod, and forced swim tests. In the elevated plus-maze, THL at doses of 37.5 and 75 mg kg-1 induced a significant increase in the percentage of entries (72.7 and 64.3% respectively), and lengths of stay (80.3 and 76.8% respective-ly) in the open arms tests. RESULT- These doses did not compromise locomotor activity or motor coordination in the animals. In the open field, rota rod tests, and the forced swimming model, treatment with THL significantly reduced immobility times at doses of 150, 300, and 600 mg kg-1, and by respective percentages of 69.3, 60.9 and 68.7%. CONCLUSION- In molecular docking assay, which investigated potential targets, THL presented sat-isfactory energy values for: nNOs, SGC, IL-6, 5-HT1A, NMDAr, and D1. These demonstrate the po-tential of THL (a derivative of natural origin) in in vivo and in silico models, making it a drug candidate.

Developing Forest Therapy Programmes Based on the Health Benefits of Terpenes in Dominant Tree Species in Tara National Park (Serbia)

Numerous medical studies have shown the positive effects of forests on different aspects of human health. This study deals with the content of major terpenes in dominant coniferous species in Tara National Park, Serbia, in order to explore the potential for the development of a novel health tourism programme based on forest therapy. Main terpenes were analysed using a headspace-sampling technique coupled with gas-chromatography-mass spectrometry (Head-space-GC/MS). Needles of fir and spruce growing in the vicinity of hiking trails were investigated for possibilities to perform such therapy. Major detected terpenes were α-cadinol and spathulenol previously described as antiviral, antitumor, antimicrobial and immunomodulatory agents. The results of the study were favourable and worked well with the existing walking infrastructure in the observed area of the Tara Mountain, as they act as invaluable resources for designing the structured forest bathing walks. The study not only adds to the knowledge in the environmental and public health realm but also to tourism and sustainability studies.

Medicinal plants used in traditional Mayan medicine for the treatment of central nervous system disorders: An overview

ETHNOPHARMACOLOGICAL RELEVANCE

For thousands of years, different cultural groups have used and transformed natural resources for medicinal purposes focused on psychological or neurological conditions. Some of these are recognized as central nervous system (CNS) disorders and diseases, whereas other ethnopsychiatric interpretations are explained in culture-specific terms. In traditional Mayan medicine, several herbs have been part of treatments and rituals focused on cultural and ethnomedical concepts.

AIM OF REVIEW

This study aims to provide a comprehensive overview of the medicinal plants used in Mesoamerica by traditional healers and Mayan groups to CNS disorders and associate the traditional use with demonstrated pharmacological evidence to establish a solid foundation for directing future research.

METHODS

A systematic search for primary sources of plant use reports for traditional CNS-related remedies of Mesoamerica were obtained from library catalogs, thesis and scientific databases (PubMed, Scopus, Google Scholar; and Science Direct), and entered in a database with data analyzed in terms of the usage frequency, use by ethnic groups, plant endemism, and pharmacological investigation.

RESULTS

A total of 155 plants used for ethnopsychiatric conditions in Mesoamerica by Mayan groups were found, encompassing 127 native species. Of these, only 49 native species have reported in vitro or in vivo pharmacological analyses. The most commonly reported ethnopsychiatric conditions are related to anxiety, depression, memory loss, epilepsy, and insomnia. The extent of the scientific evidence available to understand the pharmacological application for their use against CNS disorders varied between different plant species, with the most prominent evidence shown by Annona cherimola, Justicia pectoralis, J. spicigera, Mimosa pudica, Persea americana, Petiveria alliacea, Piper amalago, Psidium guajava, Tagetes erecta and T. lucida.

CONCLUSION

Available pharmacological data suggest that different plant species used in traditional Mayan medicine may target the CNS, mainly related to GABA, serotonin, acetylcholine, or neuroprotective pathways. However, more research is required, given the limited data regarding mechanism of action at the preclinical in vivo level, identification of active compounds, scarce number of clinical studies, and the dearth of peer-reviewed studies.

Effect of Forest Therapy on Depression and Anxiety: A Systematic Review and Meta-Analysis

This systematic review and meta-analysis aimed to summarize the effects of forest therapy on depression and anxiety using data obtained from randomized controlled trials (RCTs) and quasi-experimental studies. We searched SCOPUS, PubMed, MEDLINE(EBSCO), Web of science, Embase, Korean Studies Information Service System, Research Information Sharing Service, and DBpia to identify relevant studies published from January 1990 to December 2020 and identified 20 relevant studies for the synthesis. The methodological quality of eligible primary studies was assessed by ROB 2.0 and ROBINS-I. Most primary studies were conducted in the Republic of Korea except for one study in Poland. Overall, forest therapy significantly improved depression (Hedges’s g = 1.133; 95% confidence interval (CI): −1.491 to −0.775) and anxiety (Hedges’s g = 1.715; 95% CI: −2.519 to −0.912). The quality assessment resulted in five RCTs that raised potential concerns in three and high risk in two. Fifteen quasi-experimental studies raised high for nine quasi-experimental studies and moderate for six studies. In conclusion, forest therapy is preventive management and non-pharmacologic treatment to improve depression and anxiety. However, the included studies lacked methodological rigor and required more comprehensive geographic application. Future research needs to determine optimal forest characteristics and systematic activities that can maximize the improvement of depression and anxiety.

Preparation and Antibacterial Activity of Thermo-Responsive Nanohydrogels from Qiai Essential Oil and Pluronic F108

Essential oils (EOs) have been used in cosmetics and food due to their antimicrobial and antiviral effects. However, the applications of EOs are compromised because of their poor aqueous solubility and high volatility. Qiai (Artemisia argyi Levl. et Van. var. argyi cv. Qiai) is a traditional Chinese herb and possesses strong antibacterial activity. Herein, we report an innovative formulation of EO as nanohydrogels, which were prepared through co-assembly of Qiai EO (QEO) and Pluronic F108 (PEG-b-PPG-b-PEG, or PF108) in aqueous solution. QEO was efficiently loaded in the PF108 micelles and formed nanohydrogels by heating the QEO/PF108 mixture solution to 37 °C, by the innate thermo-responsive property of PF108. The encapsulation efficiency and loading capacity of QEO reached 80.2% and 6.8%, respectively. QEO nanohydrogels were more stable than the free QEO with respect to volatilization. Sustained QEO release was achieved at body temperature using the QEO nanohydrogels, with the cumulative release rate reaching 95% in 35 h. In vitro antibacterial test indicated that the QEO nanohydrogels showed stronger antimicrobial activity against S. aureus and E. coli than the free QEO due to the enhanced stability and sustained-release characteristics. It has been attested that thermo-responsive QEO nanohydrogels have good potential as antibacterial cosmetics.

Immunostimulant and Antidepressant Effect of Natural Compounds in the Management of Covid-19 Symptoms

In recent years, the use of natural compounds as adjuvant treatments and alternatives to traditional pharmacological therapies has become increasingly popular. These compounds have a wide range of biological effects, such as: antioxidant, anti-aging, hypocholesterolizing, hypoglycemic, antitumoral, antidepressant, anxiolytic activity, etc. Almost all of these compounds are easily available and are contained in different foods. At the end of 2019 the Coronavirus SARS-CoV-2 appeared in China and quickly spread throughout the world, causing a pandemic. The most common symptoms of this infection are dry cough, fever, dyspnea, and in severe cases bilateral interstitial pneumonia, with consequences that can lead to death. The nations, in trying to prevent the spread of infection, have imposed social distancing and lockdown measures on their citizens. This had a strong psychological-social impact, leading to phobic, anxious and depressive states. Pharmacological therapy could be accompanied by treatment with several natural compounds, such as vitamins, baicalein, zinc and essential oils. These compounds possess marked immunostimulant activity, strengthening the immune response and mitigating interactions between the virus and the host cell. They also have an antidepressant effect, acting on certain neurotransmitters.

A Review of the Potential Use of Pinene and Linalool as Terpene-Based Medicines for Brain Health: Discovering Novel Therapeutics in the Flavours and Fragrances of Cannabis

"Medicinal cannabis" is defined as the use of cannabis-based products for the treatment of an illness. Investigations of cannabis compounds in psychiatric and neurological illnesses primarily focus on the major cannabinoids, cannabidiol (CBD) and Δ9-tetrahydrocannabinol (Δ9-THC), which are hypothesised to benefit multiple illnesses manifesting cognitive impairment, neurodegeneration and neuro-inflammation, as well as chronic pain, epilepsy and post-traumatic stress disorder, respectively. The cannabis plant contains >500 compounds, including terpenes responsible for the flavour and fragrance profiles of plants. Recently, research has begun providing evidence on the potential use of certain plant-derived terpenes in modern medicine, demonstrating anti-oxidant, anti-inflammatory, and neuroprotective effects of these compounds. This review examined the effects of two key terpenes, pinene and linalool, on parameters relevant to neurological and psychiatric disorders, highlighting gaps in the literature and recommendations for future research into terpene therapeutics. Overall, evidence is mostly limited to preclinical studies and well-designed clinical trials are lacking. Nevertheless, existing data suggests that pinene and linalool are relevant candidates for further investigation as novel medicines for illnesses, including stroke, ischemia, inflammatory and neuropathic pain (including migraine), cognitive impairment (relevant to Alzheimer's disease and ageing), insomnia, anxiety, and depression. Linalool and pinene influence multiple neurotransmitter, inflammatory and neurotrophic signals as well as behaviour, demonstrating psycho-activity (albeit non-intoxicating). Optimising the phytochemical profile of cannabis chemovars to yield therapeutic levels of beneficial terpenes and cannabinoids, such as linalool, pinene and CBD, could present a unique opportunity to discover novel medicines to treat psychiatric and neurological illnesses; however, further research is needed.

Natural volatile oils derived from herbal medicines: A promising therapy way for treating depressive disorder

Depression is a common global mental disorder that seriously harms human physical and mental health. With the development of society, the increase of pressure and the role of various other factors make the incidence of depression increase year by year. However, there is a lack of drugs that have a fast onset, significant effects, and few side effects. Some volatile oils from traditional natural herbal medicines are usually used to relieve depression and calm emotions, such as Lavender essential oil and Acorus tatarinowii essential oil. It was reported that these volatile oils, are easy to enter the brain through the blood-brain barrier and have good antidepressant effects with little toxicity and side effects. In this review, we summarized the classification of depression, and listed the history of using volatile oils to fight depression in some countries. Importantly, we summarized the anti-depressant natural volatile oils and their monomers from herbal medicine, discussed the anti-depressive mechanisms of the volatile oils from natural medicine. The volatile oils of natural medicine and antidepressant drugs were compared and analyzed, and the application of volatile oils was explained from the clinical use and administration routes. This review would be helpful for the development of potential anti-depressant medicine and provide new alternative treatments for depressive disorders.

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.

The Therapeutic Prospects of Naturally Occurring and Synthetic Indole Alkaloids for Depression and Anxiety Disorders

Depression and anxiety are the most common disorders among all age groups. Several antidepressant drugs including benzodiazepine, antidepressant tricyclics, azapirone, noradrenaline reuptake inhibitors, serotonin selective reuptake inhibitors, serotonin, noradrenaline reuptake inhibitors, and monoamine oxidase inhibitors have been used to treat these psychiatric disorders. However, these antidepressants are generally synthetic agents and can cause a wide range of side effects. The potential efficacy of plant-derived alkaloids has been reviewed against various neurodegenerative diseases including Alzheimer's disease, Huntington disease, Parkinson's disease, schizophrenia, and epilepsy. However, data correlating the indole alkaloids and antidepressant activity are limited. Natural products, especially plants and the marine environment, are rich sources of potential new drugs. Plants possess a variety of indole alkaloids, and compounds that have an indole moiety are related to serotonin, which is a neurotransmitter that regulates brain function and cognition, which in turn alleviates anxiety, and ensures a good mood and happiness. The present review is a summary of the bioactive compounds from plants and marine sources that contain the indole moiety, which can serve as potent antidepressants. The prospects of naturally occurring as well as synthetic indole alkaloids for the amelioration of anxiety and depression-related disorders, structure-activity relationship, and their therapeutic prospects have been discussed.

Forest Volatile Organic Compounds and Their Effects on Human Health: A State-of-the-Art Review

The aim of this research work is to analyze the chemistry and diversity of forest VOCs (volatile organic compounds) and to outline their evidence-based effects on health. This research work was designed as a narrative overview of the scientific literature. Inhaling forest VOCs like limonene and pinene can result in useful antioxidant and anti-inflammatory effects on the airways, and the pharmacological activity of some terpenes absorbed through inhalation may be also beneficial to promote brain functions by decreasing mental fatigue, inducing relaxation, and improving cognitive performance and mood. The tree composition can markedly influence the concentration of specific VOCs in the forest air, which also exhibits cyclic diurnal variations. Moreover, beneficial psychological and physiological effects of visiting a forest cannot be solely attributed to VOC inhalation but are due to a global and integrated stimulation of the five senses, induced by all specific characteristics of the natural environment, with the visual component probably playing a fundamental role in the overall effect. Globally, these findings can have useful implications for individual wellbeing, public health, and landscape design. Further clinical and environmental studies are advised, since the majority of the existing evidence is derived from laboratory findings.

Considering a Potential Role of Linalool as a Mood Stabilizer for Bipolar Disorder

Epidemiologic studies suggest that the lifetime prevalence of bipolar spectrum disorders ranges from 2.8 to 6.5 percent of the population. To decrease morbidity and mortality associated with disease progression, pharmacologic intervention is indicated for the majority of these patients. While a number of effective treatment regimens exist, many conventional medications have significant side effect profiles that adversely impact patients' short and long-term well-being. It is thus important to continue advancing and improving therapeutic options available to patients. This paper reviews the limitations of current treatments and examines the chemical compound Linalool, an alcohol found in many plant species, that may serve as an effective mood stabilizer. While relatively little is known about Linalool and bipolar disorder, the compound has been shown to have antiepileptic, anti-inflammatory, anxiolytic, anti-depressive, and neurotrophic effects, with mechanisms that are comparable to current bipolar disorder treatment options.

MYB21 interacts with MYC2 to control the expression of terpene synthase genes in flowers of Freesia hybrida and Arabidopsis thaliana

Previously, linalool was found to be the most abundant component among the cocktail of volatiles released from flowers of Freesia hybrida. Linalool formation is catalysed by monoterpene synthase TPS1. However, the regulatory network developmentally modulating the expression of the TPS1 gene in Freesia hybrida remains unexplored. In this study, three regulatory genes, FhMYB21L1, FhMYB21L2, and FhMYC2, were screened from 52 candidates. Two MYB transcription factor genes were synchronously expressed with FhTPS1 and could activate its expression significantly when overexpressed, and the binding of FhMYB21L2 to the MYBCORE sites in the FhTPS1 promoter was further confirmed, indicating a direct role in activation. FhMYC2 showed an inverse expression pattern compared with FhTPS1; its expression led to a decreased binding of FhMYB21 to the FhTPS1 promoter to reduce its activation capacity when co-expressed, suggesting a role for an MYB-bHLH complex in the regulation of the FhTPS1 gene. In Arabidopsis, both MYB21 and MYC2 regulators were shown to activate the expression of sesquiterpene synthase genes, and the regulatory roles of AtMYB21 and AtMYC2 in the expression of the linalool synthase gene were also confirmed, implying conserved functions of the MYB-bHLH complex in these two evolutionarily divergent plants. Moreover, the expression ratio between MYB21 and MYC2 orthologues might be a determinant factor in floral linalool emission.

Chemical Compositions of Commercial Essential Oils From Coriandrum sativum Fruits and Aerial Parts

Coriander and cilantro, the fruit and herb of Coriandrum sativum, are popular additives in various cuisines worldwide. The essential oils derived from coriander and cilantro are also popular and have shown some remarkable biological properties and health benefits. In this report, we have analyzed the essential oil compositions of 19 commercial coriander and 28 commercial cilantro essential oil samples by gas chromatography–mass spectrometry (GC–MS) techniques. In addition, 5 coriander and 4 cilantro commercial essential oil samples were analyzed by chiral GC–MS. Commercial coriander essential oil is dominated by linalool (62.2%-76.7%) with lesser quantities of α-pinene (0.3%-11.4%), γ-terpinene (0.6%-11.6%), and camphor (0.0%-5.5%). Commercial cilantro essential oil is composed largely of (2 E)-decenal (16.0%-46.6%), linalool (11.8%-29.8%), (2 E)-decen-1-ol (0.0%-24.7%), decanal (5.2%-18.7%), (2 E)-dodecenal (4.1%-8.7%), and 1-decanol (0.0%-9.5%). The enantiomeric distribution of linalool was 87% (+)-linalool:13% (−)-linalool in both coriander and cilantro essential oils, while α-pinene was 93% (+):7% (−) in coriander, 90% (+):10% (−) in cilantro; and (+)-camphor:(−)-camphor was 13%:87% in both essential oils. Chiral GC–MS analysis was able to detect an adulterated coriander essential oil sample. The data provided in this study serves to establish a baseline for future evaluations of these essential oils as well as a screen for authenticity or adulteration.

Mutagenesis and Adaptation of the Psychrotrophic Fungus Chrysosporium pannorum A-1 as a Method for Improving β-pinene Bioconversion

Mutagenesis and adaptation of the psychrotrophic fungus Chrysosporium pannorum A-1 to the toxic substrate β-pinene were used to obtain a biocatalyst with increased resistance to this terpene and improved bioconversion properties. Mutants of the parental strain were induced with UV light and N-methyl-N'-nitro-N-nitrosoguanidine. Mutants resistant to β-pinene were isolated using agar plates with a linear gradient of substrate concentrations. Active mutants were selected based on their general metabolic activity (GMA) expressed as oxygen consumption rate. Compared to the parental strain, the most active mutant showed an enhanced biotransformation ability to convert β-pinene to trans-pinocarveol (315 mg per g of dry mycelium), a 4.3-fold greater biocatalytic activity, and a higher resistance to H2O2-induced oxidative stress. Biotransformation using adapted mutants yielded twice as much trans-pinocarveol as the reaction catalyzed by non-adapted mutants. The results indicate that mutagenesis and adaptation of C. pannorum A-1 is an effective method of enhancing β-bioconversion of terpenes.

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'.

Inhalation Administration of the Bicyclic Ethers 1,8- and 1,4-cineole Prevent Anxiety and Depressive-Like Behaviours in Mice

The anxiolytic and antidepressant-like activities of the naturally occurring monoterpene 1,8-cineole and its structural isomer 1,4-cineole were evaluated in mice via inhalation administration at doses ranging from 4 × 10-6 to 4 × 10-1 mg per 400 μL of triethyl citrate. Mice were tested for anxiety-like behaviours by using the light-dark box test (LDB) and marble-burying test (MBT) and for depression-like symptoms by using the forced swimming test (FST) and tail suspension test (TST). Diazepam and fluoxetine were used as standard drugs for anxiolytic and antidepressant tests, respectively. The results showed that 1,8-cineole at 4 × 10-4 mg, and 1,4-cineole at 4 × 10-4 and 4 × 10-3 mg significantly increased the amount of time spent in the light box and the number of entries in the light box in the LDB as well as reduced the number of marbles buried in the MBT relative to those in the control, suggesting an anxiolytic effect. Similarly, 1,8-cineole at 4 × 10-4 and 4 × 10-2 mg and 1,4-cineole at doses of 4 × 10-4 to 4 × 10-2 mg significantly reduced immobility times in the FST and TST relative to those of the control, suggesting an antidepressant activity. The role of the GABAA/benzodiazepine receptor system in the anxiolytic effects of 1,8- and 1,4-cineole was investigated through co-administration of flumazenil, a GABAergic system antagonist. Flumazenil reversed the effects of diazepam and 1,8-cineole, suggesting that 1,8-cineole affects the GABAA/benzodiazepine receptors. Collectively, the results suggest that inhaled 1,8- and 1,4-cineole prevented anxiety and depressive-like symptoms in classic mice models.

Terpenoids, Cannabimimetic Ligands, beyond the Cannabis Plant

Medicinal use of Cannabis sativa L. has an extensive history and it was essential in the discovery of phytocannabinoids, including the Cannabis major psychoactive compound-Δ9-tetrahydrocannabinol (Δ9-THC)-as well as the G-protein-coupled cannabinoid receptors (CBR), named cannabinoid receptor type-1 (CB1R) and cannabinoid receptor type-2 (CB2R), both part of the now known endocannabinoid system (ECS). Cannabinoids is a vast term that defines several compounds that have been characterized in three categories: (i) endogenous, (ii) synthetic, and (iii) phytocannabinoids, and are able to modulate the CBR and ECS. Particularly, phytocannabinoids are natural terpenoids or phenolic compounds derived from Cannabis sativa. However, these terpenoids and phenolic compounds can also be derived from other plants (non-cannabinoids) and still induce cannabinoid-like properties. Cannabimimetic ligands, beyond the Cannabis plant, can act as CBR agonists or antagonists, or ECS enzyme inhibitors, besides being able of playing a role in immune-mediated inflammatory and infectious diseases, neuroinflammatory, neurological, and neurodegenerative diseases, as well as in cancer, and autoimmunity by itself. In this review, we summarize and critically highlight past, present, and future progress on the understanding of the role of cannabinoid-like molecules, mainly terpenes, as prospective therapeutics for different pathological conditions.

Hops compounds modulatory effects and 6-prenylnaringenin dual mode of action on GABAA receptors

Hops (Humulus lupulus L.), a major component of beer, contain potentially neuroactive compounds that made it useful in traditional medicine as a sleeping aid. The present study aims to investigate the individual components in hops acting as allosteric modulators in GABA_A receptors and bring further insight into the mode of action behind the sedative properties of hops. GABA-potentiating effects were measured using [³H]ethynylbicycloorthobenzoate (EBOB) radioligand binding assay in native GABA_A receptors. Flumazenil sensitivity of GABA-potentiating effects, [³H]Ro 15-4513, and [³H]flunitrazepam binding assays were used to examine the binding to the classical benzodiazepines site. Humulone (alpha acid) and 6-prenylnaringenin (prenylflavonoid) were the most potent compounds displaying a modulatory activity at low micromolar concentrations. Humulone and 6-prenylnaringenin potentiated GABA-induced displacement of [³H]EBOB binding in a concentration-dependent manner where the IC₅₀ values for this potentiation in native GABA_A receptors were 3.2 μM and 3.7 μM, respectively. Flumazenil had no significant effects on humulone- or 6-prenylnaringenin-induced displacement of [³H]EBOB binding. [³H]Ro 15-4513 and [³H]flunitrazepam displacements were only minor with humulone but surprisingly prominent with 6-prenylnaringenin despite its flumazenil-insensitive modulatory activity. Thus, we applied molecular docking methods to investigate putative binding sites and poses of 6-prenylnaringenin at the GABA_A receptor α1β2γ2 isoform. Radioligand binding and docking results suggest a dual mode of action by 6-prenylnaringenin on GABA_A receptors where it may act as a positive allosteric modulator at α+β- binding interface as well as a null modulator at the flumazenil-sensitive α+γ2- binding interface.

Anti-listeria Activities of Linalool and Its Mechanism Revealed by Comparative Transcriptome Analysis

Listeria monocytogenes, which causes serious foodborne infections and public health problems worldwide, is one of the most important foodborne pathogens. Linalool has been identified as an antimicrobial agent against some microorganism, but its mechanism of action is currently unclear. Here, we investigated the efficacy of linalool against L. monocytogenes while planktonic and as a biofilm and explored potential mechanisms of action. Linalool exhibited strong anti-listeria activity in the planktonic stage. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations revealed seven stages were classified of cells at microscopic level. Mesosome-like structures were observed for the first time in L. monocytogenes after linalool treatment. Linalool also showed significant anti-biofilm activity through both dispersal and killing of cells in the biofilm based on confocal scanning laser microscopy (CLSM) and SEM imaging, crystal violet staining, XTT and COMSTAT assays. Moreover, comparative transcriptome analysis demonstrated many potential mechanisms of action for linalool and some important pathways were screened out through the analysis of GO enrichment and KEGG. Our study provides evidence that linalool exhibits a strong antimicrobial activity against both the planktonic and biofilm forms of L. monocytogenes and gives insight into its mechanism of action.

Therapeutic and Medicinal Uses of Terpenes

Terpenes, also known as terpenoids are the largest and most diverse group of naturally occurring compounds. Based on the number of isoprene units they have, they are classified as mono, di, tri, tetra, and sesquiterpenes. They are mostly found in plants and form the major constituent of essential oils from plants. Among the natural products that provide medical benefits for an organism, terpenes play a major and variety of roles. The common plant sources of terpenes are tea, thyme, cannabis, Spanish sage, and citrus fruits (e.g., lemon, orange, mandarin). Terpenes have a wide range of medicinal uses among which antiplasmodial activity is notable as its mechanism of action is similar to the popular antimalarial drug in use—chloroquine. Monoterpenes specifically are widely studied for their antiviral property. With growing incidents of cancer and diabetes in modern world, terpenes also have the potential to serve as anticancer and antidiabetic reagents. Along with these properties, terpenes also allow for flexibility in route of administration and suppression of side effects. Certain terpenes were widely used in natural folk medicine. One such terpene is curcumin which holds anti-inflammatory, antioxidant, anticancer, antiseptic, antiplasmodial, astringent, digestive, diuretic, and many other properties. Curcumin has also become a recent trend in healthy foods and open doors for several medical researches. This chapter summarizes the various terpenes, their sources, medicinal properties, mechanism of action, and the recent studies that are underway for designing terpenes as a lead molecule in the modern medicine.

Bioconversion of essential oil components of Perilla frutescens by Saccharomyces cerevisiae

The essential oil of perilla (Perilla frutescens) contains volatile low molecular weight compounds such as monoterpenes and phenylpropenes. The composition of the essential oil is classified into about ten chemotypes. The biosynthesis of these constituents is strictly controlled genetically. Among the compounds contained in perilla essential oil, the bioconversion of pure compounds such as perillaldehyde, limonene, and citral has been reported, but that of many other components has not. In addition, changes in the volatile components of raw plant material during brewing have also been investigated for wine and beer. In this study, we examined the bioconversion of perilla essential oil components by Saccharomyces cerevisiae during the brewing of liquor with perilla leaves. S. cerevisiae was added to the ethanol-water extract of dried leaves of P. frutescens and P. citriodora for seven essential oil types: perillaldehyde type, piperitenone type, perillene type, perillaketone type, elsholtziaketone type, citral type, and phenylpropanoid type. Volatile compounds in the reaction mixtures were analyzed by solid-phase microextraction (SPME)-GC-MS, revealing bioconversion of perillaldehyde, isoegomaketone, neral, and geranial by S. cerevisiae. Analysis of the conversion products suggests that they were formed by the reduction of C=C bonds and aldehydes, as well as by esterification and dehydration reactions.

Chemical Composition and Antimicrobial Activity of the Leaf and Twig Essential Oils of Magnolia hypolampra Growing in Na Hang Nature Reserve, Tuyen Quang Province of Vietnam

The leaf and twig essential oils of Magnolia hypolampra, growing wild in Na Hang Nature Reserve, Tuyen Quang province of Vietnam, were obtained by hydrodistillation and analyzed by gas chromatography-mass spectrometry. The oil yield calculated on a dry weight basis from leaves of M. hypolampra was very high (1.62%, v/w), while that from twigs was much lower (0.07%, v/w). The essential oils were dominated by monoterpenoids (74.3% and 84.8%) and sesquiterpenoids (24.4% and 13.3%) with β-pinene (36.5% and 41.3%), α-pinene (23.7% and 24.4%), and germacrene D (14.6% and 5.8%) as respective major components. Antibiotic activity of the essential oil samples was tested against Gram-positive bacteria Staphylococcus aureus, Gram-negative bacteria Escherichia coli, and yeast Candida albicans using an agar disk diffusion method. Both the leaf and twig oils showed strong inhibition against all 3 tested microorganism strains with inhibition zones from 18.5 to 30.5 mm and from 45.5 to 46 mm, respectively. Minimum inhibitory concentration of the essential oils was determined using microdilution broth susceptibility assay against 7 test microorganism strains including Bacillus subtilis, Lactobacillus fermentum, Salmonella enterica, Pseudomonas aeruginosa, and 3 abovementioned strains. Minimum inhibitory concentration values of the essential oil from the twigs were from 2.0 to 8.2 mg/mL, while those from the leaves were from 4.1 to 16.4 mg/mL.