Thymol

(also known as 2-isopropyl-5-methylphenol, IPMP) is a natural monoterpene phenol derivative of cymene, C10H14O, isomeric with carvacrol, found in oil of thyme, and extracted from Thymus vulgaris (common thyme) and various other kinds of plants as a white crystalline substance of a pleasant aromatic odor and strong antiseptic properties. Thymol also provides the distinctive, strong flavor of the culinary herb thyme, also produced from T. vulgaris.

Careful with the word ‘phenolic’ that is often encountered as an off-note. The simplest phenol of importance is thymol, which is used for both its odor and antiseptic properties in personal care products. Slightly soluble in water at neutral pH, but it is extremely soluble in alcohols and other organic solvents. It is also soluble in strongly alkaline aqueous solutions due to deprotonation of the phenol.

Discovery of Thymol:

The bee balms Monarda fistulosa and Monarda didyma, North American wildflowers, are natural sources of thymol. The Blackfoot Native Americans recognized these plants’ strong antiseptic action and used poultices of the plants for skin infections and minor wounds. A tisane made from them was also used to treat mouth and throat infections caused by dental caries and gingivitis.
Thymol was first isolated by the German chemist Caspar Neumann in 1719. In 1853, the French chemist A. Lallemand named thymol and determined its empirical formula. First synthesized by the Swedish chemist Oskar Widman in 1882.
Preliminary research demonstrates that it can reduce bacterial resistance to antibiotics, and maybe a fungicide. the thyme isolate demonstrates post antibacterial effect against some microorganisms. This antibacterial activity is caused by inhibiting growth and lactate production, and by decreasing cellular glucose uptake.
The anti-fungal nature of the isolate is due to its ability to alter the hyphal morphology and cause hyphal aggregates, resulting in reduced hyphal diameters and lyses of the hyphal wall. Additionally, thymol is lipophilic, enabling it to interact with the cell membrane of fungus cells, altering cell membrane permeability permitting the loss of macromolecules.

Profile:

• 📂 CAS N° — 89-83-8

• ⚖️ MW — 150.22 g/mol

• 📝 Odor Type — Fresh

• 📈 Odor Strength — high. recommend smelling in 10% sol. Stays 176 Hours on strip.

• 👃🏼 Odor Profile — Spicy, phenolic, and thymol with a chemical, medicinal, camphoraceous nuance. warm, thyme-like. Smells like dirty rosemary, very agrestic.Powerful, sweet-medicinal, herbaceous and warm odor of moderate tenacity. The odor is much more pleasant than that of Phenol (or Cresol) and not nearly as “dry-tarry” as that of Carvacrol (an isomer of Thymol).

• 👅 Flavor Profile — Phenolic, medicinal, woody and spicy. The taste is pleasantly sweet-medicinal, herbaceous-spicy at concentrations up to 20 ppm (alone) or much higher in compositions (100 ppm in the presence of Menthol-EucaIyptol ,etc. is still not unpleasantly medicinal).

• ⚗️ Use — mint, savory spices, fruity citrus compositions. It is used in discrete amounts in perfumes, although Thyme oil, for its mellower, softer effect and its reasonable cost. Inexpensive synthetic Thymol has appeared on the world market since 1960 when the price fell considerably below that of Menthol.

• It is more commonly used in flavor compositions, mainly in toothpaste flavor, cough drops, mouthwashes, gargles and chewing gums. It is often used partly for its antiseptic effect in such products. The concentration may vary from 2 to I00 ppm, highest in chewing gums.

A newer use of Thymol is that in imitation Mandarin flavor, since the material was identified in Mandarin peel oil in 1963. It blends excellently with Citrus, Mint, Spice and herbaceous flavor materials or with fruity complexes.

Natural Occurrence:

Thymol can be found in:

• Euphrasia rostkoviana

• Monarda didyma

• Monarda fistulosa

• Trachyspermum ammi

• Origanum compactum

• Origanum dictamnus

• Origanum onites

• Origanum vulgare

• Thymus glandulosus

• Thymus hyemalis

• Thymus vulgaris

• Thymus zygis

Other Uses:

Thymol has been used in alcohol solutions and in dusting powders for the treatment of tinea or ringworm infections and was used in the United States to treat hookworm infections.
People of the Middle East continue to use za’atar, a delicacy made with large amounts of thyme, to reduce and eliminate internal parasites. It is also used as a preservative in halothane, an anesthetic, and as an antiseptic in mouthwash. When used to reduce plaque and gingivitis, thymol has been found to be more effective when used in combination with chlorhexidine than when used purely by itself. Thymol is also the active antiseptic ingredient in some toothpaste, such as Johnson & Johnson’s Euthymol. Thymol has been used to successfully control varroa mites and prevent fermentation and the growth of mold in bee colonies, methods developed by beekeeper R. O. B. Manley.
Thymol is also used as a rapidly degrading, non-persisting pesticide.
Thymol can also be used as a medical disinfectant and general purpose disinfectant.

References:

FEMA Gras No.3066

Interesting reading on thymol and the inflammatory response

Antibacterial and antifungal activities of thymol: A brief review of the literature

Production of Thymol:

• from para-Cymene or from Nitrocuminaldehyde.

• from para-Cresol via its Sulfonate to the iso-Propyl-derivative.

• from Piperitone by dehydrogenation. The process yields Menthol plus Thymol. The two materials can be satisfactorily separated.

• The process of isolation from Ajowan oil is only of local importance.

Notes:

Thymol is strongly antiseptic, but relatively non-toxic. It is estimated that Thymol is about 5 times less toxic than Phenol by human ingestion.

• Fulvio Ciccolo.

• Wikipedia

• Perfume and Flavor Chemicals - Steffen Arctander.

• National Center for Biotechnology Information (2020). PubChem Compound Summary for CID 6989, Thymol. Retrieved November 24, 2020 from https://pubchem.ncbi.nlm.nih.gov/compound/Thymol.