Analysis of Essential Oils and Chemotype Verification: Safety and Therapeutic Aspects
The chemotype of an essential oil refers to its specific chemical composition, which can vary within the same botanical species depending on geographic origin, cultivation conditions, or extraction method. This chemical profile determines its therapeutic properties, efficacy, and safety of use. Ignoring chemotype can lead to usage errors, sometimes severe. This article explores the implications of this concept, its relevance in phytovigilance, and the reference analytical methods (GC, MS) required to ensure quality and prevent risks. An essential topic for safe and controlled aromatherapy.
Esméralda Cicchetti
5/10/20254 min read
What is a chemotype?
A chemotype describes the chemical variation within a single plant species, influenced by environmental conditions, cultivation region, and extraction methods. In other words, it is the specific chemical profile of an essential oil, which can vary significantly even among specimens of the same botanical species.
Understanding the concept of chemotype is essential when working with aromatherapy and essential oil use. Indeed, the therapeutic properties of an essential oil can be strongly influenced by its chemical composition. Knowing the chemotype allows selection of the oil best suited to a specific need, ensuring both safe and effective use.
Examples of chemotypes: thyme essential oil
To illustrate the importance of chemotype identification, thyme is a particularly relevant example.
We refer to “thyme to ‘xxx’”, where xxx corresponds to the main molecule or chemical marker of the essential oil.
Thus, several thyme chemotypes can be distinguished, including:
thymol: anti-infectious, analgesic
borneol: tonic, analgesic
linalool: mild antibacterial, tonic
geraniol: antibacterial, antifungal, antiviral
thujanol: antibacterial, antifungal, antiviral, warming, liver-regenerating
eucalyptol (1,8-cineole): expectorant, antibacterial, antifungal, antiviral
Beyond therapeutic differences, chemotype also has a major impact on the safety of essential oil use.
Phytovigilance and chemotype
The safety of essential oils is a major concern for users, whether in aromatherapy or cosmetology. Each essential oil has a unique chemotype that determines not only its therapeutic properties but also its safety profile. These properties must be assessed prior to use in order to avoid potential adverse effects.
Phytovigilance refers to the monitoring of adverse effects and interactions related to the use of medicinal plants, whether used as medicines, food supplements, cosmetics, or other forms. It encompasses pharmacovigilance, nutrivigilance, cosmetovigilance, addictovigilance, and toxicovigilance, and constitutes a legal requirement in Europe.
Risks associated with improper use of essential oils are real and may include skin irritation, allergic reactions, and even neurotoxicity in the case of certain compounds. Health authorities (ANSM/Regional Pharmacovigilance Centers (CRPV)/European Medicines Agency (EMA), ANSES, European Commission via the Cosmetic Products Notification Portal (CPNP)) play a key role in the health assessment, monitoring, and regulation of these products. They establish guidelines and safety standards to ensure that essential oils available on the market are safe for consumers.
Depending on the type of use, the vigilance system and responsible authority differ:
Pharmacovigilance: herbal medicines, phyto-aromatherapy
Phytovigilance: herbal medicinal products
Nutrivigilance: food supplements based on extracts, including essential oils
Cosmetovigilance: cosmetic products containing plant extracts, including essential oils
Addictovigilance: plants or extracts with psychoactive or dependence-inducing properties
Toxicovigilance: accidental or abusive exposure to plants and extracts, including toxic essential oils
The case of rosemary is particularly illustrative of phytovigilance issues linked to lack of chemotype awareness.
Thus, rosemary (Rosmarinus officinalis) camphor chemotype is epileptogenic and hepatotoxic, whereas the verbenone chemotype is considered hepatoprotective.
Analytical methods for essential oil chemotype determination
Chemotype analysis of essential oils is a fundamental process to ensure quality and therapeutic efficacy. Its verification is also crucial in the regulation of perfumes, aromatic products, and pharmaceutical products. Quality and safety standards (AFNOR, pharmacopoeias, etc.) require users to be informed of possible differences between chemotypes.
Among analytical methods used to define chemotypes, gas chromatography (GC) and mass spectrometry (MS) stand out due to their precision and ability to identify various chemical components. Gas chromatography separates volatile mixture constituents, providing a clear view of an essential oil’s composition.
Mass spectrometry provides complementary information essential for identification. By correlating GC and MS data, a comprehensive chemical profile of essential oils can be established, enabling chemotype verification. This is essential to ensure product authenticity and to prevent the presence of contaminants or unwanted compounds that could affect therapeutic use. Analyses based solely on flame ionization detection (FID) are insufficient to ensure compound identification in complex mixtures.
Conclusion and recommendations
In summary, essential oil analysis and chemotype verification are critical elements for ensuring safety and therapeutic efficacy. Although natural, essential oils may present risks if not properly analyzed. Differentiating chemotypes allows not only the identification of specific properties but also the reduction of adverse effects associated with misuse or poor-quality products. This highlights the importance of a rigorous approach in selecting and using essential oils.
For practitioners, it is recommended to integrate scientific analytical methods to confirm the identity and quality of essential oils before use. This includes systematically verifying chemotype analysis results and relying on trusted, recognized sources for product sourcing. Continuous training on recent developments in aromatherapy and toxicology is also advised to maintain optimal safety standards.
Users, in turn, should be encouraged to consult a healthcare professional before using essential oils, particularly those with strong activity or contraindications. Skin patch testing is recommended to detect allergies, and recommended dosages must be strictly respected. Clear labeling and documentation of used essential oils also contribute to safer use.
Ultimately, an informed and cautious approach to essential oil use, supported by proper chemotype verification, is key to maximizing benefits while minimizing associated risks.
For analytical support related to essential oils, contact us.
References
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Franchomme P., Jollois R., Pénoël D. Aromatherapy Precisely. Roger Jollois Editions, 2001.
Essential oils: use with caution! ANSES, 2024, Vigil’Anses Bulletin, p. 6.
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ANSM. Good Pharmacovigilance Practices. 2022.
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Cosmetovigilance and tattoo vigilance. ANSES, 2023.
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