Compendium of the most significant studies with reference to properties, intake, effects.

Paoli L, Fačkovcová Z, Guttová A, Maccelli C, Kresáňová K, Loppi S. Evernia Goes to School: Bioaccumulation of Heavy Metals and Photosynthetic Performance in Lichen Transplants Exposed Indoors and Outdoors in Public and Private Environments. Plants (Basel). 2019 May 13;8(5):125. doi: 10.3390/plants8050125. 

Abstract. Recently indoor air quality (IAQ) has become a key issue, especially in schools, where children spend most of the day. Only in a few cases IAQ was investigated using lichens as biomonitors. During autumn 2017, lichens (Evernia prunastri) were exposed for two months indoors and outdoors in public (schools) and private (dwellings) environments, in both rural and urban areas of Slovakia. The bioaccumulation of selected elements and the physiological status of the samples were considered. The content of heavy metals increased in samples exposed outdoors for 11 out of 12 elements (Al, As, Cd, Cr, Cu, Fe, Pb, S, Sb, V and Zn, but not Ca) in the urban area and for 5 (As, Cd, Cu, Pb and Sb) in the rural area. Indoor concentrations were overall similar, both in rural and urban buildings, independently of the outdoor conditions. An indoor accumulation occurred only for Cd, Cu and Pb. An indoor origin was suggested for Cd, while for Cu and Pb, outdoor penetration (car traffic) is the likely cause of indoor values. Indoor exposed lichens maintained their vitality (as reflected by chlorophyll a fluorescence emission). This latter result further supports the use of lichen biomonitoring as a suitable method for assessing IAQ.

Calchera A, Dal Grande F, Bode HB, Schmitt I. Biosynthetic Gene Content of the 'Perfume Lichens' Evernia prunastri and Pseudevernia furfuracea. Molecules. 2019 Jan 8;24(1):203. doi: 10.3390/molecules24010203.

Abstract. Lichen-forming fungi produce a vast number of unique natural products with a wide variety of biological activities and human uses. Although lichens have remarkable potential in natural product research and industry, the molecular mechanisms underlying the biosynthesis of lichen metabolites are poorly understood. Here we use genome mining and comparative genomics to assess biosynthetic gene clusters and their putative regulators in the genomes of two lichen-forming fungi, which have substantial commercial value in the perfume industry, Evernia prunastri and Pseudevernia furfuracea. We report a total of 80 biosynthetic gene clusters (polyketide synthases (PKS), non-ribosomal peptide synthetases and terpene synthases) in E. prunastri and 51 in P. furfuracea. We present an in-depth comparison of 11 clusters, which show high homology between the two species. A ketosynthase (KS) phylogeny shows that biosynthetic gene clusters from E. prunastri and P. furfuracea are widespread across the Fungi. The phylogeny includes 15 genomes of lichenized fungi and all fungal PKSs with known functions from the MIBiG database. Phylogenetically closely related KS domains predict not only similar PKS architecture but also similar cluster architecture. Our study highlights the untapped biosynthetic richness of lichen-forming fungi, provides new insights into lichen biosynthetic pathways and facilitates heterologous expression of lichen biosynthetic gene clusters.

Munzi S, Cruz C, Maia R, Máguas C, Perestrello-Ramos MM, Branquinho C. Intra- and inter-specific variations in chitin in lichens along a N-deposition gradient. Environ Sci Pollut Res Int. 2017 Dec;24(36):28065-28071. doi: 10.1007/s11356-017-0378-3.

Abstract. The mechanisms of nitrogen (N) tolerance in lichens are not yet fully understood. Here, we investigated how the increase of chitin content is related with N excess at inter- and intra-specific levels, by using species with differing ecological N tolerances (the tolerant Xanthoria parietina and Parmotrema hypoleucinum and the sensitive Evernia prunastri and Usnea sp.) and thalli of X. parietina and P. hypoleucinum from sites with different availabilities of N of agricultural origin (livestock), as confirmed by lichen N content and δ¹⁵N. Nitrogen, chitin (N-containing compound), and ergosterol contents were measured in lichen thalli. Nitrogen and chitin contents were higher in tolerant species than those in sensitive ones (inter-specific level) and in thalli collected from the N-polluted site than in thalli from the clean site (intra-specific level). We suggest that chitin contributes to N stress tolerance in lichens, and that excess N can be partially stored as chitin (non-toxic form) in the cell walls of tolerant species.

Safety

Nardelli A, Drieghe J, Claes L, Boey L, Goossens A. Fragrance allergens in 'specific' cosmetic products. Contact Dermatitis. 2011 Apr;64(4):212-9. doi: 10.1111/j.1600-0536.2011.01877.x. 

Abstract.  Background: Together with preservative agents, fragrance components are the most important sensitizing culprits in cosmetic products. Objectives: To identify the nature of the fragrance ingredients responsible for allergic contact dermatitis (ACD) from specific cosmetic products. Methods: Between 2000 and 2009, positive patch test reactions or positive usage tests with the patients' own cosmetic products, were recorded using a standardised form. Results: Of the 806 cosmetic records, corresponding to 485 patient files, 344 concerned reactions to fragrance ingredients that according to the label were present ('Presence Confirmed' [PC n = 301]) or suspected to be present ('Presence Not Confirmed' [PNC n = 376]) in the causal cosmetic products used, which belonged to 15 different categories, toilet waters/fine perfumes being the most frequent. Geraniol in fragrance mix I (FM I) and hydroxyisohexyl 3-cyclohexene carboxaldehyde (HICC) in FM II were the most frequent PC, and together with hydroxycitronellal and Evernia prunastri (oak moss) the most frequent PNC ingredients in the causal cosmetic products. Limonene was the most frequent PC confirmed fragrance allergen. Conclusions: This study not only underlines the usefulness of fragrance-ingredient labelling in order to identify the causal allergen(s) present in specific cosmetic products, but may also provide information on trends in the actual use of sensitizing fragrance ingredients in them.

Vannini A, Jamal MB, Gramigni M, Fedeli R, Ancora S, Monaci F, Loppi S. Accumulation and Release of Mercury in the Lichen Evernia prunastri (L.) Ach. Biology (Basel). 2021 Nov 18;10(11):1198. doi: 10.3390/biology10111198.

Abstract. This study investigated the dynamics of the accumulation and release of Hg2+ in lichens, using Evernia prunastri (L.) Ach. as a model species. Thalli were incubated with solutions containing 1, 10, and 100 µM Hg2+ and then exposed for 1, 2, 3, 6, 12, 18, and 24 months at the Botanical Garden of the University of Siena (a location free from local Hg sources). Lichen samples accumulated Hg proportionally to the exposure concentration, and after the exposure, reductions over time were evident, already starting from 1-2 months. After 24 months, samples released 72-74 (healthy thalli) to 94% (unhealthy thalli) of the accumulated Hg, but control values of untreated samples were never reached. Depending on the Hg content after the exposure, stable decreased concentrations were reached after 6-24 months. The results of this study highlight the ability of the lichen E. prunastri to reflect rapidly increasing environmental Hg concentrations, as well as to indicate an ameliorated situation (e.g., the closure of an Hg source). However, we have found evidence that an acute pollution episode can influence the content of Hg in lichens for several years.

 Evernia prunastri extract (oakmoss)

Description
Evernia prunastri extract, commonly known as oakmoss, is obtained from a lichen that grows on the bark of oaks, beeches and other deciduous trees in cool, humid European regions. The extract is typically obtained as a resinoid, absolute or tincture, with colour ranging from dark green to brown and a very characteristic odour: woody, earthy, mossy, damp-forest, with leathery and slightly smoky nuances. It is a classic ingredient in perfumery, especially in chypre, fougère and woody compositions.

Common name: Oakmoss

Organism: Evernia prunastri (L.) Ach.

Kingdom: Fungi (functionally; lichens are symbiotic organisms)
Simbiosis between:

• a fungus (mycobiont, Ascomycetes)

• a green alga or cyanobacterium (photobiont)

Division (mycobiont): Ascomycota
Order: Lecanorales
Family: Parmeliaceae
Genus: Evernia
Species: Evernia prunastri

Note: Lichens are not plants but stable symbiotic organisms consisting of a fungus plus a photosynthetic partner that live as a single integrated system.

Cultivation and growth conditions

Because Evernia prunastri is an epiphytic lichen, it is not cultivated like agricultural crops. It grows naturally on the bark of trees—especially oak, but also fir and pine—in humid, unpolluted forest environments. Below are its ecological requirements.

Climate

Oakmoss thrives in:

• cool to temperate climates,

• areas with high atmospheric humidity,

• regions with mild summers and not overly harsh winters.

It is highly sensitive to air pollution (SO₂, nitrogen oxides), so it grows abundantly only where the air is clean.

Sun exposure

Prefers:

• filtered light or partial shade, typical of mixed forests,

• bark surfaces not exposed to intense direct sunlight.

Excessive sunlight can cause dehydration and slow down growth.

Substrate / Soil

As an epiphyte:

• it does not grow in soil,

• it grows on tree bark (especially oak),

• it is not parasitic—the bark is only a support surface.

Requires:

• untreated, naturally textured bark,

• slightly acidic surfaces.

Irrigation

It does not require irrigation. It absorbs water from:

• rain,

• fog,

• dew.

Extended periods of dryness slow down its metabolic activity.

Temperature

• Optimal growth: 5–18 °C

• Tolerates winter cold down to –10/–15 °C when desiccated

• Suffers in prolonged hot and dry conditions

Nutrition

Oakmoss does not absorb nutrients from the tree. It obtains:

• minerals and moisture from the atmosphere,

• carbon through photosynthesis carried out by the photobiont.

Because of this, it is an excellent bioindicator of air quality and disappears from polluted areas.

Crop care

In nature, it requires no management. To maintain or propagate it artificially:

• avoid pollutants and dry air,

• ensure diffused light and high humidity,

• avoid frequent handling (it is fragile).

Growth is extremely slow: only a few millimeters per year.

Harvest

Traditional harvesting occurs:

• by hand,

• from naturally fallen branches,

• or directly from trees (only where legally permitted).

After collection, oakmoss is:

• dried,

• aged for several weeks,

• extracted (mainly via solvents) to produce the well-known oakmoss absolute, widely used in perfumery.

Propagation

Reproduction is slow and complex, typical of lichens:

• natural fragmentation (small pieces re-grow),

• lichen propagules (soredia, isidia),

• spontaneous recolonization of new branches under ideal conditions.

There is currently no true large-scale agricultural cultivation of oakmoss.

Indicative nutritional values
Not applicable. This is a non-food ingredient intended exclusively for perfumery, cosmetics and fragrance applications.

Key constituents

• Polysaccharides (lichenan and related structural carbohydrates)

• Lichen acids (e.g. atranol, chloroatranol in traditional extracts; now strictly regulated and largely removed in purified qualities)

• Aromatic alcohols, aldehydes and esters contributing to odour profile

• Terpenoid compounds with fixative and olfactory functions

• Trace constituents that provide the typical mossy, damp, woody character

Production process

Harvesting

• Oakmoss is collected from tree bark in temperate forests.

• In many regions, collection is regulated to avoid overharvesting and to protect local ecosystems.

• Sustainable practice favours collection from fallen branches and controlled harvesting zones.

Extraction

• Dried lichen is macerated in suitable solvents (ethanol or other approved organic solvents) to produce:

  • Oakmoss resinoid

  • Oakmoss absolute (further purified from the resinoid)

  • Tinctures (low-concentration ethanolic extracts)

• The crude extract is filtered and concentrated under controlled conditions.

Standardisation / purification

• Cosmetic-grade extracts are often purified to drastically reduce allergenic lichen acids (especially atranol and chloroatranol).

• Specifications may include maximum allowed levels of these molecules according to current regulations.

Physical properties

• Form: viscous resinoid, waxy mass, or viscous liquid (absolute), or hydroalcoholic solution (tincture)

• Colour: dark green, olive, brownish or nearly black

• Odour: very intense, mossy, woody, earthy, slightly leathery and damp

• Solubility:

  • Good in ethanol and many perfume bases

  • Very limited in water

• Stability: good if stored away from light, heat and air; sensitive to oxidation over long periods

Sensory and technological properties

• Functions primarily as a base note and fixative in fragrances.

• Adds depth, roundness and natural “forest floor” character to perfume accords.

• Enhances longevity and diffusion of other fragrance components, especially floral, woody and citrus notes.

• Key material for constructing traditional chypre and fougère accords, often combined with bergamot, patchouli, labdanum and woods.

Uses (non-food)

• Fine perfumery (eau de parfum, parfum, colognes)

• Fragranced cosmetics (creams, lotions, aftershaves) within regulatory limits

• Soaps and shower products (especially traditional bar soaps)

• Home fragrances (candles, room sprays, diffuser concentrates), subject to IFRA-type restrictions

Nutrition & health
Not applicable to dietary use (not intended for ingestion).

From a dermal perspective:

• Oakmoss components, especially atranol and chloroatranol in unpurified extracts, are strong skin sensitisers.

• Modern cosmetic use relies on allergen-reduced or “low-atranol” oakmoss, applied at very low dosage and under strict regulatory conditions.

Portion note
Not applicable to food.
Typical use concentrations in finished cosmetic or fragrance products are very low (often well below 0.1%, and lower still for leave-on skin products, depending on regulatory and IFRA guidance).

Allergens and sensitisation

• Traditional oakmoss extracts contain potent fragrance allergens (especially atranol and chloroatranol), strongly associated with contact allergy.

• Modern regulations require use of purified extracts with extremely low levels of these substances.

• Even with purified grades, oakmoss-type ingredients are used at restricted levels and require careful safety evaluation in finished products.

Storage and shelf-life

• Store in tightly closed containers, protected from light and heat.

• Recommended storage: cool, dry environment (often in amber glass or coated metal containers).

• Typical shelf-life: 24–36 months under proper storage, with periodic control of odour profile and colour.

• Avoid prolonged exposure to air, which can lead to oxidation and potential change in odour profile.

Safety and regulatory aspects

• In the EU and many other regions, oakmoss is one of the most strictly regulated fragrance ingredients.

• Use of non-purified extracts with significant atranol and chloroatranol content is essentially prohibited in cosmetics.

• Only purified oakmoss extracts with very low allergen content are allowed, at restricted maximum concentrations and typically in certain product types only.

• Manufacturers must apply GMP and carry out safety assessments, often using up-to-date IFRA standards and cosmetic regulations as reference.

Labelling

• INCI name: Evernia Prunastri Extract (for cosmetic ingredient lists).

• Finished products must list all regulated fragrance allergens above their respective thresholds according to cosmetic law (e.g. on the INCI list).

• Additional information may include:

  • Batch or lot number

  • Best-before or production date

  • Storage recommendations

  • Indication of “low-atranol” or purified quality where relevant (in technical documentation/COA rather than on consumer label).

Troubleshooting

• Overpowering, “muddy” base note → dosage too high; adjust level or use more purified/rectified qualities.

• Colour darkening in formula → potential oxidation or interaction with other ingredients; review antioxidants and packaging.

• Skin irritation or sensitisation reports → review extract specification (atranol/chloroatranol content), total allergen load in formula and overall dosage; may require reformulation.

• Incomplete solubility in alcohol → check grade and solvent ratio; gently warming and proper pre-dilution can help.

Sustainability and supply chain

• Evernia prunastri grows slowly; overharvesting can damage forest ecosystems.

• Sustainable sourcing includes:

  • Controlled quotas and regulated harvesting zones

  • Preference for lichen collected from fallen branches or pruning waste

  • Supplier certification and traceability schemes

• Development of biotechnological, synthetic or nature-identical alternatives aims to reduce pressure on wild resources while reproducing oakmoss odour profiles.

Main INCI functions (cosmetics)

• Fragrance (Aromatic) – characteristic mossy-woody note in perfumes and fragranced products.

• Fixative – helps prolong the persistence of volatile notes.

• Masking agent – can help mask undesirable base odours of raw materials in complex formulations.

All uses must comply with current cosmetic regulations and safety assessments.

Conclusion
Evernia prunastri extract (oakmoss) is a historically iconic material in perfumery, prized for its deep, mossy, woody character and strong fixative power. Due to its high allergenic potential in traditional forms, modern cosmetic and fragrance use is limited to purified, low-allergen grades and strictly controlled dosage levels. When responsibly sourced and correctly purified, oakmoss remains a unique and valuable building block for chypre, fougère and woody accords, adding complexity, depth and lasting character to fragrances.

Mini-glossary

• GMP – Good Manufacturing Practices; quality and hygiene standards for production.

• HACCP – Hazard Analysis and Critical Control Points; preventive safety system (more typical for food, but the concept of risk analysis is also relevant to cosmetic production).

• INCI – International Nomenclature of Cosmetic Ingredients; standard naming system for cosmetic ingredient labelling.

• Allergen-reduced / low-atranol – Oakmoss extract quality specifically purified to minimise atranol and chloroatranol content and reduce sensitisation risk.

Studies

Data obtained from this study clearly showed that Evernia prunastri methanol extract has significant anti-cancer effects that are believed to be partly due to antioxidant activity and the ability to induce antioxidants Evernia prunastri methanol extract. This is the first report indicating the anti-genetossic activities of Evernia prunastri methanol extract against various mutagenic agents (1).

This study evaluated for the first time the in vitro cytoprotective properties, based on the antioxidant activities, of the Parmeliaceae lichens Evernia prunastri and Usnea ghattensis and the mechanism of action of their major phenolic constituents: the evernic and usnic acids, respectively. In two models of central nervous system (2).

As with lichens in general, the antifungal and anti-biofilm activity of Evernia prunastri has also been confirmed (3).

Cosmetics

It is a fragrance inserted to impart a scent of mistletoe or tree. Unfortunately, it contains a known allergen:  Chloroatranol (3-Chloro-2,6-dihydroxy-4-methylbenzaldehyde). 

Safety

The patch tests with the mixes containing Evernia prunastri (oak moss) with a high content of chloratranol/atranol resulted in substantially more positive reactions than the corresponding tests with the mixes containing oak moss with a low content of chloratranol/atranol (4).

The most relevant studies on the subject have been selected with a summary of their contents:

Evernia prunastri studies

References___________________________________________________________________

(1) Alpsoy L, Orhan F, Nardemir G, Agar G, Gulluce M, Aslan A. Antigenotoxic potencies of a lichen species, Evernia prunastri. Toxicol Ind Health. 2015 Feb;31(2):153-61. doi: 10.1177/0748233712469655. 

(2) Fernández-Moriano C, Divakar PK, Crespo A, Gómez-Serranillos MP. Protective effects of lichen metabolites evernic and usnic acids against redox impairment-mediated cytotoxicity in central nervous system-like cells. Food Chem Toxicol. 2017 Jul;105:262-277. doi: 10.1016/j.fct.2017.04.030. 

(3) Millot M, Girardot M, Dutreix L, Mambu L, Imbert C.  Antifungal and Anti-Biofilm Activities of Acetone Lichen Extracts against Candida albicans.    Molecules. 2017 Apr 19;22(4). pii: E651. doi: 10.3390/molecules2204065

Abstract. Candida albicans is a commensal coloniser of the human gastrointestinal tract and an opportunistic pathogen, especially thanks to its capacity to form biofilms. This lifestyle is frequently involved in infections and increases the yeast resistance to antimicrobials and immune defenses. In this context, 38 lichen acetone extracts have been prepared and evaluated for their activity against C. albicans planktonic and sessile cells. Minimum inhibitory concentrations of extracts (MICs) were determined using the broth microdilution method. Anti-biofilm activity was evaluated using tetrazolium salt (XTT) assay as the ability to inhibit the maturation phase (anti-maturation) or to eradicate a preformed 24 h old biofilm (anti-biofilm). While none of the extracts were active against planktonic cells, biofilm maturation was limited by 11 of the tested extracts. Seven extracts displayed both anti-maturation and anti-biofilm activities (half maximal inhibitory concentrations IC50_mat and IC50_biof ≤ 100 µg/mL); Evernia prunastri and Ramalina fastigiata were the most promising lichens (IC50_mat < 4 µg/mL and IC50_biof < 10 µg/mL). Chemical profiles of the active extracts performed by thin layer chromatography (TLC) and high performance liquid chromatography (HPLC) have been analyzed. Depsides, which were present in large amounts in the most active extracts, could be involved in anti-biofilm activities. This work confirmed that lichens represent a reservoir of compounds with anti-biofilm potential.

 (4) Bruze M, Mowitz M, Ofenloch R, Coenraads PJ, Diepgen TL, Elsner P, Gonçalo M, Naldi L, Svensson Å. The significance of batch and patch test method in establishing contact allergy to fragrance mix I-EDEN Fragrance Study Group. Contact Dermatitis. 2019 Aug;81(2):104-109. doi: 10.1111/cod.13253.