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

Kokedama and essential oils had a relaxing psychophysiological effect on Taiwanese women during the COVID-19 pandemic

BACKGROUND

During the COVID-19 pandemic, we designed an indoor nature activity program for citizens with a relaxing effect similar to forest bathing to promote their physical and mental health. We integrated an indoor horticultural activity (Kokedama) with the breathing of Pseudotsuga menziesii (P. menziesii) and Lavandula angustifolia (L. angustifolia) essential oils (EOs) with the goal of creating a nature-inspired environment in an indoor setting where participants would feel as if immersed in a forest atmosphere.

METHODS

Taiwanese women participated in the experiment, using two Saturday mornings, one Saturday in a university classroom in the city center; and the other Saturday in a workshop in a Suburban Park. Intra-group comparisons were used to assess the Physiological responses to urban and suburban environmental stimuli and measured self-reported psychological responses. We recorded parameters associated with heart-rate variability and brainwaves. We also administered the State-Trait Anxiety Inventory-State (STAI-S) questionnaire before and after the participants had completed the entire program.

RESULTS

After the participants had breathed the P. menziesii and L. angustifolia EOs, the levels of some physiological parameters increased (standard deviation of normal-to-normal intervals, normalized high frequency, and high alpha wave) and those of others decreased (normalized low frequency, low- to high-frequency ratio power, high beta wave, and gamma wave). These findings were corroborated by the data from the STAI-S questionnaires.

CONCLUSIONS

The psychophysiological data from this study provide significant scientific evidence for the health benefits of an indoor nature activity program in women.

Lavender oil preparation Silexan is effective in mild-to-moderate major depression: a randomized, placebo- and reference-controlled trial

Anxiety and depressive disorders have overlapping symptoms and share common neurobiological pathways. Antidepressant drugs have been demonstrated to be efficacious in anxiety as well. Vice versa, it may also be promising to investigate the efficacy of anxiolytic drugs such as silexan in major depressive disorder (MDD). Patients with a mild or moderate, single or recurrent episode of MDD and a total score of 19-34 points on the Montgomery Åsberg Depression Rating Scale (MADRS) were randomized to receive 1 × 80 mg/d silexan, 1 × 50 mg/d sertraline, or placebo double-blind, double-dummy for 56 days. The primary outcome measure was the MADRS total score change between baseline and treatment end. Treatment groups were compared using a treatment policy estimand. 498 subjects (silexan 170, sertraline 171, placebo 157) were treated and analyzed. After 8 weeks, silexan and sertraline were superior to placebo for MADRS total score reduction, with absolute differences to placebo of 2.17 (95% confidence interval: 0.58; 3.76) points and 2.59 (1.02; 4.17) points, respectively (p < 0.01). Moreover, silexan was superior to placebo for alleviation of functional impairment according to the Sheehan Disability Scale with a difference of 2.40 (1.04; 3.76) points (p < 0.001). Both treatments were well tolerated; eructation was the most frequent adverse effect of silexan. The study confirms the antidepressant efficacy of silexan in mild or moderate MDD, including significant improvements in the subjects' functional capacity. The results for sertraline confirm the assay sensitivity of the trial. Both drugs were well tolerated.Trial registrationEudraCT2020-000688-22 first entered on 12/08/2020.

Baseline symptom severity and efficacy of Silexan in patients with anxiety disorders: A symptom-based, patient-level analysis of randomized, placebo-controlled trials

The influence of baseline severity on the efficacy of Silexan, a proprietary essential oil from Lavandula angustifolia, in anxiety disorders has not been investigated in a pooled dataset. We report on an individual patient data analysis of all five double-blind, randomized, placebo-controlled trials with Silexan in anxiety disorders. Eligible participants received Silexan 80 mg/d or placebo for 10 weeks. Analyses were based on the Hamilton Anxiety Rating Scale (HAMA), its psychic and somatic anxiety subscores, and the Clinical Global Impressions (CGI) scale. To correlate baseline severity with outcome, patients were segregated into mild, moderate, and severe cases. Altogether 1,172 patients (Silexan, n = 587; placebo, n = 585) were analyzed. For the HAMA total score, we found a significant association between the score at baseline and the treatment effect of Silexan versus placebo at week 10 (p < 0.001). HAMA items from the somatic domain scored lower at baseline and showed less improvement than items from the psychic domain, particularly in patients with mild or moderate baseline symptoms. For CGI item 2 (global improvement), significant efficacy favoring Silexan were observed in mild, moderate, and severe baseline symptom severity. Although significant improvements were found for all subsets, the more severe the initial symptoms, the greater the treatment effects documented by the HAMA. Overall this analysis confirms that Silexan is an effective treatment option in early or mild stages of anxiety disorder. Given its favorable safety profile, Silexan can thus fill a therapeutic gap in the treatment of (subsyndromal) anxiety disorders.

Multi-target drugs for the treatment of cognitive impairment and fatigue in post-COVID syndrome: focus on Ginkgo biloba and Rhodiola rosea

Cognitive impairment, depression and (mental) fatigue represent the most frequent neuropsychiatric symptoms of the post-COVID syndrome. Neuroinflammation, oxidative stress and mitochondrial dysfunction have been identified as common pathophysiological mechanisms underlying these symptoms. Attempts to treat post-COVID-associated cognitive impairment and fatigue with different drugs available for other diseases have not yet been successful. One probable explanation could be that these drugs work by one specific mechanism of action only and not in a broad multi-target way. Therefore, they will not address the broad pathophysiological spectrum possibly responsible for cognitive impairment, depression and fatigue in post-COVID syndrome. Notably, nearly all drugs currently under investigation for fatigue in post-COVID syndrome are rather addressing one single target instead of the several pathomechanisms underlying this condition. Contrary to this approach, herbal drugs often consist of many different ingredients with different pharmacological properties and pharmacological targets. Therefore, these drugs might be a promising approach for the treatment of the broad symptomatic presentation and the pathophysiological mechanisms of cognitive impairment and fatigue following a SARS-CoV-2 infection. Of these herbal drugs, extracts of Ginkgo biloba and Rhodiola rosea probably are the best investigated candidates. Their broad pharmacological spectrum in vitro and in vivo includes anti-oxidative, anti-inflammatory, antidepressant as well as properties reducing cognitive impairment and fatigue. In several studies, both drugs showed positive effects on physical and mental fatigue and impaired cognition. Moreover, depressive symptoms were also reduced in some studies. However, even if these results are promising, the data are still preliminary and require additional proof by further studies.

Efficacy of Silexan in patients with anxiety disorders: a meta-analysis of randomized, placebo-controlled trials

INTRODUCTION

We report on a meta-analysis of Silexan, a proprietary active substance produced from Lavandula angustifolia, in subthreshold anxiety, mixed anxiety and depressive disorder (MADD), and generalized anxiety disorder (GAD).

METHODS

The present analyses are based on all currently completed 5 double-blind, randomized, placebo-controlled trials investigating Silexan in adult out-patients who received Silexan 1 × 80 mg/day or placebo for ten weeks according to random assignment (n = 1213). Efficacy was assessed based on the Hamilton Anxiety Rating Scale (HAMA), several anxiety self-rating scales, the Clinical Global Impression (CGI) scale, and the Short Form-36 (SF-36) health status questionnaire.

RESULTS

After ten weeks' treatment, Silexan was significantly superior to placebo in reducing the HAMA total score (including the psychic and somatic anxiety sub-scores) and self-rated anxiety. Based on a ≥ 50% HAMA total score reduction, the responder rate ratio was 1.34 favoring Silexan, and the rate ratio of subjects much or very much improved according to the CGI was 1.51. Silexan was also significantly superior in improving the physical and mental health summary scores of the SF-36. There were no significant between-group differences concerning the occurrence of adverse events (AEs), serious AEs, and premature withdrawal due to AEs.

CONCLUSIONS

This meta-analysis demonstrates that Silexan exerts significant anxiolytic effects in subthreshold anxiety, GAD and MADD that were consistently reflected in investigator ratings and patient-reported outcomes, including improvement of health-related life-quality, while showing favorable tolerability and safety.

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.

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.

Allelopathic Properties of Lamiaceae Species: Prospects and Challenges to Use in Agriculture

Herbicide resistance due to the increasing reliance on herbicides is a near-term challenge for the world’s agriculture. This has led to a desire to develop new herbicides with a novel mode of action, to address resistance in weed species. Lamiaceae, a large dicotyledonous plant family, is very well known for the multitudinous pharmacological and toxicological properties of its member species. Moreover, many species of this family are significant for their allelopathic activity in natural and laboratory settings. Thus, plants in Lamiaceae have the potential to be sources of alternative herbicides. However, gaps in our knowledge need to be addressed prior to adopting these allelopathic activities in agriculture. Therefore, we review the existing state of knowledge about the Lamiaceae family, the reported allelopathic properties of plant extracts, and their isolated allelochemicals under laboratory, greenhouse, and field conditions. In addition, we offer a perspective on existing challenges and future opportunities for adopting the allelopathic properties of Lamiaceae plant species for green agriculture.

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.

Effects of Lavender on Anxiety, Depression, and Physiological Parameters: Systematic Review and Meta-Analysis

PURPOSE

The recent evidence suggested substantial anxiolytic efficacy of lavender. The aim of this study was to examine the efficacy of lavender for anxiety, depression, and physiological parameters and to elucidate the differential effects of lavender on anxiety and depression by study characteristics.

METHODS

A systematic review and meta-analysis was performed following the PRISMA guidelines. We searched PubMed, Embase, Cochrane Library, Web of Science, and Cumulative Index of Nursing and Allied Health Literature databases for randomized controlled trials investigating the efficacy of lavender on anxiety, depression, or physiological parameters in humans. We assessed the risk of bias within studies with the revised Cochrane risk of bias tool for randomized trials. We used random effect model to estimate the average effect and computed bias-corrected standardized mean difference as effect size metric, Hedges' ĝ for all outcomes.

RESULTS

Lavender was superior to placebo or no treatment in reducing anxiety (Hedges' ĝ = -0.72, 95% confidence interval [CI] -0.90 to -0.55, p value <.001), depression (Hedges' ĝ = -0.43, 95% CI, -0.59 to -0.27, p value <.001), and systolic blood pressure (Hedges' ĝ = -0.23, 95% CI, -0.41to -0.05, p value = .01). The moderator analysis by meta-regression indicated that route of administration accounted 6.5% (p value = .187) for the heterogeneity in anxiolytic effects, sessions of treatment accounted 13.2% (p value = .055), and participants' health state accounted 8.9% (p value = .131) for the variance in anxiolytic effects.

CONCLUSION

Lavender aromatherapy showed substantial effect in reducing anxiety and depression, and sessions of administration increased the anxiolytic effects. The effects on physiological parameters showed small with inconsistent significances and randomized controlled trials on the effect of lavender on depression were scarce. Future trials on depression and physiological parameters are recommended, and increasing the sessions of administration is recommended.

Nutraceuticals in mental diseases - Bridging the gap between traditional use and modern pharmacology

In evidence-based pharmacotherapy, the complexity of etiopathogenesis and pathophysiology of mental diseases has attracted comparably little consideration so far. The choice of currently available pharmacotherapies is predominantly guided by specific clinical phenotypes and is limited by low response rates and clinically relevant side effects. Nutraceuticals typically represent multicomponent compounds and may offer high therapeutic potential, by simultaneously addressing multiple aspects in mental disease pathogenesis with rather little side effects. Here, recent pharmacological research on natural products is assessed with focus on a multitarget therapeutic concept, based on shared molecular mechanisms, and in particular, on how far nutraceuticals might address such multitargets. Overcoming deficits regarding clearly defined compositions, concentration-dependent and causative structure-activity-response relationships, evaluation of bioavailability, metabolic fate, and long-term safety are crucial for translating potential plant-based drug candidates into proof-of-concept clinical studies.

Neuro-nutraceuticals: Natural products nourish the brain but be aware of contrary effects

In this Special Issue on "Nutraceuticals: Molecular and Functional Insights into how Natural Products Nourish the Brain", the editors bring together contributions from experts in nutraceutical research to provide a contemporary overview of how select chemically identified molecules from natural products can beneficially affect brain function at the molecular level. Other contributions address the holistic benefit of herbal medicines and their multi-targeted actions, which improve brain function in diverse cellular and animal models of brain injury. Not only are new targets for nutraceuticals reported, but their benefits on neurobehavioural problems are elucidated in conditions as diverse as obesity and menopause. Inflammation in neuropathologies, including Alzheimer's disease (AD), remains a huge focus and diverse nutraceuticals demonstrate therapeutic applicability via glial-mediated actions. While contrary actions should be borne in mind in the search for novel neurotherapeutics, the great promise offered by herbal medicines and their newly identified active principles offers unique options for the management of diverse neurological and psychiatric conditions.

Anxiolytic Effect of Two Tobacco Essential Oils (Nicotiana tabacum Linn.) on Mice

Tobacco (Nicotiana tabacum Linn.) is a famous traditional herb used in folk medicine. The essential oils of tobacco have been demonstrated in modern studies to possess antioxidant, anti-inflammatory, and neuroprotective properties, while its anxiolytic effect has not been reported. The purpose of this study was to evaluate the anxiolytic effect of Yunnan tobacco essential oil (YTO) and Zimbabwe tobacco essential oil (ZTO) on mice. The constituents of YTO and ZTO were analyzed by GC/MS. The anxiolytic effect of YTO and ZTO (0.1%, 1%, and 10%, v/v) on male ICR mice was evaluated in the light-dark box test (LDB) and the elevated plus maze test (EPM) test via inhalation and transdermal administration. After the behavioral tests, salivary corticosterone levels in mice were measured. The behavioral analysis showed that the administration of both YTO and ZTO elevated the time that the mice spent in the light chamber in the LDB test compared to the untreated control. In the EPM test, YTO and ZTO increased the time spent in open arms and the number of entries into the open arms. In addition, both YTO and ZTO significantly decreased salivary corticosterone levels in mice (p ≤ 0.001). In summary, our results demonstrated that inhalation and transdermal administration of both YTO and ZTO showed anxiolytic effect on male ICR mice.