Wintergreen Gaultheria procumbens
Wintergreen Gaultheria procumbens
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Wintergreen is an evergreen shrub of which there are a few varieties. From the genus Pyrola there are 12 species. Gaultheria procumbens, the species analysed here, grows well in northern United States and southern Canada. It is also called teaberry (from a beverage made from soaking the leaves), or checkerberry. The leaves are shiney and tooth edged, they remain quite shiney when dried and some what mottled.
My name is Laila, I am a grade 12 student who is off to university for biomedical and mechanical engineering this upcoming school year.
I have a passion for all things science, but particularly chemistry and physics.
During my time as a CO-OP student here, using gas-chromatography mass spectrometry combined my love for physics with my love for chemistry.
I used GC-MS to observe the various compounds I extracted from the wintergreen plant. As you may have probably guessed by now, I specifically focused on Methyl salicylate, a compound I find very interesting given both its medicinal and flavor properties.
I hope to continue doing projects similar to this in the future.
50g of dried wintergreen leaves, were purchased from a local health food store (this was all there was for sale). These were soaked over night in 50ml of distilled water, to help rehydrate the leaves. The rehydrated leaves were then microwave distilled for 7 mins, the distillate was collected in a beaker in the middle of the microwave vessel. An ice puck contained in the lid of the vessel, condensed the vapourised volatile organic compounds into the beaker. The beaker containing the "hydrosol", water soluble components was allowed to cool and then further procedures were carried out on the hydrosol to discover what chemicals it contained.
The hydrosol had a strong minty smell similar to chewing gum.
To analyse the chemicals contained in the winter green hydrosol, the water needed to be removed using solid phase micro extraction cartridges. These held the organic molecules and a methanol/acetonitrile wash then concentrated them and eluted them into the organic solvent suitable for the next step.
Methyl salicylate, commonly found within wintergreen Gaultheria procumbens, is a popular chemical that has long been prized for its distinctive “minty” flavour, prompting companies to adopt its use into gum, mints and mouthwash for instance. Methyl salicylate was derived from the American wintergreen in 1843 by the chemist Auguste André Thomas Cahours, but before that it was frequently used by Indigenous nations as a medical remedy. Methyl salicylate can be used as a topical analgesic (i.e. applied on the skin for pain relief) in higher concentrations, although there is little proof for this. In lower concentrations, as I have already mentioned, Methyl salicylate is a preferred flavor additive for “minty” products.
Methyl 2-hydroxybenzoate is the IUPAC (International Union of Pure and Applied Chemistry) name for Methyl salicylate. Despite this seemingly more complex name, it refers to simply a chain of 6 carbons in a hexagonal shape, with a carbon connected to another carbon outside of this hexagon, with two oxygens bound to it. On one of the oxygens lies yet another carbon, the whole molecule written simply as C8H8O3 : eight carbon atoms, eight hydrogen atoms and three oxygen atoms make such a remarkable compound. Aside from its derivation from wintergreen plants, it can be synthesized through the methanol esterification of salicylic acid. In layman's terms, adding methanol (four hydrogens, one carbon and one oxygen) to salicylic acid, virtually the same as the Methyl salicylate created after this combination.
There are only 3 compounds in the wintergreen hydrosol.
Methyl salicylate, carvone and eugenol. Carvone exists as two chiral molecules. The GC can not separate them not even the chiral GC, but our noses can tell the difference! R carvone is predominately in carraway, while S carvone is in spearmint. Two very different smells. Wintergreen has a minty smell so i am guessing it contains S carvone and not R.
Eugenol is the compound associated with clove.
To quantify the amounts of each chemical species contained in each hydrosol, a calibrant is added at different concentrations. This compound is very similar to the terpenoids but is a species not occuring naturally in any plants we have studied. The calibrant is spiked into each hydrosol before the SPE is used. The calibrant is at varying known concentrations, similar to what we have found the chemical concentrations to be in the hydrosols. The wintergreen is processed 6 times with 6 different concentrations of calibrant. This way we check the reproducibility of the concentrations and calculate the actual concentrations from a linear graph of the known calibrant concentrations.
| Chemical | Amount |
| methyl salicylate | 43mg/L |
| carvone | 4.9mg/L |
| eugenol | 4.6mg/L |
