The role of flavor and fragrance chemicals in TRPA1 (transient receptor potential cation channel, member A1) activity associated with allergies

Acute and Persistent Cardiovascular Effects of Menthol E-Cigarettes in Mice

BACKGROUND

Although e-cigarettes provide an alternative to conventional smoking, the cardiovascular impacts of e-cigarette use are unresolved. The popularity of menthol e-cigarettes has surged recently and may escalate further with bans on combustible menthol cigarettes and e-cigarette flavors other than menthol and tobacco. Despite recent evidence in mice that menthol e-cigarettes acutely induce cardiac arrhythmias, the impacts of repeated menthol e-cigarette use on cardiovascular function and the cardiac proteome remain unclear. We therefore investigated the acute and persistent cardiovascular effects of menthol e-cigarettes in a mouse model.

METHODS AND RESULTS

Adult C57BL/6J mice with ECG and blood pressure radiotransmitters were exposed to e-cigarette aerosols (180-270 puffs/day; n=4-8/group). One-day exposures to nicotine-containing e-cigarette aerosols depressed heart rate variability regardless of flavor, but menthol e-cigarette aerosols uniquely increased heart rate and urine epinephrine and elicited spontaneous ventricular premature beats. Menthol e-cigarette aerosols consistently increased blood pressure acutely, and this effect recurred throughout the 20-day regimen. Pretreatment with atenolol abolished e-cigarette-induced arrhythmias, suggesting the involvement of β1-adrenoceptors. After 4 weeks of exposure to JUUL Menthol aerosol, mice had basal sinus bradycardia that persisted up to 3 weeks after exposure cessation. After cessation, e-cigarette-exposed mice also exhibited an altered chronotropic response to restraint stress and prolonged ventricular repolarization (corrected QT interval). Integrated proteomic and phosphoproteomic analysis of cardiac tissue harvested from mice exposed to menthol e-cigarette aerosols for 5 and 20 days revealed molecular signatures of dilated and arrhythmogenic cardiomyopathy.

CONCLUSIONS

Exposure to menthol e-cigarette aerosols induces persistent cardiovascular autonomic imbalance in vivo. These findings raise the possibility of similar effects in humans using mentholated e-cigarettes.

Managing a Burning Face: Clinical Manifestations and Therapeutic Approaches for Neurogenic Rosacea

Rosacea is a common chronic inflammatory condition primarily affecting middle-aged women. It presents with flushing, erythema, telangiectasia, papules, pustules, phymatous changes, and ocular involvement. Although typically grouped into four subtypes-erythematotelangiectatic, papulopustular, ocular, and phymatous-overlapping features often favor a phenotypic diagnostic approach. Neurogenic rosacea (NR) has emerged as a distinct subgroup featuring distinguishing features such as peripheral facial erythema, severe burning and stinging sensations, and resistance to standard rosacea therapies. Recent insights into the pathophysiology of NR propose neural dysregulation as the main driver of the condition. Specifically, the activation of TRP channels at cutaneous sensory nerve endings in the dermis triggers the release of vasoactive peptides, driving neuroinflammation and resulting in burning and stinging. Additionally, there is a marked association with neuropsychiatric comorbidities, which would further mediate the pathogenesis of the condition. In line with this pathophysiological model, NR often fails to respond to conventional rosacea treatments. Instead, patients benefit more from antidepressants and neuroleptic agents that help modulate neuronal activity and alleviate symptoms. This review explores and summarizes the scientific evidence regarding the new insights on disease pathogenesis, clinical manifestations, and proposed treatments for NR.

Anesthetic- and Analgesic-Related Drugs Modulating Both Voltage-Gated Na+ and TRP Channels

Nociceptive information is transmitted by action potentials (APs) through primary afferent neurons from the periphery to the central nervous system. Voltage-gated Na+ channels are involved in this AP production, while transient receptor potential (TRP) channels, which are non-selective cation channels, are involved in receiving and transmitting nociceptive stimuli in the peripheral and central terminals of the primary afferent neurons. Peripheral terminal TRP vanilloid-1 (TRPV1), ankylin-1 (TRPA1) and melastatin-8 (TRPM8) activation produces APs, while central terminal TRP activation enhances the spontaneous release of L-glutamate from the terminal to spinal cord and brain stem lamina II neurons that play a pivotal role in modulating nociceptive transmission. There is much evidence demonstrating that chemical compounds involved in Na+ channel (or nerve AP conduction) inhibition modify TRP channel functions. Among these compounds are local anesthetics, anti-epileptics, α2-adrenoceptor agonists, antidepressants (all of which are used as analgesic adjuvants), general anesthetics, opioids, non-steroidal anti-inflammatory drugs and plant-derived compounds, many of which are involved in antinociception. This review mentions the modulation of Na+ channels and TRP channels including TRPV1, TRPA1 and TRPM8, both of which modulations are produced by pain-related compounds.

The dual role of TRPV1 in peripheral neuropathic pain: pain switches caused by its sensitization or desensitization

The transient receptor potential vanilloid 1 (TRPV1) channel plays a dual role in peripheral neuropathic pain (NeuP) by acting as a "pain switch" through its sensitization and desensitization. Hyperalgesia, commonly resulting from tissue injury or inflammation, involves the sensitization of TRPV1 channels, which modulates sensory transmission from primary afferent nociceptors to spinal dorsal horn neurons. In chemotherapy-induced peripheral neuropathy (CIPN), TRPV1 is implicated in neuropathic pain mechanisms due to its interaction with ion channels, neurotransmitter signaling, and oxidative stress. Sensitization of TRPV1 in dorsal root ganglion neurons contributes to CIPN development, and inhibition of TRPV1 channels can reduce chemotherapy-induced mechanical hypersensitivity. In diabetic peripheral neuropathy (DPN), TRPV1 is involved in pain modulation through pathways including reactive oxygen species and cytokine production. TRPV1's interaction with TRPA1 channels further influences chronic pain onset and progression. Therapeutically, capsaicin, a TRPV1 agonist, can induce analgesia through receptor desensitization, while TRPV1 antagonists and siRNA targeting TRPV1 show promise in preclinical studies. Cannabinoid modulation of TRPV1 provides another potential pathway for alleviating neuropathic pain. This review summarizes recent preclinical research on TRPV1 in association with peripheral NeuP.

Advances and perspectives on pharmacological activities and mechanisms of the monoterpene borneol

BACKGROUND

Borneol, a highly lipid-soluble bicyclic terpene mainly extracted from plants, is representative of monoterpenoids. Modern medicine has established that borneol exhibits a range of pharmacological activities and used in the treatment of many diseases, particularly Cardio-cerebrovascular diseases (CVDs). The crucial role in enhancing drug delivery and improving bioavailability has attracted much attention. In addition, borneol is also widely utilized in food, daily chemicals, fragrances, and flavors industries.

PURPOSE

This review systematically summarized the sources, pharmacological activities and mechanisms, clinical trial, pharmacokinetics, toxicity, and application of borneol. In addition, this review describes the pharmacological effects of borneol ester and the combination of borneol with nanomaterial. This review will provide a valuable resource for those pursuing researches on borneol inspiring the pharmacological applications in the medicine, food and daily chemical products, and developing of new drugs containing borneol or its derivatives.

METHODS

This review searched the keywords ("borneol" or "bornyl esters") and ("pharmacology" or "Traditional Chinese medicine" or "Cardio-cerebrovascular diseases" or "blood-brain barrier" or "ischemic stroke" or "nanomaterials" or "neurodegenerative diseases" or "diabetes" or "toxicity") in Web of Science, PubMed, Google Scholar and China National Knowledge Infrastructure (CNKI) from January 1990 to May 2024. The search was limited to articles published in English and Chinese.

RESULTS

Borneol exhibits extensive pharmacological activities including anti-inflammatory effects, analgesia, antioxidation, and has the property of crossing biological barriers and treating CVDs. The intrinsic molecular mechanisms are involved in multiple components, such as regulation of various key factors (including Tumor necrosis factor-α, Nuclear factor kappa-B, Interleukin-1β, Malondialdehyde), inhibiting transporter protein function, regulating biochemical levels, and altering physical structural changes. In addition, this review describes the pharmacological effects of borneol ester and the combination of borneol with nanomaterial.

CONCLUSION

The pharmacological properties and applications of borneol are promising, including anti-inflammatory, analgesic, antimicrobial, and antioxidant properties, as well as enhancing drug delivery and treating CVDs. However, its clinical application is hindered by the limited research on safety, efficacy, and pharmacokinetics. Therefore, this review systemically summarized the advances on pharmacological activities and mechanisms of the borneol. Standardized clinical trials and exploration of synergistic effects with other drugs were also are outlined.

Design of Novel TRPA1 Agonists Based on Structure of Natural Vasodilator Carvacrol-In Vitro and In Silico Studies

Considering the escalating global prevalence and the huge therapeutic demand for the treatment of hypertension, there is a persistent need to identify novel target sites for vasodilator action. This study aimed to investigate the role of TRPA1 channels in carvacrol-induced vasodilation and to design novel compounds based on carvacrol structure with improved activities. In an isolated tissue bath experiment, it was shown that 1 µM of the selective TRPA1 antagonist A967079 significantly (p < 0.001) reduced vasodilation induced by 3 mM of carvacrol. A reliable 3D-QSAR model with good statistical parameters was created (R2 = 0.83; Q2 = 0.59 and Rpred2 = 0.84) using 29 TRPA1 agonists. Obtained results from this model were used for the design of novel TRPA1 activators, and to predict their activity against TRPA1. Predicted pEC50 activities of these molecules range between 4.996 to 5.235 compared to experimental pEC50 of 4.77 for carvacrol. Molecular docking studies showed that designed molecules interact with similar amino acid residues of the TRPA1 channel as carvacrol, with eight compounds showing lower binding energies. In conclusion, carvacrol-induced vasodilation is partly mediated by the activation of TRPA1 channels. Combining different in silico approaches pointed out that the molecule D27 (2-[2-(hydroxymethyl)-4-methylphenyl]acetamide) is the best candidate for further synthesis and experimental evaluation in in vitro conditions.

Exposure limits for indoor volatile substances concerning the general population: The role of population-based differences in sensory irritation of the eyes and airways for assessment factors

Assessment factors (AFs) are essential in the derivation of occupational exposure limits (OELs) and indoor air quality guidelines. The factors shall accommodate differences in sensitivity between subgroups, i.e., workers, healthy and sick people, and occupational exposure versus life-long exposure for the general population. Derivation of AFs itself is based on empirical knowledge from human and animal exposure studies with immanent uncertainty in the empirical evidence due to knowledge gaps and experimental reliability. Sensory irritation in the eyes and airways constitute about 30-40% of OELs and is an abundant symptom in non-industrial buildings characterizing the indoor air quality and general health. Intraspecies differences between subgroups of the general population should be quantified for the proposal of more 'empirical' based AFs. In this review, we focus on sensitivity differences in sensory irritation about gender, age, health status, and vulnerability in people, based solely on human exposure studies. Females are more sensitive to sensory irritation than males for few volatile substances. Older people appear less sensitive than younger ones. However, impaired defense mechanisms may increase vulnerability in the long term. Empirical evidence of sensory irritation in children is rare and limited to children down to the age of six years. Studies of the nervous system in children compared to adults suggest a higher sensitivity in children; however, some defense mechanisms are more efficient in children than in adults. Usually, exposure studies are performed with healthy subjects. Exposure studies with sick people are not representative due to the deselection of subjects with moderate or severe eye or airway diseases, which likely underestimates the sensitivity of the group of people with diseases. Psychological characterization like personality factors shows that concentrations of volatile substances far below their sensory irritation thresholds may influence the sensitivity, in part biased by odor perception. Thus, the protection of people with extreme personality traits is not feasible by an AF and other mitigation strategies are required. The available empirical evidence comprising age, lifestyle, and health supports an AF of not greater than up to 2 for sensory irritation. Further, general AFs are discouraged for derivation, rather substance-specific derivation of AFs is recommended based on the risk assessment of empirical data, deposition in the airways depending on the substance's water solubility and compensating for knowledge and experimental gaps. Modeling of sensory irritation would be a better 'empirical' starting point for derivation of AFs for children, older, and sick people, as human exposure studies are not possible (due to ethical reasons) or not generalizable (due to self-selection). Dedicated AFs may be derived for environments where dry air, high room temperature, and visually demanding tasks aggravate the eyes or airways than for places in which the workload is balanced, while indoor playgrounds might need other AFs due to physical workload and affected groups of the general population.

Mono-2-ethylhexylphthalate (MEHP) is a potent agonist of human TRPA1 channel

Phthalates are extensively used as plasticizers in diverse consumer care products but have been reported to cause adverse health effects in humans. A commonly used phthalate, di-2-ethylhexylphthalate (DEHP) causes developmental and reproductive toxicities in humans, but the associated molecular mechanisms are not fully understood. Mono-2-ethylhexylphthalate (MEHP), a hydrolytic product of DEHP generated by cellular esterases, is proposed to be the active toxicant. We conducted a screen for sensory irritants among compounds used in consumer care using an assay for human Transient Receptor Potential A1 (hTRPA1). We have identified MEHP as a potent agonist of hTRPA1. MEHP-induced hTRPA1 activation was blocked by the TRPA1 inhibitor A-967079. Patch clamp assays revealed that MEHP induced inward currents in cells expressing hTRPA1. In addition, the N855S mutation in hTRPA1 associated with familial episodic pain syndrome decreased MEHP-induced hTRPA1 activation. In summary, we report that MEHP is a potent agonist of hTRPA1 which generates new possible mechanisms for toxic effects of phthalates in humans.

Sulforaphane decreases serum selenoprotein P levels through enhancement of lysosomal degradation independent of Nrf2

Selenoprotein P (SeP) is a major selenoprotein in serum predominantly produced in the liver. Excess SeP impairs insulin secretion from the pancreas and insulin sensitivity in skeletal muscle, thus inhibition of SeP could be a therapeutic strategy for type 2 diabetes. In this study, we examine the effect of sulforaphane (SFN), a phytochemical of broccoli sprouts and an Nrf2 activator, on SeP expression in vitro and in vivo. Treatment of HepG2 cells with SFN decreases inter- and intra-cellular SeP levels. SFN enhances lysosomal acidification and expression of V-ATPase, and inhibition of this process cancels the decrease of SeP by SFN. SFN activates Nrf2 in the cells, while Nrf2 siRNA does not affect the decrease of SeP by SFN or lysosomal acidification. These results indicate that SFN decreases SeP by enhancing lysosomal degradation, independent of Nrf2. Injection of SFN to mice results in induction of cathepsin and a decrease of SeP in serum. The findings from this study are expected to contribute to developing SeP inhibitors in the future, thereby contributing to treating and preventing diseases related to increased SeP.

Allyl isothiocyanate mitigates airway inflammation and constriction in a house dust mite-induced allergic asthma model via upregulation of tight junction proteins and the TRPA1 modulation

Asthma is a chronic inflammatory disease that has been associated with insufficient vegetable intake. Allyl Isothiocyanate (AITC) is a natural isothiocyanate found in cruciferous plants with anti-inflammatory and antioxidant abilities. Our study aimed to investigate the potential effect of AITC on tracheal constriction in a house dust mite (HDM)-induced asthma animal model, and explore the underlying mechanisms. To investigate the effects of AITC on HDM-induced allergic asthma model, established by intranasally administering extracts of HDM and AITC or DEX was given orally for four weeks. Flexivent SCIREQ, H&E staining, ELISA were employed to evaluate the lung function and the cytokine secretion. Possible mechanisms were determined by Western blot. Rat tracheae contraction was measured by Labscribe. We utilized lung epithelial cells (BEAS-2B) to assess the adhesion response to the combination of inflammatory factors TNF-α and IL-4. The results of the study showed that AITC significantly reduced tracheal constriction in ex vivo experiments and improved lung function in in vivo experiments compared to HDM-induced mice. Additionally, AITC decreased cytokine secretion, inflammatory cell infiltration in the lung, and constriction-related proteins expression in both lung and tracheae. Moreover, AITC increased tight junction-related protein expression in lung tissues. In vitro experiments showed that AITC had a protective effect through TRPA1 channel without affecting cell viability. Our results demonstrate that AITC has potential anti-asthma effects in HDM-induced asthma models by alleviating airway inflammation and airway constriction through increasing tight junction-related protein expression and suppressing Ca2+ signaling. These findings suggest that AITC may be a beneficial adjuvant therapy in asthma treatment.

Antimony Compounds Associate with Atopic Dermatitis and Influence Models of Itch and Dysbiosis

Compared to the myriad of known triggers for rhinitis and asthma, environmental exposure research for atopic dermatitis (AD) is not well established. We recently reported that an untargeted search of U.S. Environmental Protection Agency (EPA) databases versus AD rates by United States (U.S.) postal codes revealed that isocyanates, such as toluene diisocyanate (TDI), are the pollutant class with the strongest spatiotemporal and epidemiologic association with AD. We further demonstrated that (di)isocyanates disrupt ceramide-family lipid production in commensal bacteria and activate the thermo-itch host receptor TRPA1. In this report, we reanalyzed regions of the U.S. with low levels of diisocyanate pollution to assess if a different chemical class may contribute. We identified antimony compounds as the top associated pollutant in such regions. Exposure to antimony compounds would be expected from brake dust in high-traffic areas, smelting plants, bottled water, and dust from aerosolized soil. Like TDI, antimony inhibited ceramide-family lipid production in Roseomonas mucosa and activated TRPA1 in human neurons. While further epidemiologic research will be needed to directly evaluate antimony exposure with surrounding AD prevalence and severity, these data suggest that compounds which are epidemiologically associated with AD, inhibit commensal lipid production, and activate TRPA1 may be causally related to AD pathogenesis.

Olfactory Function and Olfactory Disorders

The sense of smell is important. This became especially clear to patients with infection-related olfactory loss during the SARS-CoV-2 pandemic. We react, for example, to the body odors of other humans. The sense of smell warns us of danger, and it allows us to perceive flavors when eating and drinking. In essence, this means quality of life. Therefore, anosmia must be taken seriously. Although olfactory receptor neurons are characterized by regenerative capacity, anosmia is relatively common with about 5 % of anosmic people in the general population. Olfactory disorders are classified according to their causes (e. g., infections of the upper respiratory tract, traumatic brain injury, chronic rhinosinusitis, age) with the resulting different therapeutic options and prognoses. Thorough history taking is therefore important. A wide variety of tools are available for diagnosis, ranging from short screening tests and detailed multidimensional test procedures to electrophysiological and imaging methods. Thus, quantitative olfactory disorders are easily assessable and traceable. For qualitative olfactory disorders such as parosmia, however, no objectifying diagnostic procedures are currently available. Therapeutic options for olfactory disorders are limited. Nevertheless, there are effective options consisting of olfactory training as well as various additive drug therapies. The consultation and the competent discussion with the patients are of major importance.

Neuropathic pain: Mechanisms and therapeutic strategies

The physiopathology and neurotransmission of pain are of an owe inspiring complexity. Our ability to satisfactorily suppress neuropathic or other forms of chronic pain is limited. The number of pharmacodynamically distinct and clinically available medications is low and the successes achieved modest. Pain Medicine practitioners are confronted with the ethical dichotomy imposed by Hippocrates: On one hand the mandate of primum non nocere, on the other hand, the promise of heavenly joys if successful divinum est opus sedare dolorem. We briefly summarize the concepts associated with nociceptive pain from nociceptive input (afferents from periphery), modulatory output [descending noradrenergic (NE) and serotoninergic (5-HT) fibers] to local control. The local control is comprised of the "inflammatory soup" at the site of pain origin and synaptic relay stations, with an ATP-rich environment promoting inflammation and nociception while an adenosine-rich environment having the opposite effect. Subsequently, we address the transition from nociceptor pain to neuropathic pain (independent of nociceptor activation) and the process of sensitization and pain chronification (transient pain progressing into persistent pain). Having sketched a model of pain perception and processing we attempt to identify the sites and modes of action of clinically available drugs used in chronic pain treatment, focusing on adjuvant (co-analgesic) medication.

Exposure to isocyanates predicts atopic dermatitis prevalence and disrupts therapeutic pathways in commensal bacteria

Atopic dermatitis (AD) is a chronic inflammatory skin condition increasing in industrial nations at a pace that suggests environmental drivers. We hypothesize that the dysbiosis associated with AD may signal microbial adaptations to modern pollutants. Having previously modeled the benefits of health-associated Roseomonas mucosa, we now show that R. mucosa fixes nitrogen in the production of protective glycerolipids and their ceramide by-products. Screening EPA databases against the clinical visit rates identified diisocyanates as the strongest predictor of AD. Diisocyanates disrupted the production of beneficial lipids and therapeutic modeling for isolates of R. mucosa as well as commensal Staphylococcus. Last, while topical R. mucosa failed to meet commercial end points in a placebo-controlled trial, the subgroup who completed the full protocol demonstrated sustained, clinically modest, but statistically significant clinical improvements that differed by study site diisocyanate levels. Therefore, diisocyanates show temporospatial and epidemiological association with AD while also inducing eczematous dysbiosis.

Diisocyanates influence models of atopic dermatitis through direct activation of TRPA1

We recently used EPA databases to identify that isocyanates, most notably toluene diisocyanate (TDI), were the pollutant class with the strongest spatiotemporal and epidemiologic association with atopic dermatitis (AD). Our findings demonstrated that isocyanates like TDI disrupted lipid homeostasis and modeled benefit in commensal bacteria like Roseomonas mucosa through disrupting nitrogen fixation. However, TDI has also been established to activate transient receptor potential ankyrin 1 (TRPA1) in mice and thus could directly contribute to AD through induction of itch, rash, and psychological stress. Using cell culture and mouse models, we now demonstrate that TDI induced skin inflammation in mice as well as calcium influx in human neurons; each of these findings were dependent on TRPA1. Furthermore, TRPA1 blockade synergized with R. mucosa treatment in mice to improve TDI-independent models of AD. Finally, we show that the cellular effects of TRPA1 are related to shifting the balance of the tyrosine metabolites epinephrine and dopamine. This work provides added insight into the potential role, and therapeutic potential, or TRPA1 in the pathogenesis of AD.

TRP channels and monoterpenes: Past and current leads on analgesic properties

The activation of the transient receptor potential (TRP) channels expressed by sensory neurons is essential to the transduction of thermal and mechanical sensory information. In the setting of chronic inflammatory conditions, the activation of the melastatin family member 8 (TRPM8), the TRP vanilloid 1 (TRPV1), and the TRP ankyrin 1 (TRPA1) is correlated with pain hypersensitivity reactions. Monoterpenes, among which pulegone and menthol, a major class of phytocompounds present in essential oils of medicinal plants, are known modulators of those TRP channels activity. In the present review, we correlate the monoterpene content of plants with their historical therapeutic properties. We then describe how monoterpenes exert their anti-inflammatory and antihyperalgesia effects through modulation of TRP channels activity. Finally, we discuss the importance and the potential of characterizing new plant extracts and reassessing studied plant extracts for the development of ethnopharmacology-based innovative treatments for chronic pain. This review suggests that monoterpene solutions, based on composition from traditional healing herbs, offer an interesting avenue for the development of new phytotherapeutic treatments to alleviate chronic inflammatory pain conditions.

Treatment of Gastrointestinal Disorders-Plants and Potential Mechanisms of Action of Their Constituents

The worldwide prevalence of gastrointestinal diseases is about 40%, with standard pharmacotherapy being long-lasting and economically challenging. Of the dozens of diseases listed by the Rome IV Foundation criteria, for five of them (heartburn, dyspepsia, nausea and vomiting disorder, constipation, and diarrhoea), treatment with herbals is an official alternative, legislatively supported by the European Medicines Agency (EMA). However, for most plants, the Directive does not require a description of the mechanisms of action, which should be related to the therapeutic effect of the European plant in question. This review article, therefore, summarizes the basic pharmacological knowledge of synthetic drugs used in selected functional gastrointestinal disorders (FGIDs) and correlates them with the constituents of medicinal plants. Therefore, the information presented here is intended as a starting point to support the claim that both empirical folk medicine and current and decades-old treatments with official herbal remedies have a rational basis in modern pharmacology.

Cannabinoids interaction with transient receptor potential family and implications in the treatment of rosacea

With the recent interest in medical marijuana, research into cannabinoids is regaining wider attention. Cannabinoids are collectively a group of active compounds that can be produced by animals (endocannabinoids), plants (phytocannabinoids), or synthetically. By acting on a number of different receptors like cannabinoids receptors and transient receptor potential ion channel family, cannabinoids are known to modulate cutaneous inflammation, pain, and itch. Rosacea is a highly prevalent disease and can be associated with a significant degree of morbidity associated with its symptom. Transient receptor potential ion channels are known to be triggered in rosacea and may underlie a portion of rosacea's pathophysiology. This article aims to detail the transient receptor potential channel pathways in rosacea and the known effects of cannabinoids on these pathways and further discussing the potential role of cannabinoids in treating rosacea.

Remedia Sternutatoria over the Centuries: TRP Mediation

Sneezing (sternutatio) is a poorly understood polysynaptic physiologic reflex phenomenon. Sneezing has exerted a strange fascination on humans throughout history, and induced sneezing was widely used by physicians for therapeutic purposes, on the assumption that sneezing eliminates noxious factors from the body, mainly from the head. The present contribution examines the various mixtures used for inducing sneezes (remedia sternutatoria) over the centuries. The majority of the constituents of the sneeze-inducing remedies are modulators of transient receptor potential (TRP) channels. The TRP channel superfamily consists of large heterogeneous groups of channels that play numerous physiological roles such as thermosensation, chemosensation, osmosensation and mechanosensation. Sneezing is associated with the activation of the wasabi receptor, (TRPA1), typical ligand is allyl isothiocyanate and the hot chili pepper receptor, (TRPV1), typical agonist is capsaicin, in the vagal sensory nerve terminals, activated by noxious stimulants.

Allicin, the Odor of Freshly Crushed Garlic: A Review of Recent Progress in Understanding Allicin's Effects on Cells

The volatile organic sulfur compound allicin (diallyl thiosulfinate) is produced as a defense substance when garlic (Allium sativum) tissues are damaged, for example by the activities of pathogens or pests. Allicin gives crushed garlic its characteristic odor, is membrane permeable and readily taken up by exposed cells. It is a reactive thiol-trapping sulfur compound that S-thioallylates accessible cysteine residues in proteins and low molecular weight thiols including the cellular redox buffer glutathione (GSH) in eukaryotes and Gram-negative bacteria, as well as bacillithiol (BSH) in Gram-positive firmicutes. Allicin shows dose-dependent antimicrobial activity. At higher doses in eukaryotes allicin can induce apoptosis or necrosis, whereas lower, biocompatible amounts can modulate the activity of redox-sensitive proteins and affect cellular signaling. This review summarizes our current knowledge of how bacterial and eukaryotic cells are specifically affected by, and respond to, allicin.

Development of antibacterial nanofibrous wound dressing and conceptual reaction mechanism to deactivate the viral protein by Nigella sativa extract

Nigella sativa (N. sativa) is extensively used as medicinal plant all over the world. It has the potential properties as the antiviral and antibacterial application. Its seed contain thymoquinone (TQ), thymohydroquinone (THQ), thymol (THY), p-cymene as major and other minor components. TQ and THQ exhibit broad spectrum of antimicrobial properties against the activity of bacteria, viruses, parasites, schistosoma and fungi. This work provides credence to the fabrication of antibacterial nanofibrous membrane by electrospinning machine from N. sativa extract with polyvinyl alcohol (PVA) solution for wound dressing. The morphology of the developed membrane is also characterized using scanning electron microscope. Fourier transform infrared spectroscopy (FTIR) data has been showed that the functional groups of N. sativa are present in the prepared PVA-N. sativa nanofibrous membrane and its antibacterial activity was investigated. The disk diffusion method has been used to evaluate the antibacterial activity of PVA-N. sativa nanofibrous membrane against Staphylococcus aureus (S. aureus) bacteria and the inhibition zone with a value of 10 mm is formed. Considering the inherent properties of N. sativa, a conceptual reaction mechanism has been proposed to deactivate the viral proteins by the action of TQ and THQ.

Essential Oils from Monarda fistulosa: Chemical Composition and Activation of Transient Receptor Potential A1 (TRPA1) Channels

Little is known about the pharmacological activity of Monarda fistulosa L. essential oils. To address this issue, we isolated essential oils from the flowers and leaves of M. fistulosa and analyzed their chemical composition. We also analyzed the pharmacological effects of M. fistulosa essential oils on transient receptor potential (TRP) channel activity, as these channels are known targets of various essential oil constituents. Flower (MEOFl) and leaf (MEOLv) essential oils were comprised mainly of monoterpenes (43.1% and 21.1%) and oxygenated monoterpenes (54.8% and 77.7%), respectively, with a high abundance of monoterpene hydrocarbons, including p-cymene, γ-terpinene, α-terpinene, and α-thujene. Major oxygenated monoterpenes of MEOFl and MEOLv included carvacrol and thymol. Both MEOFl and MEOLv stimulated a transient increase in intracellular free Ca2+ concentration ([Ca2+]i) in TRPA1 but not in TRPV1 or TRPV4-transfected cells, with MEOLv being much more effective than MEOFl. Furthermore, the pure monoterpenes carvacrol, thymol, and β-myrcene activated TRPA1 but not the TRPV1 or TRPV4 channels, suggesting that these compounds represented the TRPA1-activating components of M. fistulosa essential oils. The transient increase in [Ca2+]i induced by MEOFl/MEOLv, carvacrol, β-myrcene, and thymol in TRPA1-transfected cells was blocked by a selective TRPA1 antagonist, HC-030031. Although carvacrol and thymol have been reported previously to activate the TRPA1 channels, this is the first report to show that β-myrcene is also a TRPA1 channel agonist. Finally, molecular modeling studies showed a substantial similarity between the docking poses of carvacrol, thymol, and β-myrcene in the binding site of human TRPA1. Thus, our results provide a cellular and molecular basis to explain at least part of the therapeutic properties of these essential oils, laying the foundation for prospective pharmacological studies involving TRP ion channels.

Effects of Thymus vulgaris L., Cinnamomum verum J.Presl and Cymbopogon nardus (L.) Rendle Essential Oils in the Endotoxin-induced Acute Airway Inflammation Mouse Model

Thyme (TO), cinnamon (CO), and Ceylon type lemongrass (LO) essential oils (EOs) are commonly used for inhalation. However, their effects and mechanisms on inflammatory processes are not well-documented, and the number of in vivo data that would be important to determine their potential benefits or risks is low. Therefore, we analyzed the chemical composition and investigated the activity of TO, CO, and LO on airway functions and inflammatory parameters in an acute pneumonitis mouse model. The components of commercially available EOs were measured by gas chromatography-mass spectrometry. Airway inflammation was induced by intratracheal endotoxin administration in mice. EOs were inhaled during the experiments. Airway function and hyperresponsiveness were determined by unrestrained whole-body plethysmography on conscious animals. Myeloperoxidase (MPO) activity was measured by spectrophotometry from lung tissue homogenates, from which semiquantitative histopathological scores were assessed. The main components of TO, CO, and LO were thymol, cinnamaldehyde, and citronellal, respectively. We provide here the first evidence that TO and CO reduce inflammatory airway hyperresponsiveness and certain cellular inflammatory parameters, so they can potentially be considered as adjuvant treatments in respiratory inflammatory conditions. In contrast, Ceylon type LO inhalation might have an irritant effect (e.g., increased airway hyperresponsiveness and MPO activity) on the inflamed airways, and therefore should be avoided.

The neuro-immune interaction in airway inflammation through TRPA1 expression in CD4+ T cells of asthmatic mice

Asthma is an inflammatory disorder of the airways dominated by a Th2-type pattern. Recently, an emerging interest arises whether transient receptor potential ankyrin 1 (TRPA1) plays a potential role in the adaptive immune response. In this study, the role of TRPA1 in the development and exacerbation of asthma was explored. The classic OVA-induced asthma and OVA plus PM2.5-induced exacerbated asthma model were used. The CD4+ T cells were sorted from spleen in asthmatic and exacerbated asthmatic mice. In the BALB/c mice treated with OVA, the increased phenotype of asthma was obtained, accompanied by the high expression of TRPA1 in lung tissue and levels of IL-4, IL-13, NGF, PGD₂ in BAL. In contrast, genetic deletion or pharmacological inhibition of TRPA1 alleviated the phenotype of asthma. Similarly, in wild type (WT) C57BL/6 mice treated with OVA, the high expression of TRPA1 in lung tissues was obtained, and the levels of IL-4, IL-13, NGF, PGD₂ in BAL remarkably increased when compared with those in the TRPA1 deleted mice. Furthermore, high expression of TRPA1 was detected in CD4+ T cells of OVA-treated WT C57BL/6 mice. Additional detection in the asthmatic mice exacerbated by OVA plus PM2.5 also showed high TRPA1 expression in lung tissue and CD4+ T cells. All evidence confirmed that TRPA1 is essential for the development and exacerbation of asthma. More importantly, the expression of TRPA1 in CD4+ T cells of different asthmatic mice suggested that it might be involved in neuro-immune interactions in airway inflammation of asthmatic mice.

Differences in chemical composition of indoor air in rooms associated/not associated with building related symptoms

Building related health effects or symptoms (BRS), known also as sick-building syndrome (SBS), are a phenomenon that is not well understood. In this study, air samples from 51 rooms associated with BRS and 34 control rooms were collected on multi-sorbent tubes and analyzed by a non-target approach using comprehensive two-dimensional gas chromatography and high-resolution mass spectrometry techniques. The large amount of data gathered was analyzed using multivariate statistics (principle component analysis (PCA) and partial least squares (PLS)). This new analysis approach revealed that in rooms where people experienced BRS, petrochemicals and chemicals emitted from plastics were abundant, whereas in rooms where people did not experience BRS, flavor and fragrance compounds were abundant. Among the petrochemicals benzene and 2-butoxyethanol were found in higher levels in rooms where people experienced BRS. The levels of limonene were sometimes in the range of reported odor thresholds, and similarly 3-carene and beta-myrcene were found in higher concentrations in indoor air of rooms where people did not experience BRS. It cannot be ruled out that these compounds may have influenced the perceived air quality. However, the overall variability in air concentrations was large and it was not possible to accurately predict if the air in a particular room could cause BRS or not.

Myrcene and terpene regulation of TRPV1

Nociceptive Transient Receptor Potential channels such as TRPV1 are targets for treating pain. Both antagonism and agonism of TRP channels can promote analgesia, through inactivation and chronic desensitization. Since plant-derived mixtures of cannabinoids and the Cannabis component myrcene have been suggested as pain therapeutics, we screened terpenes found in Cannabis for activity at TRPV1. We used inducible expression of TRPV1 to examine TRPV1-dependency of terpene-induced calcium flux responses. Terpenes contribute differentially to calcium fluxes via TRPV1 induced by Cannabis-mimetic cannabinoid/terpenoid mixtures. Myrcene dominates the TRPV1-mediated calcium responses seen with terpenoid mixtures. Myrcene-induced calcium influx is inhibited by the TRPV1 inhibitor capsazepine and Myrcene elicits TRPV1 currents in the whole-cell patch-clamp configuration. TRPV1 currents are highly sensitive to internal calcium. When Myrcene currents are evoked, they are distinct from capsaicin responses on the basis of Imax and their lack of shift to a pore-dilated state. Myrcene pre-application and residency at TRPV1 appears to negatively impact subsequent responses to TRPV1 ligands such as Cannabidiol, indicating allosteric modulation and possible competition by Myrcene. Molecular docking studies suggest a non-covalent interaction site for Myrcene in TRPV1 and identifies key residues that form partially overlapping Myrcene and Cannabidiol binding sites. We identify several non-Cannabis plant-derived sources of Myrcene and other compounds targeting nociceptive TRPs using a data mining approach focused on analgesics suggested by non-Western Traditional Medical Systems. These data establish TRPV1 as a target of Myrcene and suggest the therapeutic potential of analgesic formulations containing Myrcene.

Assessment of Occupational Health Hazards Due to Particulate Matter Originated from Spices

Spices have been known for their various health activities; however, they also possess the allergic potential for the respiratory system and the skin as they are fine particulate matter. Persons involved in spice agriculture and food industries are at greater risk since they are exposed to a considerable amount of combustible dust, which may be the cause of fire and explosion and adversely affect the health. These workers may experience allergy, long-term and short-term respiratory issues including occupational asthma, dermatitis, etc. Some spices induce T cell-based inflammatory reaction upon contact recognition of the antigen. Antigen Presenting Cells (APC) on binding to the causative metabolite results in activation of macrophages by allergen cytokine interleukin (IL)-12 and tumor necrosis factor-beta (TNF). Cross-reactivity for protein allergens is another factor which seems to be a significant trigger for the stimulation of allergic reactions. Thus, it was imperative to perform a systematic review along with bioinformatics based representation of some evident allergens has been done to identify the overall conservation of epitopes. In the present manuscript, we have covered a multifold approach, i.e., to categorize the spice particles based on a clear understanding about nature, origin, mechanisms; to assess metabolic reactions of the particles after exposure as well as knowledge on the conditions of exposure along with associated potential health effects. Another aim of this study is to provide some suggestions to prevent and to control the exposure up to some extent.

Effects of TRPA1 activation and inhibition on TRPA1 and CGRP expression in dorsal root ganglion neurons

Transient receptor potential ankyrin 1 (TRPA1) is a key player in pain and neurogenic inflammation, and is localized in nociceptive primary sensory dorsal root ganglion (DRG) neurons. TRPA1 plays a major role in the transmission of nociceptive sensory signals. The generation of neurogenic inflammation appears to involve TRPA1-evoked release of calcitonin gene-related peptide (CGRP). However, it remains unknown whether TRPA1 or CGRP expression is affected by TRPA1 activation. Thus, in this study, we examined TRPA1 and CGRP expression in DRG neurons in vitro after treatment with the TRPA1 activator formaldehyde or the TRPA1 blocker menthol. In addition, we examined the role of extracellular signal-regulated protein kinase 1/2 (ERK1/2) in this process. DRG neurons in culture were exposed to formaldehyde, menthol, the ERK1/2 inhibitor PD98059 + formaldehyde, or PD98059 + menthol. After treatment, real-time polymerase chain reaction, western blot assay and double immunofluorescence labeling were performed to evaluate TRPA1 and CGRP expression in DRG neurons. Formaldehyde elevated mRNA and protein levels of TRPA1 and CGRP, as well as the proportion of TRPA1- and CGRP-positive neurons. In contrast, menthol reduced TRPA1 and CGRP expression. Furthermore, the effects of formaldehyde, but not menthol, on CGRP expression were blocked by pretreatment with PD98059. PD98059 pretreatment did not affect TRPA1 expression in the presence of formaldehyde or menthol.

Recent advances in understanding and managing rosacea

Rosacea is a common chronic inflammatory skin disease of the central facial skin and is of unknown origin. Currently, two classifications of rosacea exist that are based on either "preformed" clinical subtypes (erythematotelangiectatic, papulopustular, phymatous, and ocular) or patient-tailored analysis of the presented rosacea phenotype. Rosacea etiology and pathophysiology are poorly understood. However, recent findings indicate that genetic and environmental components can trigger rosacea initiation and aggravation by dysregulation of the innate and adaptive immune system. Trigger factors also lead to the release of various mediators such as keratinocytes (for example, cathelicidin, vascular endothelial growth factor, and endothelin-1), endothelial cells (nitric oxide), mast cells (cathelicidin and matrix metalloproteinases), macrophages (interferon-gamma, tumor necrosis factor, matrix metalloproteinases, and interleukin-26), and T helper type 1 (T _H1) and T _H17 cells. Additionally, trigger factors can directly communicate to the cutaneous nervous system and, by neurovascular and neuro-immune active neuropeptides, lead to the manifestation of rosacea lesions. Here, we aim to summarize the recent advances that preceded the new rosacea classification and address a symptom-based approach in the management of patients with rosacea.

TRP channels in cardiac and intestinal fibrosis

It is now widely accepted that advanced fibrosis underlies many chronic inflammatory disorders and is the main cause of morbidity and mortality of the modern world. The pathogenic mechanism of advanced fibrosis involves diverse and intricate interplays between numerous extracellular and intracellular signaling molecules, among which the non-trivial roles of a stress-responsive Ca²⁺/Na⁺-permeable cation channel superfamily, the transient receptor potential (TRP) protein, are receiving growing attention. Available evidence suggests that several TRP channels such as TRPC3, TRPC6, TRPV1, TRPV3, TRPV4, TRPA1, TRPM6 and TRPM7 may play central roles in the progression and/or prevention of fibroproliferative disorders in vital visceral organs such as lung, heart, liver, kidney, and bowel as well as brain, blood vessels and skin, and may contribute to both acute and chronic inflammatory processes involved therein. This short paper overviews the current knowledge accumulated in this rapidly growing field, with particular focus on cardiac and intestinal fibrosis, which are tightly associated with the pathogenesis of atrial fibrillation and inflammatory bowel diseases such as Crohn's disease.

The Transient Receptor Potential Ankyrin Type 1 Plays a Critical Role in Cortical Spreading Depression

The transient receptor potential ankyrin type-1 (TRPA1) channels have been proposed as a potential target for migraine therapy. Yet the role of cortical TRPA1 channels in migraine mechanism has not been fully understood. Cortical spreading depression (CSD) is known as an underlying cause of migraine aura. The aim of this study is to investigate if cortical TRPA1 activity is required for CSD genesis and propagation. A mouse brain slice CSD model with intrinsic optical imaging was applied for TRPA1 signaling pharmacology. The results showed that the TRPA1 agonist, umbellulone, facilitated the propagation of submaximal CSD. Correspondingly, an anti-TRPA1 antibody and two selective TRPA1 antagonists, A967079 and HC-030031, prolonged the CSD latency and reduced magnitude, indicating a reduced cortical susceptibility to CSD under TRPA1 deactivation. Furthermore, the TRPA1 agonist, allyl-isothiocyanate (AITC), reversed the suppression of CSD by HC-030031, but not by A967079. Interestingly, the inhibitory action of A967079 on CSD was reversed by exogenous calcitonin-gene-related peptide (CGRP). Consistent to TRPA1 deactivation, the prolonged CSD latency was observed by an anti-CGRP antibody in the mouse brain slice, which was reversed by exogenous CGRP. We conclude that cortical TRPA1 is critical in regulating cortical susceptibility to CSD, which involves CGRP. The data strongly suggest that deactivation of TRPA1 channels and blockade of CGRP would have therapeutic benefits in preventing migraine with aura.

Neuropharmacological Potential and Delivery Prospects of Thymoquinone for Neurological Disorders

Thymoquinone (TQ) is an active ingredient isolated from Nigella sativa and has various pharmacological activities, such as protection against oxidative stress, inflammation, and infections. In addition, it might be a potential neuropharmacological agent because it exhibits versatile potential for attenuating neurological impairments. It features greater beneficial effects in toxin-induced neuroinflammation and neurotoxicity. In various models of neurological disorders, it demonstrates emergent functions, including safeguarding various neurodegenerative diseases and other neurological diseases, such as stroke, schizophrenia, and epilepsy. TQ also has potential effects in trauma mediating and chemical-, radiation-, and drug-induced central nervous system injuries. Considering the pharmacokinetic limitations, research has concentrated on different TQ novel formulations and delivery systems. Here, we visualize the neuropharmacological potential, challenges, and delivery prospects of TQ, specifically focusing on neurological disorders along with its chemistry, pharmacokinetics, and toxicity.

Effects of Lippia sidoides essential oil, thymol, p-cymene, myrcene and caryophyllene on rat sciatic nerve excitability

Lippia sidoides Cham is a typical herb species of Northeast Brazil with widespread use in folk medicine. The major constituents of the essential oil of L. sidoides (EOLs) are thymol, p-cymene, myrcene, and caryophyllene. Several studies have shown that the EOLs and its constituents have pharmacological effects, including antibacterial, anti-inflammatory, antioxidant and neuroprotective activity. Therefore, this work aimed to investigate the effects of the EOLs and their main constituents on rat sciatic nerve excitability. The sciatic nerves of adult Wistar rats were dissected and mounted in a moist chamber. Nerves were stimulated by square wave pulses, with an amplitude of 40 V, duration of 100 μs to 0.2 Hz. Both EOLs and thymol inhibited compound action potential (CAP) in a concentration-dependent manner. Half maximal inhibitory concentration for CAP peak-to-peak amplitude blockade were 67.85 and 40 µg/mL for EOLs and thymol, respectively. CAP peak-to-peak amplitude was significantly reduced by concentrations ≥60 µg/mL for EOLs and ≥30 µg/mL for thymol. EOLs and thymol in the concentration of 60 µg/mL significantly increased chronaxie and rheobase. The conduction velocities of 1st and 2nd CAP components were also concentration-dependently reduced by EOLs and thymol in the range of 30-100 µg/mL. Differently from EOLs and thymol, p-cymene, myrcene and caryophyllene did not reduce CAP in the higher concentrations of 10 mM. These data demonstrated that EOLs and thymol inhibited neuronal excitability and were promising agents for the development of new drugs for therapeutic use.

Investigation of thymol effect on learning and memory impairment induced by intrahippocampal injection of amyloid beta peptide in high fat diet- fed rats

Obesity and consumption of a high fat diet (HFD) are known to increase the risk of Alzheimer's disease (AD). In the present study, we have examined the protective and therapeutic effects of thymol (main monoterpene phenol found in thyme essential oil) on a HFD-fed rat model of AD. Fourty adult male Wistar rats were randomly assigned to 5 groups:(n = 8 rats/group): group 1, control, consumed an ordinary diet, group 2 consumed a HFD for 8 weeks, then received phosphate-buffered saline (PBS) via intrahippocampal (IHP) injection, group 3 consumed HFD for 8 weeks, then received beta-amyloid (Aβ)1-42 via IHP injections to induce AD, group 4 consumed HFD for 8 weeks, then received Aβ1-42, and was treated by thymol (30 mg/kg in sunflower oil) daily for 4 weeks, and group 5 consumed HFD for 8 week, then received Aβ1-42 after what sunflower oil was administered by oral gavage daily for 4 weeks. Biochemical tests showed an impaired lipid profile and higher glucose levels upon consumption of HFD, which was ameliorated by thymol treatment. In behavioral results, spatial memory in group 3 was significantly impaired, but groups treated with thymol showed better spatial memory compared to group 3 (p ≤ 0.01). In histological results, formation of Aβ plaque in hippocampus of group 3 increased significantly compared to group 1 and group 2 (p ≤ 0.05), but group 4 showed decreased Aβ plaques compared to group 3 (p ≤ 0.01). In conclusion, thymol decreased the effects of Aβ on memory and could be considered as neuroprotective.

The role of metals in mammalian olfaction of low molecular weight organosulfur compounds

Covering: up to the end of 2017While suggestions concerning the possible role of metals in olfaction and taste date back 50 years, only recently has it been possible to confirm these proposals with experiments involving individual olfactory receptors (ORs). A detailed discussion of recent experimental results demonstrating the key role of metals in enhancing the response of human and other vertebrate ORs to specific odorants is presented against the backdrop of our knowledge of how the sense of smell functions both at the molecular and whole animal levels. This review emphasizes the role of metals in the detection of low molecular weight thiols, sulfides, and other organosulfur compounds, including those found in strong-smelling animal excretions and plant volatiles, and those used in gas odorization. Alternative theories of olfaction are described, with evidence favoring the modified "shape" theory. The use of quantum mechanical/molecular modeling (QM/MM), site-directed mutagenesis and saturation-transfer-difference (STD) NMR is discussed, providing support for biological studies of mouse and human receptors, MOR244-3 and OR OR2T11, respectively. Copper is bound at the active site of MOR244-3 by cysteine and histidine, while cysteine, histidine and methionine are involved with OR2T11. The binding pockets of these two receptors are found in different locations in the three-dimensional seven transmembrane models. Another recently deorphaned human olfactory receptor, OR2M3, highly selective for a thiol from onions, and a broadly-tuned thiol receptor, OR1A1, are also discussed. Other topics covered include the effects of nanoparticles and heavy metal toxicants on vertebrate and fish ORs, intranasal zinc products and the loss of smell (anosmia).

Different effects of (+)‑borneol and (‑)‑borneol on the pharmacokinetics of osthole in rats following oral administration

Osthole is the primary active component of a number of herbal plants such as the Cnidium monnieri fruit. In traditional Chinese herb medicine, osthole is commonly used in combination with borneol to obtain improved pharmacological effects. The aim of the present study was to investigate the effect of borneol enantiomers on the pharmacokinetics of osthole. An appropriate high‑performance liquid chromatography (HPLC) method was applied to determine the concentrations of osthole in plasma. Following oral administration of osthole alone or combined with borneol in rats, blood samples were collected and analyzed by HPLC. The results demonstrated that there were statistically significant differences in the pharmacokinetic parameters of osthole between osthole administration alone and co‑administration with borneol. When combined with synthetic borneol, the AUC0‑t, AUC0‑∞ and Cmax of osthole increased by 48.153, 104.708 and 92.630%, respectively, while the CL/F decreased by 51.251%. When combined with (+)‑borneol, the AUC0‑t, AUC0‑∞ and Cmax of osthole were increased by 61.561, 78.167, and 51.769%, respectively, while the CL/F decreased by 44.174% (P<0.01). In addition, when combined with (‑)‑borneol, the AUC0‑t, AUC0‑∞ and Cmax of osthole increased by 115.856, 167.786 and 271.289%, respectively, while the CL/F decreased by 60.686% (P<0.01). These results indicated that borneol may enhance gastrointestinal absorption and inhibit the metabolism of osthole. In addition, the promotional effect of (‑)‑borneol on the pharmacokinetic parameters of osthole was greater than that of (+)‑borneol.

Marine Cyclic Guanidine Alkaloids Monanchomycalin B and Urupocidin A Act as Inhibitors of TRPV1, TRPV2 and TRPV3, but not TRPA1 Receptors

Marine sponges contain a variety of low-molecular-weight compounds including guanidine alkaloids possessing different biological activities. Monanchomycalin B and urupocidin A were isolated from the marine sponge Monanchora pulchra. We found that they act as inhibitors of the TRPV1, TRPV2, and TRPV3 channels, but are inactive against the TRPA1 receptor. Monanchomycalin B is the most active among all published marine alkaloids (EC₅₀ 6.02, 2.84, and 3.25 μM for TRPV1, TRPV2, and TRPV3, correspondingly). Moreover, monanchomycalin B and urupocidin A are the first samples of marine alkaloids affecting the TRPV2 receptor. Two semi-synthetic urupocidin A derivatives were also obtained and tested against TRP (Transient Receptor Potential) receptors that allowed us to collect some data concerning the structure-activity relationship in this series of compounds. We showed that the removal of one of three side chains or double bonds in the other side chains in urupocidin A led to a decrease of the inhibitory activities. New ligands specific to the TRPV subfamily may be useful for the design of medicines as in the study of TRP channels biology.

Blocking TRPA1 in Respiratory Disorders: Does It Hold a Promise?

Transient Receptor Potential Ankyrin 1 (TRPA1) ion channel is expressed abundantly on the C fibers that innervate almost entire respiratory tract starting from oral cavity and oropharynx, conducting airways in the trachea, bronchi, terminal bronchioles, respiratory bronchioles and upto alveolar ducts and alveoli. Functional presence of TRPA1 on non-neuronal cells got recognized recently. TRPA1 plays a well-recognized role of “chemosensor”, detecting presence of exogenous irritants and endogenous pro-inflammatory mediators that are implicated in airway inflammation and sensory symptoms like chronic cough, asthma, chronic obstructive pulmonary disease (COPD), allergic rhinitis and cystic fibrosis. TRPA1 can remain activated chronically due to elevated levels and continued presence of such endogenous ligands and pro-inflammatory mediators. Several selective TRPA1 antagonists have been tested in animal models of respiratory disease and their performance is very promising. Although there is no TRPA1 antagonist in advanced clinical trials or approved on market yet to treat respiratory diseases, however, limited but promising evidences available so far indicate likelihood that targeting TRPA1 may present a new therapy in treatment of respiratory diseases in near future. This review will focus on in vitro, animal and human evidences that strengthen the proposed role of TRPA1 in modulation of specific airway sensory responses and also on preclinical and clinical progress of selected TRPA1 antagonists.

Feeling Nature's PAINS: Natural Products, Natural Product Drugs, and Pan Assay Interference Compounds (PAINS)

We have previously reported on classes of compounds that can interfere with bioassays via a number of different mechanisms and termed such compounds Pan Assay INterference compoundS, or PAINS. These compounds were defined on the basis of high-throughput data derived from vendor-supplied synthetics. The question therefore arises whether the concept of PAINS is relevant to compounds of natural origin. Here, it is shown that this is indeed the case, but that the context of the biological readout is an important factor that must be brought into consideration.