Eugenyl acetate: properties, uses, pros, cons, safety

Eugenyl Acetate is an aromatic substance belonging to the class of phenolic esters. It is the acetylated derivative of eugenol and is mainly used in fragrances, perfumery and, when supplied in a suitable grade, as a flavouring substance. It has a characteristic sweet, spicy and floral odour, with a note reminiscent of clove. Its documented cosmetic function is related to perfuming the product and/or the skin.

Description

Eugenyl Acetate is a chemically defined substance, not a botanical extract or a complex natural mixture. Chemically, it derives from eugenol through conversion of the phenolic hydroxyl group into the corresponding acetic ester.

This structural modification gives it properties that differ from free eugenol, while retaining a marked olfactory affinity with spicy and clove-like notes. The FAO/JECFA specification describes Eugenyl Acetate as a solid that may melt at relatively warm room temperature to form a pale yellow liquid, with a mild clove-like odour.

Eugenyl Acetate also occurs naturally. It is one of the characteristic components of the essential oil of Syzygium aromaticum, clove, together mainly with eugenol, β-caryophyllene and α-humulene. Its percentage may vary considerably depending on the raw material, the plant part and the extraction method: analytical studies on clove oils report substantial variation among samples.

However, its natural occurrence does not mean that commercial Eugenyl Acetate is necessarily obtained directly from an essential oil. It may be isolated from natural sources or produced by chemical transformation of eugenol.

Production process

One of the main preparation routes is the acetylation of eugenol. The hydroxyl group of eugenol is reacted with an acetylating agent to produce Eugenyl Acetate.

Several production processes have been investigated, including catalysed chemical systems and enzymatic methods. Synthesis may also start from clove essential oil rich in eugenol, converting the latter into the corresponding acetate.

Once the reaction is complete, the product must be separated from residual reagents and unconverted substances and subsequently purified. The commercial grade is then checked using analytical techniques such as gas chromatography.

The JECFA specification for flavour use requires a minimum assay of 98%, while commercial analytical grades may similarly be specified at more than 98% purity by GC.

Actual quality nevertheless depends on the grade purchased. For cosmetic, food or analytical applications, the relevant supplier specifications and documentation must be used.

Main substances contained

In the case of Eugenyl Acetate, the expression “main substances contained” must be interpreted differently from a plant extract or essential oil, because this is an essentially single-component chemical substance.

The main components that may be considered are:

• Eugenyl Acetate: the principal substance. In grades complying with the JECFA specification, it represents at least 98% of the material.
• Eugenol: it may be present in trace amounts as unreacted starting material when Eugenyl Acetate is produced by acetylation of eugenol. Its presence and concentration are not universally defined and must be checked in the certificate of analysis for the specific batch.
• Residual process substances: these may occur at very low levels depending on the production technology and purification process. They are not mandatory characteristic constituents of the ingredient and must be verified in the manufacturer's documentation.
• Water, residual solvents and other analytical impurities may account for part of the fraction not assigned to Eugenyl Acetate in different commercial grades, but there is no single standard composition valid for every supplier.

It is therefore incorrect to list eugenol, β-caryophyllene, α-humulene or other constituents of clove essential oil as substances necessarily contained in purified Eugenyl Acetate. These are components of the natural starting material, whereas high-purity commercial Eugenyl Acetate consists essentially of the single substance itself.

Identification data and specifications

The principal identification data are reported in FAO/JECFA specifications and European regulatory sources.

Indicative physicochemical properties

JECFA data also indicate a melting point of approximately 25 °C; commercial specifications may report values around 26 °C and describe the product as solid or as a clear liquid depending on temperature.

Food

Eugenyl Acetate is recognised as a flavouring substance. It is not a nutrient, and its food use is intended solely to modify or contribute to the aroma of a product.

JECFA identifies it as substance No. 1531 and classifies it as a flavouring agent. In its 2005 evaluation, the Committee concluded that there was no safety concern at current estimated levels of intake when used as a flavouring substance.

Within the European Union, it is identified as FL 09.020 in the list of flavouring substances.

Food use nevertheless requires a grade specifically suitable for food applications. A raw material purchased for perfumery, laboratory or cosmetic use must not automatically be considered suitable for food.

Cosmetics

In cosmetics, Eugenyl Acetate is used as a fragrance component. Its function is to improve the odour of the cosmetic product and/or perfume the skin.

It may be used in fragrance compositions for:

• perfumes and eau de parfum;
• eau de toilette;
• creams and lotions;
• cleansers;
• shampoos and hair products;
• deodorants;
• body products;
• soaps and other perfumed cosmetic products.

Its olfactory profile is particularly suitable for floral, spicy, carnation-like, balsamic and oriental compositions.

From a regulatory standpoint, Eugenyl Acetate became particularly relevant following Regulation (EU) 2023/1545. It is included in entry 368 of Annex III to the EU Cosmetics Regulation and must be individually declared in the ingredient list when its concentration exceeds:

• 0.001% in leave-on products;
• 0.01% in rinse-off products.

These are ingredient-list declaration thresholds, not general maximum permitted concentrations.

The new requirements apply to cosmetic products placed on the EU market from 31 July 2026. A transitional period allows products placed on the market under the previous requirements to continue being made available until 31 July 2028.

Pros

• It has a characteristic and recognisable floral-spicy, clove-like odour.
• It is effective as a perfumery component.
• It is soluble in ethanol and oily phases.
• It is available as a high-purity chemical substance.
• It may have natural, semi-synthetic or synthetic origin.
• It occurs naturally in aromatic essential oils, particularly clove oil.
• It is identified and standardised in the flavour sector through JECFA, FEMA and FLAVIS.
• Its composition is easier to control than that of a complex essential oil.

Cons

• It is a fragrance allergen subject to specific declaration in cosmetics sold in the European Union above the applicable thresholds.
• It is practically insoluble in water.
• It may require alcohol, solubilisers or an oily phase for incorporation into formulations.
• Its melting point close to room temperature may cause solidification or crystallisation during storage.
• It is not a skin-conditioning ingredient or dermatological active: its principal cosmetic role is olfactory.
• Natural occurrence in essential oils does not remove the obligation to assess and declare it where required.
• When present as a constituent of natural aromatic raw materials, its contribution must be included when calculating the total concentration in the finished product.
• Different commercial grades must not automatically be considered interchangeable for cosmetic, food or analytical use.

Safety, regulations and environment

The main cosmetic safety consideration concerns the potential for fragrance sensitisation.

The European Commission's Scientific Committee on Consumer Safety has examined the behaviour of esters of important contact allergens. Eugenyl Acetate has been included among esters that may undergo enzymatic hydrolysis in the skin, producing the corresponding parent compound. Exposure, metabolic conversion and possible cross-reactivity therefore need to be considered in the safety assessment.

This does not mean that every user will develop an allergy. Individual declaration of fragrance allergens is primarily intended to allow people who are already sensitised to identify the relevant substances more easily in cosmetic products.

For the finished cosmetic product, it is therefore important to know not only the amount of Eugenyl Acetate added directly, but also the quantity potentially introduced through:

• fragrances;
• essential oils;
• aromatic extracts;
• fragrance mixtures;
• other natural raw materials.

For a professional assessment of the raw material, it is advisable to obtain:

• updated SDS;
• certificate of analysis;
• assay and purity;
• analytical method;
• origin of the substance;
• possible residual Eugenol content;
• impurity profile;
• possible residual solvents;
• allergen declaration;
• relevant IFRA documentation where applicable to the fragrance composition;
• cosmetic compliance statement;
• storage conditions;
• stability data;
• specific instructions for handling the concentrated raw material.

In a high-purity grade, the percentage not attributed to Eugenyl Acetate must not automatically be interpreted as Eugenol. Only the batch COA and chromatographic analysis can establish which substances are actually present.

From an environmental standpoint, a potentially natural origin should not be interpreted as an automatic guarantee of environmental harmlessness. The concentrated raw material should be handled and disposed of according to its SDS, avoiding uncontrolled release into water and the environment.

Conclusion

Eugenyl Acetate is a chemically defined aromatic substance derived from eugenol and used mainly as a fragrance ingredient. It also occurs naturally in some essential oils, particularly clove oil, but the high-purity commercial product should not be confused with the essential oil from which it may originate.

The section “Main substances contained” therefore has a precise meaning: in a purified grade, the predominant substance is Eugenyl Acetate itself, normally at least 98% in products complying with the JECFA specification; Eugenol and other substances may only occur as residual components or variable impurities and must be verified in the certificate of analysis.

In cosmetics, its value is mainly olfactory. Its spicy and floral profile makes it useful in perfumery, but the substance is now included among the fragrance allergens subject to individual declaration in the European Union. Its presence must be declared when it exceeds 0.001% in leave-on products or 0.01% in rinse-off products.

A proper assessment should therefore consider purity, the actual concentration in the finished product, contributions from other aromatic raw materials, allergens, stability, SDS, COA and regulatory compliance. Under these conditions, Eugenyl Acetate can be used as a well-characterised aromatic component, while maintaining particular attention to labelling and fragrance sensitisation.

References________________________________________________________________________

Acosta-Smith E, Leon-Sicairos N, Tiwari S, Flores-Villaseñor H, Canizalez-Roman A, Kumavath R, Ghosh P, Azevedo V, Barh D. Piper betel Compounds Piperidine, Eugenyl Acetate, and Chlorogenic Acid Are Broad-Spectrum Anti-Vibrio Compounds that Are Also Effective on MDR Strains of the Pathogen. Pathogens. 2019 May 13;8(2):64. doi: 10.3390/pathogens8020064. 

Abstract. The natural population of the aquatic environment supports a diverse aquatic biota and a robust seafood industry. However, this environment also provides an appropriate niche for the growth of pathogenic bacteria that cause problems for human health. For example, species of the genus Vibrio inhabit marine and estuarine environments. This genus includes species that are pathogenic to aquaculture, invertebrates, and humans. In humans, they can cause prominent diseases like gastroenteritis, wound infections, and septicemia. The increased number of multidrug resistant (MDR) Vibrio strains has drawn the attention of the scientific community to develop new broad-spectrum antibiotics. Hence, in this paper we report the bactericidal effects of compounds derived from Piper betel plants: piperidine, chlorogenic acid, and eugenyl acetate, against various strains of Vibrio species. The different MIC90 values were approximately in a range of 2-6 mg/mL, 5-16 mg/mL, 5-20 mg/mL, and 30-80 mg/mL, for piperidine, chlorogenic acid, and eugenyl acetate, respectively. Piperidine showed the best anti-Vibrio effect against the five Vibrio species tested. Interestingly, combinations of sub-inhibitory concentrations of piperidine, chlorogenic acid, and eugenyl acetate showed inhibitory effects in the Vibrio strains. Furthermore, these compounds showed synergism or partial synergism effects against MDR strains of the Vibrio species when they were incubated with antibiotics (ampicillin and chloramphenicol).

Rastogi, S. C., & Johansen, J. D. (2008). Significant exposures to isoeugenol derivatives in perfumes. Contact Dermatitis, 58(5), 278-281.

Abstract. Background: Isoeugenol, an important fragrance allergen in consumers, has been restricted to 200 p.p.m. since 1998 according to guidelines issued by the fragrance industry. However, no decline in contact allergy to isoeugnol has been detected. It has been speculated that isoeugenol derivatives, especially isoeugenyl acetate, are used instead. Isoeugenyl acetate is probably metabolized in the skin to isoeugenol and gives positive patch test reactions in 1/3 of isoeugenol-sensitized individuals. Objectives: To investigate the content of isoeugenol, isoeugenyl acetate, and two isoeugenol ethers in perfumes/aftershaves. Materials and methods: 29 international brand perfumes/aftershaves were analysed for the target fragrance ingredient by gas chromatography–mass spectrometery. All samples were analysed in duplicate at detection levels of 1–5 p.p.m. Results: 16 products (55%) contained isoeugenol. The maximum concentration was 202 p.p.m. 10 products (34%) contained isoeugenyl acetate, which in 9 cases occurred together with isoeugenol. The concentrations of isoeugenyl acetate ranged from 20 to 4689 p.p.m. 13 products (44%) contained 64.9–1755.0 p.p.m. isoeugenyl methyl ether. Isoeugenyl benzyl ether was not detected in any of the investigated products. Conclusions: Isoeugenyl acetate is present in perfumes/aftershaves, in some products in significant amounts. This may lead to elicitation of contact allergy in isoeugenol-sensitized individuals and may contribute to unchanged levels of isoeugenol sensitization.

dos Santos, P., Zabot, G. L., Meireles, M. A. A., Mazutti, M. A., & Martinez, J. (2016). Synthesis of eugenyl acetate by enzymatic reactions in supercritical carbon dioxide. Biochemical Engineering Journal, 114, 1-9.

Abstract. Supercritical carbon dioxide (SC-CO2) as reaction medium has gained attention in the production of terpenic esters catalyzed by lipases. Therefore, this work investigated the production of eugenyl acetate by esterification of eugenol and acetic anhydride in SC-CO2 using two commercial lipases (Lipozyme 435 and Novozym 435) as catalysts. The influence of enzyme concentration (1⿿10% weight/weight), substrates⿿ molar ratio (1:1 to 5:1), temperature (40⿿60 °C) and pressure of SC-CO2 (10⿿30 MPa) on the esterification rate (X; %) and specific productivity (SP; kg of product/kg of catalyst x hour) were evaluated. A home-made high-pressure stirred-batch reactor (100 ml) was used in the experiments. The use of Novozym 435 achieved higher conversion and specific productivity of eugenyl acetate than Lipozyme 435. An excess of acetic anhydride (5:1 M/M) and high enzyme concentration (10%) achieved higher esterification rates than the lowest conditions (1% and 1:1 M/M). The optimal temperatures and pressure for the synthesis of eugenyl acetate in SC-CO2 were 50 and 60 °C at 10 MPa, respectively. The phase behavior of the reaction system and the synthesis in organic medium were also studied. Kinetic experiments performed at 40, 50 and 60 °C indicated that the reaction follows the simple Ping-Pong Bi-Bi mechanism and the affinity of acetic anhydride to enzyme was larger than that of eugenol.

Santolin, L., Fiametti, K. G., da Silva Lobo, V., Wancura, J. H., & Oliveira, J. V. (2021). Enzymatic synthesis of eugenyl acetate from essential oil of clove using lipases in liquid formulation as biocatalyst. Applied biochemistry and biotechnology, 193(11), 3512-3527.

Abstract. In this research, eugenyl acetate, a compound with flavoring, antioxidant, and antimicrobial properties, was obtained from essential oil of clove (Syzygium aromaticum) via liquid lipase-mediated acetylation. Clove essential oil was extracted by drag water vapor from dry flower buds and its physic-chemical characteristics were analyzed. For the enzymatic synthesis, an extensive evaluation of reaction parameters was accomplished through employment of distinct reaction temperatures, acetic anhydride to eugenol molar ratios, enzyme loads, and three different lipases (a lyophilized enzyme produced by solid-state fermentation of sunflower seed with Penicillium sumatrense microorganism and other two commercial lipases — Lipozyme TL 100L and CALB L). The product eugenyl acetate was confirmed by 1H-NMR, 13C-NMR Distortionless Enhancement by Polarization Transfer (DEPT 135), and Heteronuclear Multiple Bond Correlation (HMBC). Through optimized conditions (55 °C, acetic anhydride to eugenol molar ratio of 1:1, 10 wt% of Lipozyme TL 100L), 91.80% of conversion after 2 h was achieved to the eugenyl acetate production. With the results obtained, it was possible to conclude that the use of lipases in liquid formulation is a promising alternative for the synthesis of essential esters largely applied on food, cosmetic, and pharmaceutical industries.

dos Santos, A. L., Chierice, G. O., Alexander, K., & Riga, A. (2009). Crystal structure determination for eugenyl acetate. Journal of Chemical Crystallography, 39(9), 655-661.

Abstract. Essential oils are good candidates for the substitution of conventional medicinal treatments. Many articles and patents for their use have been published in recent years. The most attractive aspects of using essential oils as medicaments are their natural source and rapid permeability. Besides permeability, the solubility behavior of a drug is a key determinant of its oral bioavailability. Based on these characteristics, the aim of this study was to synthesize an essential oil derivative compound, using the raw oil extracted from Syzygium aromaticum L., without previous purification. The Eugenol molecular modification may diminish the problems of water solubility and bioavailability. The Eugenyl acetate molecule was characterized and its molecular modification investigated, including its structural properties and stereochemistry. This study was performed applying techniques, such as carbon-13 nuclear magnetic resonance spectroscopy (C-13 NMR), X-ray crystallographic analysis (XRD), powder X-ray diffraction (PXRD) and microscopic recording.