Talk:Lawsone

Henna is present in impatiens balsamica, not walnut. Juglone is present in walnut. 1hennaphd 06:08, 7 February 2007 (UTC)

Usually in plants that produce large amounts of anthraquinones or naphthoquinones, you will get a wide variety of isomers, like both juglone and lawsone (remember, the two differ only in that the placement of the OH group is on the aromatic ring in juglone.) The article cited from the International journal of cosmetics lists walnuts as a source of lawsone, please see that for more information.

In fact, if you did a profile of all the compounds in either henna, walnuts, or jewelweed, you would probably find a huge amount of overlap in the compounds produced. It is often pointed out that humans and apes have >99% similarity in their genomes, and many plants share large amounts of genes with each other as well. It would come as no surprise if henna, walnuts, and jewelweed shared a similar or identical set of genes for producing this varied quinones.Jeff Dahl 21:06, 7 August 2007 (UTC)

there are more inconsistencies in this article. I would love to have explained in detail how lawsone bound via the micheal reaction to keratin.

Basically what happens is that nucleophiles (abundant on proteins and many other biological molecules) will "attack" one of the beta carbons on lawsone (both of these are alpha to one carbonyl group and beta to the other carbonyl group, so either could be attacked, however steric hinderance of the top one should mean the lower one is preferred). Then, the electrons are "pushed" (hard to only describe with words, see michael addition article for electron pushing) so that the top carbonyl becomes an OH group and the double bond is moved up. Again, see the michael addition article for details, specifically structure 3 will show the red arrows.

also the "can" in the sentence: "In an acidic solution, lawsone can react via michael addition with the protein keratin in skin and hair, resulting in a strong permanent stain that lasts until the skin or hair is shed." is for me not very clear. Means that, that lawsone can bound to keratine with another reaction?

The reaction is called the michael reaction. The two things that are reacting together are lawsone and the protein (for example, keratin). This reaction will be able to happen in an acidic solution. If you are asking whether lawsone can bind to keratin by a different reaction, perhaps at a different pH, I have no idea.

I am a German and found in the German wikipedia in the rubrik weblinks in the entry henna one link to the Botanist Dr. Imhof of the University of Marburg [1] who he explains in the "[Beschreibung der Art]"= description of the species [2] development of the dye Lowsone in the following way (this is the verbally translation):

Lawsonia inermis L. (Henna)

Its flowers are supposed to give off one of the strongest fragrances in the plant kingdom (this is also said of Pandanus tectorius). Dried and ground, the leaves and stem form a grey-green powder that is then traded. The colorant is Lawson (1%, with 5-10% tannins), although it is only created through enzymatic hydrolysis of glycosides (hennosid) and subsequent oxydation of the aglycon. The ancient Egyptians already used it as body decoration for skin, nails and hair. In India, painting the palm of one's hands is still very popular. Henna also seems to experience an upswing at the moment as a colorant for nonpermanent tattoos. On wool, without mordant this oxydation dye produces an orange-brown colour. To dye hair, the powder was mixed with lime and water (often also animal urine, which favours the enzymatic reaction, see isatis and indigofera) and applied to the hair still warm. In damp heat (equally favourable for the hydrolysis), e.g. in oriental steam baths, or in temperate climates wrapped in cloth, this dyed hair permanently. Depending on the recipe (sometimes powdered indigo leaves are mixed in to modify the colour), natural hair colour and previous treatment of the hair, the resulting colour varies between carrot and mahogany. Black hair cannot be dyed this way. The roots are also capable of colouring.

The word "created" is a little subjective here. Lawsone exists in the plant already and is severed from a sugar during hydrolysis. It should also be mentioned that enzymatic hydrolysis is not the only way for this to happen. It can also be done by acid hydrolysis. Its just a slower process. DaisyDarling (talk) 12:34, 10 July 2008 (UTC)

I note that the chemistry of 1,3 diones as in lawsone give rise to a very acidic methylene carbon between the oxo moieties. The enolate is significantly stabilized by tautomerism between the enolate and carbanion forms. In lawsone, the neighboring carbonyl is significantly electron withdrawing and helps to stabilize the conjugate base form. But, surprisingly, alkalized henna reacts sluggishly when placed on hair, but mildly acidified henna reacts quickly, as though the lawsone were principally acting as an electrophile - even though that's sterically limited. Ideas?

Steve (talk) 13:53, 14 December 2016 (UTC)

what I really want to know is this, if the michael-addition is or can be an oxydation, and is it for example possible to perform an oxidation via michael-addition or is the michael-addition contradictory to oxidation? In the Encyclopædia Britannica "addition reaction."from Encyclopædia Britannica 2007 Ultimate Reference Suite . (2007). the michael-addition is defined as: "any of a class of chemical reactions in which an atom or group of atoms is added to a molecule"

--Olga Engelhardt 13:40, 22 April 2007 (UTC)

Don't think of the michael addition in terms of oxidation, I think the oxidation the author was talking about is this: many compounds present in plants exist coupled to different sugers (the compound is then referred to as glycosylated) to release the compound you want (the aglycon, meaning without sugar) you can sometimes cook it or expose it to acid, or as the author states, let it undergo enzymatic hydrolysis. After this, other treatment may be necessary, as the author is suggesting further oxidation. Quinones, anthraquinones, or naphaquinones like lawsone are themselves oxidized molecules of, for example, catechols or other phenol-type or poly-phenol compounds. I hope this answers your question. Jeff Dahl 21:06, 7 August 2007 (UTC)

Lawsone turns darker on hair/skin over time (changes color from bright orange to reddish brown within a couple of days). What is the chemistry behind this process? Is the color change a side effect of the binding of the lawsone to keratin, or is it an independent process? (The darkening is commonly referred to as oxidation, in which case it would be independent from the binding process as described here - is it?)

Irisalsusername 23:34, 13 August 2007 (UTC)iris