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Azulene and Chamomile

Éva Marie Lind, LiAM
LiAM - Licentiate in Aromatic Medicine ( France UK )

One of the finest examples of the transformation of how an essence changes its color through the processes of distillation, as well as extraction, would be a short introduction and a brief discussion to the Chamomiles and the primary component, azulene.

“The term “azulene” was introduced by Piesse, who suggested the name for the blue-colored constituent of Chamomile Oil” and related plants, in the 1800’s. * It is interesting that the name was chosen for color, rather than aroma. [Also Piesse is credited with classifying fragrance to musical notes. Piesse discovered that perfumes were altered and transformed from their initial aroma profiles when they were applied to the skin.] In similar manner, through distillation, molecules can also be combined, or even, in the case of azulene, created, to also alter an essential oil’s fragrance.

Azulenes are the compound group of which the constituent chamazulene, from chamomile (cham for the plant, azulene the compound group) resides. It is most frequently found within the essential oil bearing plants of the Asteraceae family and is directly responsible for the beautiful variables of blue we see within these oils and extracts. These include Artemisia arborescens (dihydrochamazulene) and A. douglasiana, Tanacetum annuum, Achillea millefolium, Chamaemelum nobile and Matricaria, as well as the Elecampane (Inula helenium).

Azulenes also reside in an assembly of oils beyond this grouping of oils distinguished by the name "blue oils". These include many other plants as well, Elemi (elemazulene), Eucalyptus (eucazulene) and even Vetivert (vetivazulene). The quantity of azulene in the essential oil will determine the percentage of color intensity within the oil; some plants produce a plentiful composition of azulene, such as chamomile, that has brilliant color, while others do not.

Azulenes, although linked to the color hues of blue, can also be green, violet, blue/violet and red/violet. The brilliancy of this rainbow is thought to be a result of the parent skeleton’s, a 5-member ring with 2 double bonds and a 7-member ring with 3 double bonds and a superb ability to absorb light. As a whole, azulenes reside in the chemical classification group of bicyclic unsaturated hydrocarbons, sesquiterpene derivatives, with C₁₅H₁₈ as their empirical formula.

In addition, some essential oils will have more than one azulene within its chemistry profile, in which case the first will be labeled after it's botanical and the second after it's color. I.e.: Vetivert contains both vetivazulene (veti for genus) and verdazulene (verd for green). In addition, some oils may share the same azulene, such as with yarrow, which is comprised of chamazulene, again, named such because it was first discovered in chamomile.

Azulenes are generally considered latent components, "present but not evident or active" (Webster’s definition), within a number of aromatic and herbal plants. Some azulenes occur naturally, within the plant, or the oil, while others, such as chamazulene classically a component of German chamomile, are created from a precursor within the steam distillation process. The synergy of heat and pressure required for the distillation of this plant, (constituents are what would be termed "high boiling, requiring extreme and lengthy charge) and the inherent precursor within Matricaria of matricin, combine to produce the azulene based constituent of chamazulene. Once distilled over, it will both alter the color and odor profile of the resultant oil and the longer the oil is distilled, the brighter the blue the hue and the more diffusive the aroma.

The amount of azulene within an essential oil, the percentile, will oftentimes determine color composition. Some oils have quite a bit of azulene, such as Chamomile and this profoundly alters its color. In other essential oils, the azulene content is fractional and does not affect the oil’s color scheme. It is interesting to note, that with Roman chamomile, Chamaemelum nobile, the color profile preferred in the aromatic industry, is that of pale golden amber. However, it has been shown, that if distillation time is extended on this plant, its color hue will also begin to change, as residues of azulene blend to the mix. In France , where the golden-hued oil is considered the ideal color profile for Chamomile, the oil will be distilled with methods that prevent the formation of azulene. It is also in this country where I first learned of the tremendous respect this oil is given for its internal as well as external properties, as an antispasmodic, anti-inflammatory and to relieve gastro-intestinal associations of distress.

In addition, the time of day when your azulene rich plants are distilled will affect the resultant azulene proportions. In general these plants are distilled in the morning or evening, and with the plants needing an extended charge, a long distillation, of between 7-13 hours is needed. Distillation generally begins in the morning or evening, due to preferred climatic harvest and "cooking" temperature hours and oftentimes, as in the case of Blue Chamomile (Matricaria recutita), will require additional cohobation, (the re-distillation of the waters). Maintaining these guidelines, not only ensures a nice proportion of chamazulene, but as well, the azulene derivative of bisabolol, which in combination, affords chamomile its wonderful reputation as an anti-inflammatory. Also it is important to note that the age, the plant’s origin and the storage conditions, will often affect the percentage range of azulene a distiller can expect to recover, or "pull over" in their oil.

Of an interesting perfumery note, Arctander relays an experience where the method of extraction, not distillation, used to acquire the absolute of chamomile, could actually capture an "extraordinarily high" level of azulene. Not much relationship to the uses for clinical therapy, as extracted oils are generally not applicable, however, for fragrance and natural perfumery, which chamomile absolute is sought after for, it is indeed a viable factor. He continues with the notary remark that it is the content of azulene in combination with other hydrocarbons contained in chamomile that can influence a "rubber-like" note, the fragrance influencing associated to this compound group. It is also interesting to note, as we move to the time when we are desiring less man-made tampering of natural perfumery elements, that the absolute of chamomile is being met with more adulteration, with the entry of the modern synthesized version of chamazulene.

The beauty of oils rich in azulene components at large enough percentages to influence their color profile, as the blue oils, is that you can easily determine when an oil has reached it's prime, has oxidized (subjected to air and light), through it's color changes. Your more yellow oils will turn muddy with tinged with brown and your blue oils will meld into a black green - like dirty moss. For this reason, when you receive your essences rich in azulene, it is terribly important to use a professional/perfume blotting stick (pbs) to test the oils as soon as they arrive - and return if it is not fresh. Dark bottles are going to obscure this until you do. You must also keep your bottles tightly capped, cool and stored in an area with reduced light. This is essential to keep your oils fresh. One of the prime challenges with oils rich in azulene, is keeping it "fresh", but the beauty, is that in its "look and "temperament" it lets you know not only aromatically, but visibly, when it has gone off.

SOURCES OF REFERENCE:
1. Addison, Carole, Kurt Schnaubelt, Perl Stedman, PIA, Sources For Purity, THE SOURCE BOOK OF ESSENTIAL OILS FOR AROMATHERAPY, ©1997

Discusses the introduction of the term azulene in Volume II, Page127, referring to Compt.rend. 57 (1863). Chem News 8 (1863), 245, 273.

Authors Bio: Éva-Marie Lind-Shiveley has specialized in holistic aromatherapy for 15 years. She has practiced as a clinical aromatologist and held the position of program lead and department dean at private career colleges in natural health. She has also worked in research, marketing and design for aromatherapy product-based companies. A resident of Portland , Ore. , she now lectures and writes on the uses of medicinal and aromatic plants and can be reached at emlessence@prodigy.net. Her current book Aromatiques, A Sensualist’s Guide to Aromatic oils, is published by Bay Books of California in 2002.

be used without the prior permission of Eva-Marie Lind.