An interesting news item caught my attention this week, about how menthol may have potential for treating Alzheimer’s diseases. The research article is cited below.
Menthol is a small monoterpenoid molecule with bits that can be twisted round into 8 different configurations that chemists call stereoisomers. The form that predominates in nature has a fresh, minty flavour and odour. Other forms have an unpleasant earthy smell. This poses a challenge for industrial synthesis (Dylong et al, 2022). Nature is much moreselective, synthesising the favoured “(1R,2S,5R)” menthone isomer without the others.
The best known natural source of menthol is wild mint (Mentha arvensis, Lamiaceae) that grows wild right across Eurasia and North America. This and other mint species have been used for millennia as leaves, decoctions (teas) and essential-oil extracts. Besides the minty flavour, menthol has a cooling effect on the skin and soothes sore throats. Itis widely used in analgesic skin products, toothpastes, mouthwashes, decongestants, throat sprays and lozenges, cough remedies, etc. It also assists the transdermal delivery of other pharmacologically-active molecules. In cleaning products menthol is used for its smell and its antimicrobial and insect-repellingproperties,
In recent research, Casares et al (2023) tested the known immune-modulating properties of menthol for treating neurodegenerative diseases, specifically Alzheimer’s. The animals in the study were exposed to menthol vapours, resulting in marked improvement of their cognitive abilities. Though not mentioned in the scientific article, commentaries in the popular presspoint out that menthol cigarettes (now banned in some countries) have been popular for decades, with the menthol easing throat irritation cause by the smoke.
Menthol is apparently good for our physical, and perhaps also our mental wellbeing. I will go and enjoy some mint tea, without too much sugar and without cigarette smoke.
Further reading
🧠 CasaresN et al (2023). Improvement of cognitive function in wild-type and Alzheimer´s disease mouse models by the immunomodulatory properties of menthol inhalationor by depletion of T regulatory cells. Frontiers in immunology, 14,1130044. https://doi.org/10.3389/fimmu.2023.1130044
🌿 Dylong D et al (2022). Synthesis of(−)‐menthol: industrial synthesis routes and recent development. Flavour and Fragrance Journal, 37(4), 195-209. https://doi.org/10.1002/ffj.3699
🌿 Wikipedia (2024, May 2). Menthol. https://en.wikipedia.org/w/index.php?title=Menthol&oldid=1221935797
🌿 National Center for Biotechnology Information(2024). PubChem Compound Summary for CID 1254, Menthol. https://pubchem.ncbi.nlm.nih.gov/compound/Menthol.
