Raw Materials Indole: The Maestro Is Decomposing

Indole: The Maestro Is Decomposing

05/19/16 16:03:41 (21 comments)

by: Matvey Yudov

You might have noticed the word Indole in discussions about jasmine, lilies and other white flowers, with either good or bad connotation. Sometimes it is even used as a euphemism for an unpleasant odor. But not many of you have come across pure indole in real life. It comes in a form of a gray powder. Let's find out what indolе is.

In the book The Perfect Scent: A Year Inside the Perfume Industry in Paris & New York, Chandler Burr re-tells Jean-Claude Ellena's joke about Calvin Klein Eternity, one of the most indolic perfumes ever created. Ellena tartly pointed that indolе smells like corpse and that it was very feminine to smell like death applying it from a flacon ironically named Eternity.

In the beginning of the 90s I got a sample of Eternity, it always made me feel tranquil and balanced, but I tried not to overindulge myself with this effect. Once, before an exam, I applied a bit of it on my skin. I felt pretty confident, but it was the only time I was kicked out the door. The professor completed his verdict with the phrase: "Along with your smell you leave a very disastrous impression."

Indole or benzopyrrole is a simple nitrogen-containing organic compound. Indole and its derivatives play an important role in a great number of life processes. Life, as you know, is a form of protein existence. In its turn, proteins are chains of amino acids. L-tryptophan is one of those important amino acids, it is an essential part of proteins in all living organisms. L-tryptophan is an indole derivative [you can see a fragment of indolе in all formulas in the picture below].

Apparently, Indolе itself (and its closest analogue Skatole) forms during the process of tryptophan decomposition by putrefactive bacteria (during the decaying of organic matter or in the intestines). The scent of indole in pure form is described as extremely unpleasant (once I came across a poetic metaphor on its account: "a smell of rotten cabbage's inner stalk"). But the meaning of pleasant and unpleasant is so very subjective.

Pure indole possesses a very complex aroma, in big concentrations it really has a strong fecal character, but this is not all, what is even more prominent here is Naphthalene (a familiar smell of traditional mothballs); combined together they produce an 'indolic' earthy musty animalic smell. When strongly diluted, to 0.1% or less, another one of its characteristics comes into the spotlight, a floral note reminiscent of jasmine. The scent of Skatole is more intense and fecal. Strictly speaking, skatole forms what we call a fecal smell.

Indole is an integral part of the odor of certain flowers. You smell it in jasmine absolute [for the first time it was isolated from jasmine absolute and described as a key ingredient in its odor profile more than a hundred years ago]. In absolute of narcissus and champaca its content might reach several percent! We call such floral scents narcotic or intoxicating. Traces of indole can be found in ylang essential oil, as well as in neroli and some citrus oils, for example, bergamot and petitgrain.

Most probably, a big quantity of indole in the smell of some flowers was developed during evolution in order to attract a bigger population of pollinators. You know that some plants cooperate exclusively with flies engaging them with a strong stench of rot and feces.

The nucleus of indole is a part of a big number of physiologically active compounds. Let's take a look at the structure of serotonin, also known as a 'happy hormone', which is certainly a silly legend for those who seek simple answers to difficult questions. You can also find it in the melatonin formula, a hypophysis hormone which regulates our sleep at night and which you might know as a medication to help during jetlag. There is a big group of alkaloids, indole derivatives, in the picture above, please take a look, and we will proceed dealing with indole exclusively as a smell, leaving all its other roles aside.

Gardeners know about the important plant hormone Heteroauxin, or Indole-3-acetic acid, that naturally occurs in plants but can also be chemically synthesized and used as a growth stimulator. The smell of heteroauxin, which is indole derivative, is very close to that of indole.

Perfumers do not use indole exclusively in jasmine accords, very often it is added to different floral and abstract compositions; the right proportion of indole, as well as other animalic ingredients such as Civet, for example, provides a comforting warmth and depth to perfume as well as additional animalic sensuality. Animalic effects are very expressive, but this is also the reason to deal with them cautiously and gently.

Indole is not always a good solution for a perfect annimalic or floral addition. Its weak side is the mothballs effect, mentioned above. This one is not welcomed in many compositions, especially when it already contains heavy terpenes as a part of many natural essential oils which smell of turpentine generally. Together they smell bad.

Another flaw is in indole interaction with aldehydes, they form a Schiff base. Although it doesn't much reflect on the scent itself, this organic compound causes darkening of the perfume liquid with time, which is not always pretty. The answer is replacing indole with other ingredients, and Indolene is one of the most popular among them. Indolene is a product of the interaction of Hydroxycitronellal with Indole which is more floral and soft. Another favorite alternative is Indocolore, a non-nitrogen-containing compound, which possesses a more intense indolic character, but does not have this annoying mothballs or naphthalene effect.

Top image by Larson
 

Mat Yudov

Mat Yudov is a chemist, perfumer, and musician. Mat is a researcher and specialist in the chemistry of aromatic materials. He graduated from Moscow State University "Lomonosov" in 1999. He writes for the popular perfume blog leopoldray.blogspot.com (in Russian).

 



Previous Raw Materials Next


Advertisement

mindcaviar
mindcaviar

I have learned so much. Thank you for this article.

Oct
01
2016
kschrotel
kschrotel

Thank you, Matt. I have read much about Indole, but never have I had all the elements of the good points and not so good areas described so succinctly, so understandably well. Now, if I could only beguile a night-blooming jasmine plant to grow and release one single blossom of scent, here in the soggy bottom of a very rainy Ohio... I would be a happy woman!

May
22
2016
Marilimorajaspani
Marilimorajaspani

Fascinating article. I have twice had the fecal experience when layering different perfumes. Nuda of Nasomatto is a beautiful Jasmine but when I layer her with another perfume, I sometimes get terrible results. One time I walked out of my bathroom and I thought the dog had made a mess somewhere, I checked my shoes, I looked under the bed and then I realised that it was my perfumes. I have since found 2 combinations that produce this effect, on one occasion the stench was so clear and strong that I had to get back into the shower.
Thanks again for the fascinating read.

May
22
2016
HeidiLynn
HeidiLynn

Thank you this was very informative. Indoles are not an automatic
No for me, but I know they can make or break a fragrance. I appreciate this insight!

May
21
2016
Militza
Militza

I really enjoyed your review. While I do not have the chemistry background that my son has, I followed enough, and I am glad to know why I must side with the professor. I would not be quite as candid, but once my brother bought my mother Eternity and I finally had to ask if she would not wear it when I was around. I never could like it very much, and I did not know why. Many scents from Calvin Klein are awesome, but this one was not for me. It is nice to know why. For those who like it and wear it well, that is fine. There is this point where it hangs on one's nose in an odd way for some of us, however.

May
21
2016
Playtime
Playtime

What a wonderful read! Thank you. Didn't know that there was such a variation in indoles.

May
21
2016
zoka
zoka

Mat another awesome article! Just keep them coming.

I remember when we were creating Swan Princess for The Vagabond Prince how insightful was the experience in the lab with Bertrand Duchaufour. He was demonstrating us several times how indole perfumes have it's own rules and one of them is how aldehydes strangely interact with them.

I really like this scientific insight to perfumery that is very nicely packed in Mat's articles like gummy-bear vitamins for kids.

May
20
2016
Gearoid
Gearoid

Interesting article. I'm becoming more and more a fan of indolic white flowers.

May
20
2016
hellovascent
hellovascent

And another great one from Mat! Thank you very much for this as well as the Gary Larson cartoon.

May
20
2016
bibibling
bibibling

Thank you!! Love these kinds of articles!

May
20
2016
ArkangeL
ArkangeL

*****

May
20
2016
polly golightly
polly golightly

as a chemist I really enjoyed this contribute! <3

May
20
2016
EmiliM
EmiliM

Great article, thank you!

May
20
2016
scarlett.angel
scarlett.angel

Love indolic flowers too. I never thought of CK Eternity as indolic though; it smells fresh, spicy and refreshing to me! Not a fragrance that's a favourite; but now I understand why I'm drawn to it anyway. DMT: The Spirit Molecule is a great documentary btw.

May
19
2016
FrkFors
FrkFors

Oh I LOVE jasmine, tuberose, champaca, narcissus and all of those types of flowers! Thanks for the interesting read and documentary!

May
19
2016
mikemuscles21
mikemuscles21

I am finding all the articles today so fascinating, and definitely this one. What a fascinating read.

May
19
2016
ellina1984
ellina1984

Τhis was so very interesting, thank you for taking the time to put together all this information and present it so clearly.

May
19
2016
lemonzest
lemonzest

Indolic notes such as those in jasmine and tuberose perfumes are some of my favorites. I did not know Eternity was redolent of these notes because I thought only sharp white florals were indolic. Guess not! Eternity presents more carnation and spicy green notes to me - I need to smell it again.
On a creepier note, this may explain why I always seem to wear Eternity to funerals. Seriously - not making a tasteless joke, I always crave Eternity for wakes, funerals, and such. To me it seems light and inoffensive, but so are other scents I own. But I specifically and deliberately wear it to bereavement events. Huh. I definitely need to smell it again.

May
19
2016
NebraskaLovesScent
NebraskaLovesScent

I didn't care for jasmine scents until I smelled real jasmine grandiflorum absolute. It is indeed a narcotic aroma. Now I love jasmine-y perfumes that keep at least a little of that indole scent intact. Very interesting article, Mat! Thank you!

May
19
2016
juji
juji

Very interesting! Thank you!

May
19
2016
kvan
kvan

Brilliant! Thank you for this article, Matthew, and Fragrantica. I'd love to see more articles of this kind.

May
19
2016

Add Your Review

Become a member of this online perfume community and you will be able to add your own reviews.

Advertisement

Advertisement

New Perfumes

Bonbon Spring SummerViktor&Rolf
Bonbon Spring Summer

Sun Pop Green FusionJil Sander
Sun Pop Green Fusion

Sun Pop Coral PopJil Sander
Sun Pop Coral Pop

Sun Pop Arty Pink Jil Sander
Sun Pop Arty Pink

Sunkissed DreamsHawaiian Tropic
Sunkissed Dreams

Island ResortHawaiian Tropic
Island Resort

Summer DreamsHawaiian Tropic
Summer Dreams

Golden ParadiseHawaiian Tropic
Golden Paradise

Evening Rose D`OrAerin Lauder
Evening Rose D`Or

Tangier Vanille D`OrAerin Lauder
Tangier Vanille D`Or

1881 SignatureCerruti
1881 Signature

Pure Grace Summer SurfPhilosophy
Pure Grace Summer Surf

First Instinct for HerAbercrombie & Fitch
First Instinct for Her

Leather SensationByblos
Leather Sensation

Metal SensationByblos
Metal Sensation

Solarissimo MarettimoAzzaro
Solarissimo Marettimo

Musk MalakiChopard
Musk Malaki

Bonjour SeñoritaTous
Bonjour Señorita

Mia Me MineHalloween
Mia Me Mine

Gisada UomoGisada
Gisada Uomo

Gisada DonnaGisada
Gisada Donna

KastellorizoMaison de Parfum Berry
Kastellorizo

AdoualaMaison de Parfum Berry
Adouala

Ambre 35Maison de Parfum Berry
Ambre 35

Coeur NoirMaison de Parfum Berry
Coeur Noir

Violette RebelleMaison de Parfum Berry
Violette Rebelle

PortraitMaison de Parfum Berry
Portrait

CathédraleMaison de Parfum Berry
Cathédrale

Éblouissants RefletsMaison de Parfum Berry
Éblouissants Reflets

MystiqueMaison de Parfum Berry
Mystique

Popular brands and perfumes: