Modulation of transient receptor potential (TRP) channels by plant derived substances used in over-the-counter cough and cold remedies

Abstract

Background Upper respiratory tract infections (URTIs) impact all age groups and have a significant economic and social burden on society, worldwide. Most URTIs are mild and self-limiting, but due to the wide range of possible causative agents, including Rhinovirus (hRV), Adenovirus, Respiratory Syncytial Virus (RSV), Coronavirus and Influenza, there is no single and effective treatment. Over-the-counter (OTC) remedies, including traditional medicines and those containing plant derived substances, help to alleviate symptoms including inflammation, pain, fever and cough. Purpose This systematic review focuses on the role of the major plant derived substances in several OTC remedies used to treat cold symptoms, with a particular focus on the transient receptor potential (TRP) channels involved in pain and cough. Methods Literature searches were done using Pubmed and Web of Science, with no date limitations, using the principles of the PRISMA statement. The search terms used were ‘TRP channel AND plant compound’, ‘cough AND plant compound’, ‘cough AND TRP channels AND plant compound’, ‘cough AND P2X3 AND plant compound’ and ‘P2X3 AND plant compound’ where plant compound represents menthol or camphor or eucalyptus or turpentine or thymol. Results The literature reviewed showed that menthol activates TRPM8 and may inhibit respiratory reflexes reducing irritation and cough. Menthol has a bimodal action on TRPA1, but inhibition may have an analgesic effect. Eucalyptus also activates TRPM8 and inhibits TRPA1 whilst down regulating P2X3, aiding in the reduction of cough, pain and airway irritation. Camphor inhibits TRPA1 and the activation of TRPM8 may add to the effects of menthol. Activation of TRPV1 by camphor, may also have an analgesic effect. Conclusions The literature suggests that these plant derived substances have multifaceted actions and can interact with the TRP ‘cough’ receptors. The plant derived substances used in cough and cold medicines have the potential to target multiple symptoms experienced during a cold.

Lung transcriptomics reveals the underlying mechanism by which aerobic training enhances pulmonary function in chronic obstructive pulmonary disease

“…Additionally, published data indicated that the activation of TRPM8 channels might result in the production of inflammatory mediators [ 48 ]. There is still some controversy over the current data, as some studies have suggested that the activation of TRPM8 channels inhibits the cough response [ 49 , 50 ]. However, the results of this study indicated that TRPM8, as a differentially expressed gene, was downregulated after exposure to cigarette smoke but activated after exercise training, which suggested a positive role for TRPM8 in improving pulmonary function in mice with COPD through exercise.…”

Ingredients of Vicks VapoRub inhibit rhinovirus-induced ATP release

“…Some of these plant extracts are likely to include a mixture of compounds with varying degrees of medicinal properties. 29 For example, eucalyptus oil consists of multiple different chemical compounds at different concentrations, which may have varying interactions with the TRP channels studied. Furthermore, the three and four VVRI mixtures utilized do not represent the exact concentration of each ingredient used in Vicks VapoRub.…”

Supramolecular Structure of the β-Cyclodextrin Metal–Organic Framework Optimizes Iodine Stability and Its Co-delivery with l-Menthol for Antibacterial Applications

“…The URT infections are often accompanied by symptoms such as cough, sore throat, and breathing difficulties, which are difficult to treat with single antipathogen therapy. 14,15 L-menthol serves as a cooling mimic and activator of the cold-sensitive transient receptor potential melastatin-8 (TRPM8) channels. 16,17 It stimulates the TRPM8 channels of the trigeminal nerve in the airways, inducing a cooling sensation, and thereby alleviating symptoms of throat pain, inflammation, and dyspnea.…”

“…Consequently, it is evident that the bactericidal and antiviral capabilities of I 2 are highly valuable for application against URT infections. The URT infections are often accompanied by symptoms such as cough, sore throat, and breathing difficulties, which are difficult to treat with single antipathogen therapy. , l -menthol serves as a cooling mimic and activator of the cold-sensitive transient receptor potential melastatin-8 (TRPM8) channels. , It stimulates the TRPM8 channels of the trigeminal nerve in the airways, inducing a cooling sensation, and thereby alleviating symptoms of throat pain, inflammation, and dyspnea. − Therefore, the anti-inflammatory properties of l -menthol combined with the bactericidal and antiviral effects of I 2 can be utilized to the maximum extent in alleviating and treating URT infection symptoms through codelivery after being loaded into suitable carriers.…”