pediaRosemary oil, Rosmarinus officinalis L. (Lamiaceae family — in current nomenclature Salvia rosmarinus Spenn.) is an aromatic essential oil obtained through steam distillation of the leafy branches of the plant. The name derives from the Latin words "ros marinus" (sea dew). A common ingredient in Mediterranean cuisine and modern cosmetics, rosemary is particularly investigated in the antioxidant and antimicrobial contexts in cosmetic and food literature. This monograph addresses rosemary oil as a cosmetic ingredient; it carries no claim of treatment or healing. In particular, the antioxidant potential of carnosic acid and carnosol diterpenes has attracted significant interest in the food and cosmetic industries.
This article is not a product promotion. Its aim is to provide an independent framework on the position of rosemary oil in scientific literature. The information presented herein contains no claim of treatment.
Botanical source and history
Rosmarinus officinalis L. (current: Salvia rosmarinus Spenn.) is an evergreen, aromatic shrub native to the Mediterranean basin. It can reach 1-2 meters in height; its narrow, needle-like leaves are dark green, with silvery-white undersides. Its pale blue-purple flowers are an important nectar source for bees.
The cultural history of rosemary is extremely rich. In ancient Greece, students would carry a sprig of rosemary or wear a rosemary crown during exams — it was believed that the plant strengthened memory and concentration. Shakespeare has Ophelia say to Hamlet "rosemary for remembrance." In ancient Rome it was used at weddings, funerals, and religious rituals. In medieval Europe, rosemary branches were burned during plague outbreaks in attempts to "purify" the air.
In Turkey, rosemary grows naturally along the Aegean and Mediterranean coasts. It is found in both wild and cultivated forms in the regions of Mersin, Antalya, Muğla, and Izmir. Turkey's export potential for rosemary essential oil is steadily increasing.
Chemical profile and chemotypes
Rosemary oil is one of the finest examples of the "chemotype" concept in plant chemistry. The chemical composition of oil obtained from the same plant species varies dramatically according to geographic location and climatic conditions. For this reason, rosemary oil is divided into three main chemotypes:
1,8-Cineole chemotype (ct. cineole)
Main component: 1,8-cineole (eucalyptol) 38-55%. Fresh, refreshing, eucalyptus-like odor. The most commonly preferred chemotype in cosmetic use. Widespread in North Africa (Morocco, Tunisia) and some Mediterranean regions.
Camphor chemotype (ct. camphor)
Main component: camphor 15-25%. Sharp, camphoraceous, medicinal odor. Widespread in Spain. Caution is required in cosmetic use due to potential neurotoxicity — use is not recommended in epilepsy patients, pregnant women, and young children.
Verbenone chemotype (ct. verbenone)
Main component: verbenone 15-37%. Soft, herbaceous, slightly sweet odor. Widespread on the island of Corsica in France. The rarest and most expensive chemotype. Preferred in skincare because of lower camphor content.
Other important components
Common components in all three chemotypes: α-pinene (5-25%), camphene (2-8%), β-pinene, borneol, bornyl acetate, limonene, and myrcene. In the leaf (not in essential oil, but in extract form), strong diterpene and phenolic antioxidants such as carnosic acid, carnosol, and rosmarinic acid are present.
Position in scientific literature
Antioxidant research: carnosic acid and carnosol
Rosemary's antioxidant capacity is associated primarily with carnosic acid and carnosol from leaf diterpenes. These compounds are used as natural antioxidants in the food industry — rosemary extract (E 392) is approved as a food additive in EU regulations. In in vitro studies, carnosic acid has demonstrated antioxidant activity comparable to synthetic antioxidants BHA and BHT and equivalent to vitamin E (α-tocopherol).
Scientific literature — scope note
Rosemary oil has also been investigated in dermatology and hair-care literature; however, these medical/clinical uses (e.g., hair loss research) belong to the context of pharmaceutical products and fall outside the scope of this cosmetic ingredient monograph. In this monograph, rosemary oil is addressed in the context of its chemical profile and cosmetic (fragrance, antioxidant) uses.
Antimicrobial properties
Rosemary essential oil has demonstrated antimicrobial activity against various gram-positive and gram-negative bacteria, fungi, and some foodborne pathogens in in vitro studies. In a review published in the Medicines journal by Nieto and colleagues (2018), the antimicrobial and antioxidant properties of rosemary were comprehensively evaluated. 1,8-cineole and α-pinene were identified as the primary contributors to antimicrobial activity.
Safety profile
General assessment
Rosemary oil is generally safe in cosmetic use at low concentrations (1-3%) in the 1,8-cineole and verbenone chemotypes. The CIR panel has evaluated rosemary oil as safe in cosmetic products.
Chemotype-dependent cautions
The camphor chemotype requires special attention due to potential neurotoxicity. High camphor concentration may carry a risk of convulsion. Use of the camphor chemotype is not recommended in epilepsy patients, pregnant women, nursing mothers, and children under 6 years old. The 1,8-cineole chemotype has a safer profile and is preferred in cosmetic applications.
Allergen notification
The limonene and linalool found in rosemary oil are among the components requiring allergen notification in the EU Cosmetics Regulation.
Rosemary oil in soap making
Use as an essential oil
Rosemary oil is added to soap at the trace stage at a rate of 3-5%. It imparts a "fresh, herbaceous, camphoraceous, refreshing" fragrance profile to the soap. The 1,8-cineole chemotype is the most preferred type in soap making.
Compatible blends
Rosemary oil creates very compatible blends with other essential oils: with lavender "herbaceous-aromatic," with eucalyptus "refreshing," with peppermint "invigorating," with tea tree "clean-herbaceous," and with lemon "fresh-energetic" combinations are the most classic examples.
ROE: as a natural antioxidant
Another important use of rosemary in soap making is its addition to the recipe as a natural antioxidant. ROE (Rosemary Oleoresin Extract) is a concentrated extract obtained from rosemary leaves and is rich in carnosic acid / carnosol. It is used in soap formulas to delay oxidation of other oils (particularly those high in linoleic acid) and prevent the formation of DOS (dreaded orange spots). It is common practice to add a few drops of ROE per 500 grams of oil.
Frequently asked questions
What is rosemary oil?
Rosemary oil is an aromatic essential oil obtained through steam distillation of the leafy branches of the Rosmarinus officinalis plant. Three chemotypes are present: 1,8-cineole, camphor, and verbenone.
Which chemotype of rosemary oil is used in soap?
In soap making, the 1,8-cineole chemotype is generally preferred — due to its fresh-refreshing fragrance and safer profile. The camphor chemotype requires caution in cosmetic use due to potential neurotoxicity.
What does rosemary oil do in soap?
It imparts a fresh, herbaceous fragrance to the soap at a rate of 3-5%. Additionally, its ROE form acts as a natural antioxidant, delaying oxidation of other oils in the soap and preventing the formation of DOS.
What is the difference between rosemary oil chemotypes?
The 1,8-cineole chemotype is fresh-refreshing in odor and the safest; the camphor chemotype is sharp-medicinal in odor but carries neurotoxicity risk; the verbenone chemotype is soft-herbaceous in odor, rarest, and most expensive. The 1,8-cineole chemotype is preferred in cosmetics.
Chailea products containing this ingredient
- Natural Rosemary Soap 100 g
References
1. Nieto G, Ros G, Castillo J. Antioxidant and Antimicrobial Properties of Rosemary (Rosmarinus officinalis L.): A Review. Medicines, 2018; 5(3):98. PMID: 30181448. PubMed.
3. Borrás-Linares, I., et al. (2014). Rosemary (Rosmarinus officinalis) diterpenes. Journal of Chromatography A.
4. EU (2010). Commission Regulation (EU) No 231/2012 — E 392 Rosemary extracts.