Glucoside indoxyl

Important indole derivatives (see Scheme 2) include (i) indigo, a vat dye known and widely used since antiquity, and originally obtained from indican, a (3-glucoside of indoxyl which occurs in some plants. Indigo is now prepared synthetically. Tyrian purple, a natural dye used since classical times, is 6,6 -dibromoindigo (ii) the numerous indole alkaloids, with complex derivatives such as yohimbine and strychnine (iii) tryptophan, an essential amino acid found in most proteins. Its metabolites include skatole and tryptamine and (iv) 3-indoleacetic acid, which is important as a plant growth hormone. 

Indigo (178a) was originally prepared from an indoxyl glucoside occurring in various species of Indigofera (Leguminosae), until the industrial synthesis was developed. 

Indican a glucoside composed of indoxyl and one molecule of ucose, m.p. 57 "C, [a]n -66° (water). It occurs in Indigofera species, e.g. the indigo plant (Indigofera tinctoria), and several other higher plants. It is the precursor of natural Indigo (see). 

Indoxyl derivatives LC, detection limits using FIA Indoxyl sulfate 2.3 pmol, indoxyl phosphate 3.1 pmol, indoxyl acetate 1.7 pmol, indoxyl 1,3-diacetate 0.4 pmol, indoxyl ) -D-glucoside 0.0015 pmol, indoxyl ) -D-galactoside 0.0015 pmol, indoxyl ) -D-glucuronide 0.0023 pmol, tryptophan 0.25 pmol (201)... 

In addition to the anthocyanins, another important source of dyes is the naturally occurring indican which on hydrolysis yields indoxyl and glucose. The indoxyl upon oxidation is converted to the dye indigo. The preparation of indigo from plants involves the extraction of the glucoside, its enzymic hydrolysis by microorganisms, and the oxidation of the indoxyl to indigo by air. The synthesis by Robertson (Iof indican, illustrated below, fur-... 

IndIcan org chem C14H17O6N A glucoside of indoxyl occurring in the indigo plant on hydrolysis indican gives rise to indoxyl, which is oxidized to indigo by air. In-da,kan )... 

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