Olfactory training with essential oils for patients with post-COVID-19 smell dysfunction: A case series.

Introduction: It is estimated that up to one third of COVID-19 patients can develop long-lasting smell dysfunction. Viral infections, especially COVID-19, can cause anosmia through different pathomechanisms, and different strategies have been proposed for effectively managing post-COVID-19 olfactory dysfunction in clinical practice, with olfactory training being recommended as a first-line treatment option. Methods: This report describes a non-consecutive series of clinical cases. After COVID-19, eight cases (5 females, 3 males) of adult patients with long-lasting (3+ months) post-viral smell dysfunction followed a 30-day olfactory training protocol with a set of plant-derived essential oils. At baseline and at the end of the treatment, the patients were administered the Assessment of Self-reported Olfactory Functioning (ASOF) questionnaire, an inventory used to measure olfactory dysfunction and health-related quality of life. Results: For any of the outcomes assessed with the ASOF scale, a significant improvement from baseline was reported, even though mean value ameliorations were more pronounced for olfactory function per se (Subjective Olfactory Capability: from 3.6 to 5.6 out of 10; Self-Reported capability of Perceiving specific odors: from 1.8 to 3.0 out of 5), rather than for health-related quality of life (Olfactory-Related Quality of life: from 2.9 to 3.9 out of 6). Conclusions: It was observed that patients with long-lasting COVID-19-related smell dysfunction improved after a 30-day olfactory training protocol. Further controlled clinical studies would be useful to better investigate the role of olfactory training in patients with postviral smell dysfunction.

Appropriate use of essential oils and their components in the management of upper respiratory tract symptoms in patients with COVID-19.

INTRODUCTION: The involvement of the upper respiratory tract is common in COVID-19, and the majority of patients are treated at home with a mild-to-moderate form of the disease. Many approaches based on essential oils have been proposed for the symptomatic treatment of COVID-19. This work aims to outline the potential and safe evidence-based uses of essential oils and their major components for the clinical management of mild respiratory symptoms caused by uncomplicated coronavirus infections, including SARS-CoV-2. Due to their wide use, a focus on the constituents eucalyptol and menthol has been provided. METHODS: An overview of the scientific literature with a critical discussion of retrieved evidence and clinical recommendations. RESULTS: In general, eucalyptol and essential oils or blends whose content is rich in it, may be used as an integrative remedy for the symptomatic improvement of patients with mild and uncomplicated infections caused by coronaviruses. Menthol is not recommended in patients with COVID-19, due to a potential reduction of the self-perception of dyspnea, which can lead infected patients to underestimate the actual disease severity and to delay medical attention. DISCUSSION: Based on available evidence, symptomatic remedies for COVID-19, such as essential oils and their isolated compounds, can be useful, but are not an alternative to standard medical therapy and do not exempt patients from following precautionary measures issued by health authorities. Clinical recommendations on the appropriate use of essential oils for the management of upper airway symptoms of COVID-19 are provided. Further studies on the topic are advised.

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.

Comparative and Functional Screening of Three Species Traditionally used as Antidepressants: Valeriana officinalis L., Valeriana jatamansi Jones ex Roxb. and Nardostachys jatamansi (D.Don) DC.

The essential oils (EOs) of three Caprifoliaceae species, the Eurasiatic Valeriana officinalis (Vo), the Himalayan Valeriana jatamansi (Vj) and Nardostachys jatamansi (Nj), are traditionally used to treat neurological disorders. Roots/rhizomes micromorphology, DNA barcoding and EOs phytochemical characterization were carried out, while biological effects on the nervous system were assessed by acetylcholinesterase (AChE) inhibitory activity and microelectrode arrays (MEA). Nj showed the highest inhibitory activity on AChE (IC50 67.15 µg/mL) followed by Vo (IC50 127.30 µg/mL) and Vj (IC50 246.84 µg/mL). MEA analyses on rat cortical neurons, carried out by recording mean firing rate (MFR) and mean bursting rate (MBR), revealed stronger inhibition by Nj (IC50 18.8 and 11.1 µg/mL) and Vo (16.5 and 22.5 µg/mL), compared with Vj (68.5 and 89.3 µg/mL). These results could be related to different EO compositions, since sesquiterpenes and monoterpenes significantly contribute to the observed effects, but the presence of oxygenated compounds such as aldehydes and ketones is a discriminating factor in determining the order of potency. Our multidisciplinary approach represents an important tool to avoid the adulteration of herbal drugs and permits the evaluation of the effectiveness of EOs that could be used for a wide range of therapeutic applications.

Chemical Composition and Biological Activities of the Essential Oils of Leptospermum petersonii and Eucalyptus gunnii.

The aim of this study was to characterize the chemical composition and to evaluate the antimicrobial and phytotoxic properties of the essential oils (EOs) obtained from leaves of Leptospermum petersonii chemotype "Variety B" and Eucalyptus gunnii, native to Australia. Geranyl acetate, γ-terpinene, geraniol, terpinolene, α-pinene, p-cimene, and linalool were the main components in L. petersonii EO, confirming also the existence of several chemotypes in such taxa; on the other hand, 1,8-cineole, trans-sabinene hydrate acetate, globulol, longicyclene, terpinolene, and camphene were present in major amounts in the E. gunnii EO. Chemical analysis of L. petersonii revealed that it belongs to the variety "B." E. gunnii EO showed good antibacterial activity, with an MIC of 0.5 and 2 µg/mL against Staphylococcus aureus, and Pectobacterium carotovorum, respectively. The activity of E. gunnii EO was stronger than L. petersonii EO, whose maximum MIC reached 5 µg/mL. E. gunnii and L. petersonii EOs were particularly effective in inhibiting the biofilm formation by S. aureus, already at a concentration of 0.01 µg/mL. The other strains were resistant to both EOs up to a dose of 0.05 µg/mL. The maximum inhibition on biofilm formed by P. carotovorum was recorded for E. gunnii EO, reaching a value of 93.12% at 1.0 µg/mL. This is the first manuscript which studies the biofilm inhibition by EOs and evaluates their effects on biofilm metabolism. Both EOs were more effective against P. carotovorum. In addition, even though L. petersonii EO 0.1 µg/mL was unable to inhibit biofilm formation by Escherichia coli, it decreased the metabolic activity of the biofilm to 78.55% compared to control; furthermore, despite it inducing a relatively low inhibition (66.67%) on biofilm formation, it markedly affected metabolic activity, which decreased to 16.09% with respect to the control. On the contrary, L. petersonii EO 0.5 µg/mL induced a 79.88% inhibition of S. aureus biofilm, maintaining a high metabolic activity (90.89%) compared to the control. Moreover, this EO showed inhibitory activity against radical elongation of Solanum lycopersicum and the germination of radish. On the contrary, E. gunnii EO showed no phytotoxic activity.

Characterization and Phytotoxicity Assessment of Essential Oils from Plant Byproducts.

The present work describes the chemical characterization and the phytotoxicity assessment of essential oils (EOs) obtained from spent materials or pruning waste of four plant species: Zingiber officinale Roscoe used in the juicing industry, Pistacia vera L. var. Bronte used in the food industry, discarded material of industrial hemp (Cannabis sativa L. var. Futura 75), and pruning waste from Cupressus sempervirens L. The phytochemical profile of the EOs was evaluated by gas chromatographic flame ionization detection (GC-FID) and GC-MS analyses, which highlighted the presence of several compounds with a wide range of biological activities. Among them, application possibilities in agriculture were evaluated by studying the phytotoxic activity in vitro against germination and initial radical growth of several seeds such as Raphanus sativus L., Lepidium sativum L., Lactuca sativa L., Solanum lycopersicum L., Lolium multiflorum Lam., and Portulaca oleracea L.

Piper Species: A Comprehensive Review on Their Phytochemistry, Biological Activities and Applications.

Piper species are aromatic plants used as spices in the kitchen, but their secondary metabolites have also shown biological effects on human health. These plants are rich in essential oils, which can be found in their fruits, seeds, leaves, branches, roots and stems. Some Piper species have simple chemical profiles, while others, such as Piper nigrum, Piper betle, and Piper auritum, contain very diverse suites of secondary metabolites. In traditional medicine, Piper species have been used worldwide to treat several diseases such as urological problems, skin, liver and stomach ailments, for wound healing, and as antipyretic and anti-inflammatory agents. In addition, Piper species could be used as natural antioxidants and antimicrobial agents in food preservation. The phytochemicals and essential oils of Piper species have shown strong antioxidant activity, in comparison with synthetic antioxidants, and demonstrated antibacterial and antifungal activities against human pathogens. Moreover, Piper species possess therapeutic and preventive potential against several chronic disorders. Among the functional properties of Piper plants/extracts/active components the antiproliferative, anti-inflammatory, and neuropharmacological activities of the extracts and extract-derived bioactive constituents are thought to be key effects for the protection against chronic conditions, based on preclinical in vitro and in vivo studies, besides clinical studies. Habitats and cultivation of Piper species are also covered in this review. In this current work, available literature of chemical constituents of the essential oils Piper plants, their use in traditional medicine, their applications as a food preservative, their antiparasitic activities and other important biological activities are reviewed.

Tagetes spp. Essential Oils and Other Extracts: Chemical Characterization and Biological Activity.

Tagetes (marigold) is native to America, and its cultivation currently extends to other countries in Africa, Asia, and Europe. Many species of this genus, such as T. minuta, T. erecta, T. patula, and T. tenuifolia, are cultivated as ornamental plants and studied for their medicinal properties on the basis of their use in folk medicine. Different parts of the Tagetes species are used as remedies to treat various health problems, including dental, stomach, intestinal, emotional, and nervous disorders, as well as muscular pain, across the world. Furthermore, these plants are studied in the field of agriculture for their fungicidal, bactericidal, and insecticidal activities. The phytochemical composition of the extracts of different Tagetes species parts are reported in this work. These compounds exhibit antioxidant, antiinflammatory, and enzyme inhibitory properties. Cultivation and the factors affecting the chemical composition of Tagetes species are also covered. In the current work, available literature on Tagetes species in traditional medicine, their application as a food preservative, and their antimicrobial activities are reviewed.

Biological Activities of Essential Oils: From Plant Chemoecology to Traditional Healing Systems.

Essential oils are complex mixtures of hydrocarbons and their oxygenated derivatives arising from two different isoprenoid pathways. Essential oils are produced by glandular trichomes and other secretory structures, specialized secretory tissues mainly diffused onto the surface of plant organs, particularly flowers and leaves, thus exerting a pivotal ecological role in plant. In addition, essential oils have been used, since ancient times, in many different traditional healing systems all over the world, because of their biological activities. Many preclinical studies have documented antimicrobial, antioxidant, anti-inflammatory and anticancer activities of essential oils in a number of cell and animal models, also elucidating their mechanism of action and pharmacological targets, though the paucity of in human studies limits the potential of essential oils as effective and safe phytotherapeutic agents. More well-designed clinical trials are needed in order to ascertain the real efficacy and safety of these plant products.

Functional foods with digestion-enhancing properties.

On analyzing the traditional societies' plant lore by treatment and plant categories, one cannot but notice the greater weight given to treatment of digestive disturbances and ailments compared to modern Western pharmacopoeias, and the blurred boundaries between medicines and foods, in contrast to the clear-cut distinction made in contemporary industrialized societies. Hence, there is an interest in exploring the issue of multifunctional food and traditional ingredients with digestive properties. In this paper, I examine the coevolutionary foundations for digestive activities, the problems and ambiguities that emerge in the analysis of traditional data, and the possible biological mechanisms underlying the actions of bitter, aromatic and pungent compounds. After these premises, this paper presents a short review of those plants with a significant body of research supporting the claims that they have a digestive action, with particular emphasis on clinical data. The plants that have a substantial body of data in support of their digestion-enhancing activities mainly belong to one of three groups: bitter, aromatic and pungent plants. Amongst the most important we can find ginger, peppermint, aniseed and fennel, citrus fruits, dandelion and artichoke, melissa and chamomile, but many more have a significant body of experimental data available.