🌿 Aromatic Plants

SWEET BASIL Ocimum basilicum L.

Key Properties

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🌿 Sweet basil 🌿 ISO standard for basil oil 🌿 Composition of basil oils 🌿 Accessions and cultivars 🌿 Egyptian basil leaves 🌿 Methyl chavicol (estragole) 🌿 Estragole 🌿 Toxicological assessments 🌿 IFRA standard 🌿 EU law 🌿 References
Introduction
Sweet basil

Species

BinomialOcimum basilicum
Accepted nameOcimum basilicum L.
POWO statusaccepted
FamilyLamiaceae
IPNI identifierurn:lsid:ipni.org:names:452874-1

Source: Govaerts R. (ed.), World Checklist of Vascular Plants (WCVP), Royal Botanic Gardens, Kew, accessed on 21/09/2026.

Which plant is sweet basil?

In the World Checklist of Vascular Plants (WCVP, Kew), in the extract read on 21/09/2026, the name with identifier 136820, of rank “Species” and placed in the family Lamiaceae, has the status “Accepted”: Ocimum basilicum L.

In the WCVP extract read on 02/10/2026, Ocimum × citriodorum Vis. has the status “Synonym” and is attached to the accepted name with identifier 136798, Ocimum × africanum Lour. (Ocimum × citriodorum in the article cited below), of status “Accepted”.

Is there an ISO standard for basil oil?

According to the ISO catalogue record, ISO 11043:1998 is titled “Oil of basil, methyl chavicol type (Ocimum basilicum L.)”. The same record gives ISO 11043:1998 the status “Published”, the publication date 1998-10, the stage “International Standard confirmed” (90.93), edition 1, 5 pages, and places it under technical committee ISO/TC 54. The record states that the standard was last reviewed and confirmed in 2026, and concludes that this version remains current.

How does the composition of basil oils vary, according to the literature?

Citing other work, da Costa and colleagues (2015) write that despite the wide variation in the chemical composition of basil essential oil within the same species, monoterpenes and phenylpropanoids predominate.

Citing other work, the same authors state that the presence of methyl chavicol in basil essential oil has been reported in genotypes from Yemen, the USA, Thailand, the United Kingdom and Brazil, and in local varieties from Turkey. Citing an earlier reference, Chenni and colleagues (2016) describe a classification of basil oils into four chemotypes by chemical composition and geographical source: a European type (cultivated in Europe, the USA and Africa) characterised by linalool and methyl chavicol as major constituents; a Reunion type (Comoros, Seychelles, Africa, Reunion Island) characterised by a high concentration of methyl chavicol; a tropical type (India, Pakistan, Guatemala, Haiti, Africa) rich in methyl cinnamate; and a chemotype with eugenol as the main component, common in North Africa, Russia, Eastern Europe and parts of Asia.

What did a study of 31 accessions and seven cultivars report?

da Costa and colleagues (2015) set out to chemically characterise 31 accessions and seven cultivars of basil, and based the percentage composition of their essential oils on the 14 most abundant constituents: 1,8-cineole, linalool, methyl chavicol, neral, nerol, geraniol, geranial, methyl cinnamate, β-bourbonene, methyl eugenol, α-trans-bergamotene, germacrene-D, epi-α-cadinol and δ-cadinene.

According to the authors, a randomised complete block design with two replications was used to evaluate 38 genotypes that the text names as O. basilicum (“38 genotypes of O. basilicum”): 31 accessions provided by the North Central Regional PI Station (Iowa State University, USA) and seven commercial cultivars donated by the companies Topseed and Johnny’s Selected Seeds. In Table 1 of the study, the cultivar “Sweet Dani” (Johnny’s Selected Seeds Co) is attributed to Ocimum x citriodorum.

Three months after cultivation, the plants were harvested and the leaves dried in an air-circulation oven at 40 °C for five days; the essential oil of the dried leaves was extracted by hydrodistillation in a Clevenger-type apparatus for 160 minutes, with 50 g of dry leaves per flask, then analysed by GC-MS on a Shimadzu QP5050A system.

Which constituents dominated in this study?

In this study, linalool was the main constituent of the essential oil of most accessions and cultivars; in the cultivars “Genovese”, “Fino Verde”, “Red Rubin” and “Osmin Purple” and in the accessions NSL6421, PI 197442, PI 358464, PI 368698 and PI 414194, the linalool concentration was over 60 %. The accessions PI 414196, PI 176 646, PI 211586, PI 414193 and PI 414198 showed epi-α-cadinol levels above 30 %, accession PI 358466 contained 46 % geraniol and accession PI 172996 45 % methyl chavicol. In the cluster analysis, cluster 7 grouped the accessions PI-172996, PI-207498, PI-296391, PI-172997, PI-296390, PI-253157 and PI-368697, with linalool and methyl chavicol as the major compounds. The cultivar “Cinnamon” stood out for its methyl cinnamate concentration (31 %), a constituent present in only three accessions and always below 6 %. The authors observed that compounds such as linalool, geraniol, methyl cinnamate, geranial, neral, methyl chavicol and epi-α-cadinol exceeded 30 % in some of the accessions and cultivars.

What did a study of Egyptian basil leaves report?

Chenni and colleagues (2016) studied purchased broken leaves of sweet basil (“Sweet basil broken leaves”, humidity 9.4 % ± 0.4 %) of Ocimum basilicum collected in Egypt in 2011 (n° 28587). For hydrodistillation, 150 g of the plant material immersed in 6 L of water were distilled in a Clevenger-type apparatus for 1 h, until no more essential oil was obtained, and the oil was dried over anhydrous sodium sulfate and stored at 4 °C. Solvent-free microwave extraction (SFME) was run at atmospheric pressure with 150 g of the plant material immersed in 600 g of water for 30 min at 600 W, heating being continued at 100 °C until no more essential oil was obtained.

What yield and composition did the two methods give?

According to the authors, 30 min of SFME gave yields (0.48 % ± 0.02 %) similar to those obtained after 60 min of hydrodistillation. Analysed by GC and GC-MS, the oils showed 65 compounds making up 99.3 % (SFME) and 99.0 % (hydrodistillation) of the oil, the main components being linalool (43.5 % SFME; 48.4 % HD), followed by methyl chavicol (13.3 % SFME; 14.3 % HD) and 1,8-cineole (6.8 % SFME; 7.3 % HD). In Table 2 of the study, methyl eugenol accounts for 3.7 % ± 0.1 in the hydrodistilled oil and 6.1 % ± 0.1 in the SFME oil. The authors observed no significant difference between the physical constants of the oils obtained by the two methods, the only difference being the lighter colour of the SFME oil. Comparing their results with other countries, the authors write that the observed difference in the constituents of basil oils “may” probably be due to environmental conditions and genetic factors, different chemotypes and the nutritional elements of the plants, as well as other factors that can influence oil composition.

How much methyl chavicol (estragole) do the sources report?

The figures below come from different studies and compilations; they are set side by side, not reconciled.

In the Egyptian leaf oils of Chenni and colleagues (2016), methyl chavicol accounted for 13.3 % (SFME) and 14.3 % (hydrodistillation). In the study of da Costa and colleagues (2015) described above, accession PI 172996 contained 45 % methyl chavicol. Table 1 of the HMPC public statement on estragole (EMA, 2023), presented as examples of the occurrence of estragole in plants and/or essential oils, lists Ocimum basilicum (“Sweet basil”) with 0.8 % essential oil in the herb, 20 to 89 % estragole in the essential oil, and approximately 0.4 % estragole in the part of the plant used. According to note 2 of that table, the compilation originates mainly from the food sector and is partially based on older publications whose cited original data are no longer (completely) publicly available. The 2025 EFSA FEEDAP opinion on a basil leaf tincture reports that the EFSA Compendium of botanicals lists, as substances of “potential concern” for human and animal health, 1,8-cineole (3.74 %–16.7 %), camphor (1.2 %), α-selinene (1.67 %), β-selinene (1.04 %), eugenol (1.4 %–10.3 %), estragole (2.4 %–16.5 %) and methyleugenol (0.5 %–1.6 %) in the essential oil of the aerial parts of Ocimum basilicum. The same opinion states that other publications reported thujones (0.001 %–14.84 %), safrole (0.1 %) and coumarin (0.12 %–0.37 %) in essential oils and other preparations from the leaves of Ocimum basilicum.

What is estragole?

According to the HMPC public statement (EMA, 2023), estragole (1-allyl-4-methoxybenzene, CAS 140-67-0, molecular mass 148.20 g/mol) is a volatile phenylpropanoid belonging to the alkenylbenzenes, like eugenol, isoeugenol, methyleugenol, safrole, isosafrole, anethole, elemicin, myristicin and apiole. The IFRA Standard “Estragole” (Amendment 51, 2023) covers CAS numbers 140-67-0, 1407-27-8 and 77525-18-9, and its synonyms include “Methyl chavicol”. In the ECHA CHEM database (search for CAS 140-67-0, read on 02/10/2026), the substance with identifier 100.004.935 is named “4-allylanisole”, with EC number 205-427-8, CAS number 140-67-0, IUPAC name “1-methoxy-4-(prop-2-en-1-yl)benzene” and molecular formula C10H12O. In the same response, the names attached to this record include “Estragole”, “Basil essential oil”, “Basil oil” and “4-allylanisole”, and its trade names include “Methyl chavicol (Estragole)”, “BASIL OIL (CHEMOTYPE ESTRAGOLE)” and “OCIMUM BASILICUM OIL”. The HMPC public statement states that estragole is a major or minor component of a large number of plants or plant parts used for herbal medicinal products, botanicals and flavourings, and that many of these plants contain other alkenylbenzenes or other components which “may” affect the kinetics or dynamics of estragole.

What do toxicological assessments report about estragole?

The document EMA/HMPC/137212/2005 Rev 1 Corr 1, dated 12 May 2023, is the public statement of the EMA Committee on Herbal Medicinal Products (HMPC) titled “Public statement on the use of herbal medicinal products containing estragole”.

What did earlier assessments conclude?

The public statement recalls that the HMPC had concluded, on the basis of the toxicological data available, that estragole is a naturally occurring genotoxic carcinogen with a DNA potency similar to safrole, and that metabolic activation and DNA binding also occur in human experimental systems. It reports that the Scientific Committee on Food (SCF, 2001) concluded that estragole is both genotoxic and carcinogenic. It reports that the Joint FAO/WHO Expert Committee on Food Additives (JECFA, 2009) evaluated a group of allyl alkoxybenzenes including estragole, present in food and essential oils and used as flavouring agents, and concluded that the data on the six alkoxy-substituted allylbenzenes provide evidence of toxicity and carcinogenicity in rodents given high doses, for several of these substances.

What do animal studies show?

According to the public statement, rats given 4 daily doses of 605 mg estragole/kg body weight showed liver injury on gross examination (Taylor and colleagues, 1964), and in the National Toxicology Program study (Bristol, 2011) female mice given 600 mg estragole/kg body weight died during week 1 from liver necrosis. On the basis of acute and sub-chronic studies, the statement names the liver as the principal target organ in both rats and mice. In the 3-month NTP study (Bristol, 2011), two of 10 male rats at 600 mg/kg had multiple cholangiocarcinomas of the liver and a third a hepatocellular adenoma, findings the NTP authors regarded as significant evidence of the carcinogenicity of estragole when all associated evidence, including other NTP studies on alkenylbenzenes, was taken into account. In the early studies of the Millers’ laboratory (Drinkwater and colleagues, 1976; Miller and colleagues, 1983; Wiseman and colleagues, 1987), estragole, its natural metabolites including hydroxyestragole, or synthetic derivatives, given to adult or newborn mice of different strains, produced hepatocellular carcinomas. The statement notes that no human studies are available on carcinogenicity. It also states that no data on reproductive toxicity and teratogenicity of estragole are available.

What do genotoxicity tests show?

Mutagenicity tests of estragole on Salmonella typhimurium were generally negative, “likely” because of the complex metabolism required for bioactivation in vivo, according to the statement. Martins and colleagues (2012) assessed the genotoxicity of estragole on V79 cells, and their results “suggest” that estragole, besides being metabolised to genotoxic metabolites, “may” also be a weak direct-acting genotoxin forming DNA adducts. The statement describes estragole as clearly genotoxic in transgenic mouse and rat strains (Suzuki and colleagues, 2012a, b). In the in vivo mouse micronucleus test (Bristol, 2011), no increase in the frequency of micronucleated normochromatic erythrocytes was observed in the peripheral blood of male and female mice of the 3-month study. Table 3 of the statement records that micronucleus tests are consistently negative, but “may not be appropriate” for detecting short-lived reactive metabolites in the liver.

What does the statement conclude on the mode of action?

On the basis of mode-of-action considerations, the statement describes estragole as a genotoxic hepatocarcinogen, DNA adduct formation being the first pre-initiation step. Although there have been no convincing reports of estragole hepatocarcinogenicity in rats, a study by Suzuki and colleagues (2012a) “suggests a possible involvement” of genotoxic mechanisms, and according to these results estragole “could be a possible” genotoxic hepatocarcinogen in the rat, at least at high doses. The statement considers the metabolic activation pathway and DNA adduct formation amply demonstrated in animals, the same pathway being operative in human in vitro systems, and therefore judges the mode of action for tumour formation relevant for humans. Its weight-of-evidence summary (Table 3) records clear evidence of carcinogenicity in mice, “Suggestive, but indirect” evidence in rats, and concludes that estragole is a genotoxic carcinogen in rodents. The same table notes that closely related alkenylbenzenes are animal genotoxins and carcinogens (safrole and methyleugenol: IARC class 2B).

Does the rest of basil oil change the picture?

The statement reports that Müller and colleagues (1994) showed that the “genotoxic potential” of estragole is not masked by the ingredients of basil oil: in the UDS test, with a basil oil containing 88 % estragole, basil oil induced UDS in the same dose range as estragole. It also reports that Rietjens’s group has in vitro evidence of inhibition of sulfoconjugation by constituents of basil extract, nevadensin being the most potent, and that in vivo results “suggest” that the likelihood of bioactivation and adverse effects in rodent bioassays “may” be lower when estragole is dosed with nevadensin than when pure estragole is dosed.

What did EFSA find in a basil leaf tincture?

In the basil tincture assessed by the EFSA FEEDAP Panel (2025), obtained from dried leaves of Ocimum basilicum, trace concentrations of methyleugenol (up to 0.0006 %) and estragole (up to 0.00005 %), two compounds with experimentally proven genotoxic and carcinogenic activities, were detected in all batches of the additive. The same opinion states that methyleugenol and estragole belong to the group of p-allylalkoxybenzenes and are genotoxic and carcinogenic.

Which IFRA standard applies to estragole?

In the IFRA standards library (search “estragole”, read on 02/10/2026), one entry carries CAS numbers 140-67-0, 1407-27-8 and 77525-18-9, the title “Estragole”, type “R”, publication date 2023-06 and amendment 51. The IFRA Standard “Estragole” is dated 2023 (Amendment 51) and mentions earlier publications in 2009, 2015 and 2020. Its recommendation is of the “RESTRICTION” type, and the intrinsic property driving risk management is “DERMAL SENSITIZATION AND SYSTEMIC TOXICITY”. The maximum acceptable concentrations of estragole in the finished product it sets are, by category: 1: 0.00031 %; 2: 0.0025 %; 3: 0.00063 %; 4: 0.014 %; 5A: 0.0022 %; 5B: 0.00063 %; 5C: 0.00063 %; 5D: 0.00021 %; 6: 0.0019 %; 7A: 0.00063 %; 7B: 0.00063 %; 8: 0.00021 %; 9: 0.0041 %; 10A: 0.00094 %; 10B: 0.0022 %; 11A: 0.00021 %; 11B: 0.00021 %; 12: 0.11 %. According to the standard, the Expert Panel for Fragrance Safety reviewed all the available data on estragole and recommends these concentrations for the 12 product categories as the maximum acceptable concentrations. Its implementation dates are 30 March 2024 for new creations and 30 October 2025 for existing creations, and apply to the supply of fragrance mixtures (formulas) only.

What does EU law say?

In the original text of Regulation (EC) No 1223/2009 on cosmetic products, Annex III, the list of substances which cosmetic products must not contain except subject to the restrictions laid down, includes linalool (CAS 78-70-6, EC 201-134-4), whose presence must be indicated in the list of ingredients when its concentration exceeds 0.001 % in leave-on products and 0.01 % in rinse-off products.

References