Material guide: basil oil — the word anisic in the odor family field is the chemotype's signature

About a 5 minute read.

Too long, didn't read

• Name: ocimum basilicum herb oil (sweet basil oil), CAS 8015-73-4, FEMA 2119
• 110 suppliers; the regulatory field reads FEMA GRAS only, and it is not FCC listed
• Odor family anisic; descriptors: basil, anise, herbal, tarragon, green, spicy
• Twelve records share this CAS, splitting three ways by odor family: anisic 6, licorice 4, herbal 1
• GHS: H227 combustible, H302 harmful if swallowed, H315 skin irritation, H319 eye irritation, H335 respiratory irritation. Nothing about genotoxicity
• Shelf life 24 months, specific gravity 0.890–0.930, optical rotation −5 to −15

That one word in the odor family field is the answer

Start with the odor family this database gives the oil: anisic. The odor field opens with basil, then anise, then herbal, then tarragon.

If you have smelled a fresh sweet basil leaf, that smell is bright, with a little mint and clove sweetness in it. Anise and tarragon are a different thing. That is the smell of methyl chavicol, otherwise known as estragole.

Which means this record is not describing "the smell of basil". It is describing the smell of a methyl chavicol chemotype basil oil. The odor family is not just a classification label here, it is the chemotype's signature.

Estragole is also a material in its own right in this database: 47 suppliers, odor family likewise anisic, longevity 8 hours.

One CAS, twelve records, three odor families

CAS 8015-73-4 carries twelve records. The eleven with an odor family split three ways:

Odor family	Records	What it means
anisic	6	methyl chavicol dominant
licorice	4	the same direction, licorice is the same signal
herbal	1	the linalool side

Sorted by supplier count:

Record	Suppliers	Odor family	First descriptors
ocimum basilicum herb oil	110	anisic	basil, anise, herbal, tarragon
ocimum basilicum herb oil egypt	31	anisic	sweet, herbal, tarragon, green, leafy
sweet basil absolute	20	herbal	herbal, green, leafy, sweet, spicy
ocimum basilicum herb oil vietnam	17	licorice	anise, herbal, tarragon, green
ocimum basilicum leaf oil india	13	anisic	sweet, herbal, tarragon, green

Egypt, Vietnam and India, one record each, all under the same CAS. This is the shape covered in a natural oil is not one molecule, and basil is one of its most extreme cases.

The interesting part is that the source data knows. The oil's solubility field has supplier odour-sample notes mixed into it, and among them are Lemon basil CT Citral and Sweet Basil CT Linalool Oil. CT is short for chemotype. Whoever wrote the catalogue knew chemotypes exist, and that information never reached a searchable field. It ended up at the tail of a solubility string.

One field in Mississippi, 38 accessions, seven chemotypes

In 2008 Zheljazkov and colleagues at Mississippi State ran an experiment that pins the variables down (PMID 18072735): 38 sweet basil accessions grown in a single field.

Same species, same location, same season, so what is left is genetics. The results:

• Oil content ranged from 0.07% to 1.92% of dry herbage, a 27-fold spread
• On composition, the accessions fell into seven chemotype groups
• High-linalool chemotype: 19–73% (−)-linalool
• Methyl chavicol chemotype: six accessions, 20–72% methyl chavicol
• Methyl eugenol–linalool chemotype: two accessions, methyl eugenol at 37% and 91%
• Plus linalool–eugenol, methyl cinnamate and bergamotene groups

The authors framed it positively: the availability of various chemotypes offers the opportunity to produce basil for specific market oils or for individual compounds such as (−)-linalool, eugenol, methyl chavicol, methyl cinnamate or methyl eugenol.

From the buyer's side it reads as a different sentence: the words "basil oil" do not specify which one you get. Methyl chavicol at 20% and at 72% share a plant name and a CAS number, and those two bottles differ by more than threefold in what you have to think about on safety.

Whole basil brings a brake; the essential oil does not

Methyl chavicol is estragole, and it is metabolised into a genotoxic and carcinogenic 1'-sulfoxy metabolite. Both of those metabolites have their own records in this database (1'-hydroxyestragole and estragole-2',3'-oxide), each with zero suppliers, pure research entries.

In 2013 van den Berg and colleagues at Wageningen asked something worth knowing (PMID 23959103). Working on basil-containing plant food supplements, they asked whether anything in the basil matrix inhibits the activation of estragole.

It does. Supplements made of powdered basil material contain compounds with considerable sulfotransferase (SULT)-inhibiting activity in vitro, whereas in supplements made of basil essential oil the presence of such compounds was limited. They identified the inhibitor as nevadensin.

They then used physiologically based kinetic (PBK) modelling to work out whether the effect occurs in vivo, and assessed risk with the Margin of Exposure approach. Their conclusion is more careful than the headline, so take it verbatim: the consequences of the matrix-derived combination effect would be significant if estragole were tested in rodent bioassays together with nevadensin at the ratios detected in supplements, raising MOE values. However, matrix-derived combination effects may be limited at lower dose levels, so the importance of such effects for the risk assessment of individual compounds should be judged case by case, considering dose-dependent effects.

For anyone blending, one sentence carries over: what you have is the essential oil, not the whole plant. Evolution put the inhibitor of the activation pathway and the precursor in the same leaf. Distillation separates them. It is the concrete version of are naturals gentler.

The GHS field says nothing about this

The oil's GHS classification is H227 combustible liquid, H302 harmful if swallowed, H315 skin irritation, H319 serious eye irritation, H335 respiratory irritation. Oral LD50 is 1,400 mg/kg in rat.

No mutagenicity, no carcinogenicity, no reproductive toxicity classification. That is not surprising in itself: mixtures are classified by their own rules, and a component whose content swings with chemotype is hard to hang on a generic "basil oil" entry. But the practical result is this: reading the GHS field alone, nothing sends you to look up methyl chavicol.

The regulatory field is equally quiet, reading FEMA GRAS, which is a flavour status. IFRA has separate provisions for estragole-containing materials, and the numbers get revised, so for anything going on skin, check the current standard directly. The lesson is the same one as in the 26 names on the label: an empty field is not safety, it is an empty field.

Buying and storing

110 suppliers, easy to source. One more question to ask before buying:

• Ask for the chemotype, not just the product name. CT Linalool, CT Methyl chavicol, CT Citral and CT Eugenol are four different things. If a supplier writes only "Sweet Basil Oil", ask for the GC report, or at minimum for the methyl chavicol range.
• Origin is a weak signal. In this database the Egyptian and Indian records are anisic and the Vietnamese one is licorice, which points the same way but guarantees nothing. The COA is the answer for your lot.
• You can smell it. The stronger the anise, tarragon and licorice direction, the more methyl chavicol. Not a quantitative method, but a useful first pass when a new lot arrives.
• Shelf life 24 months, cool, dark and sealed. Flash point 75 °C is lower than most essential oils, which matters for shipping classification.
• Specific gravity 0.890–0.930 and optical rotation −5 to −15 are two fields you can check yourself on arrival.

→ Sweet basil oil in the database: full physical data, 110 suppliers and suggested blends.

What this article does not establish

• "Odor family anisic means methyl chavicol dominant" is inferred from the odour descriptors, not from GC data on that record. The database has no percentage-composition field.
• I attribute the odor family differences across the twelve records to chemotype, but origin, plant part (herb versus leaf) and extraction method vary at the same time, and catalogue data cannot separate those variables.
• The Mississippi paper is an agronomic trial, not a survey of oils on the market. The distribution across 38 accessions is not the distribution of what you can buy.
• van den Berg and colleagues studied oral food supplements, not skin contact or inhalation. The "dose-dependent, case by case" caveat is the authors' own, not mine.
• I have quoted no IFRA or regional limit figures, because they get revised. Check the current standards.