Hello, I am trying to understand the chemistry involved in indigo extraction from plants.
In the undamaged plant tissue, the indigo precursor is indoxyl glucoside (indican).
There is a paper by Minami et al. Biosci. Biotech. Biochem. 60, 147, 1996 that describes a beta-glucosidase from Japanese indigo (Persicaria tinctoria) with high specificity for indican, hydrolysing it to form indoxyl. And all sources agree that indoxyl dimerizes in oxygenated conditions, forming indigo.
But many of the extraction methods described use conditions that will inactivate the beta-glucosidase such as high temperature. Yet, people still report good indigo yields.
So my question is this: is an active beta-glucosidase required during extraction of natural indigo from plant tissue, or are there conditions where indican will be hydrolysed non-enzymatically?
Indican ( indoxyl- b- D - glucosside ) is a precursor of blue dye indigo and is present in large amounts in Polygonum tinctorion L. leaves. When leaves are broken the indican is hydrolyzed to indoxyl and glucose, the indioxyl yielding indigo. by native B-glucosidase to indoxyl . The more recent findings is that at temperature 100C the ability to promote indigo formation was higher in P. tinctorium than that of native B- glucosidase and as such is considered as a new industrial for naatural indigo production For more information consult https://core.ac.uk
Is an active beta-glucosidase required during extraction of natural indigo from plant tissue, or are there conditions where indican will be hydrolysed non-enzymatically?
From the indican chemical structure it seems more stable for the non-enzymatic hydrolysis. So, probably, beta-glucosidase plays main role in this process.
Chapter Natural dyes: their past, present, future and sustainability
The chemical structure of the indoyl glycoside at position 3 of indole ring, can be hydrolysis beta glycosidase to liberate both two inactive ingredients, ity.ndole 3- ol and glucose moiety
Thank you all for your replies.
Yes, Faris Abachi , from the literature, there is no doubt that beta-glucosidase hydrolyses indican. But can it be hydrolysed non-enzymatically?
Sylvester Peter Antai , the kind of process you mention is exactly what I am not able to understand! At 100C, the enzyme should be completely inactive, probably denatured. So why does the process work? Is the enzyme not needed, or is it actually active, at least for enough time to catalyze sufficiently? Would you be able to provide a reference or a direct link?? The link you gave just went to the front page of core.
Nodirali S. Normakhamatov , would you be able to say what it is about the structure that makes you say it would be stable to for example acid or base hydrolysis, or high temperature?
I mean more stability of the glycosidic linkage in the indican for its hydrolysis in low acidic and base medium than the enzymatic cleavage.
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