Indolyl glucosinolates

BARTLET, E KIDDLE, G, MARTIN, A., WILLIAMS, I., WALLSGROVE, R.M., Induced increases in the indolyl glucosinolate content of oilseed rape and their effect on subsequent herbivoiy, Entomol. Exp. Appl., 1999, 91,163-167. 

Various alkyl isothiocyanates formed on enzymatic hydrolysis of non-indolyl glucosinolates of rapeseed were determined by GC-MS d70 Carbamoyl isothiocyanates (24) in solution exist in equilibrium with thiocarbamoyl cyanates (25). This equilibrium is well established at 80-90 °C. The species have distinct absorption bands in the IR region at 1980 and 2240 cm for 24 and 25, respectively ... 

Indolyl glucosinolates (+) Brassica napus, B.juncea and B. rapa (leaves) [122]... 

In contrast to aliphatic glucosinolates, indolyl glucosinolates such as glucobrassidan and its myrosinase-catalyzed transformation products have been shown to inhibit chemical and other types of cardnogensis induced by polycyclic aromatic hydrocarbons and other iiutiators (17). Indolyl glucosinolates are found abundantly in crudferae vegetables and are present in relativdy large amounts in the canola varieties of rapeseed. 

The concentration of glucosinolates in the meals of Triton and Hu You 9 was markedly reduced by the treatment of crushed seeds with methanol/ammonia/water. However, it is necessary to examine whether glucosinolates were extracted out of the seed, as such or were transformed to other products. Due to the complexity of glucosinolates in rapeseed and canola and lack of apparent concern over the fate of indolyl glucosinolates, only the four aliphatic glucosinolates were considered. 

Aromatic and heterocyclic isothiocyanates are unstable and easily hydrolyse to the corresponding alcohols. For example, 4-hydroxybenzyl isothiocyanate (the degradation product of sinal-bin, which occurs in the seeds of white mustard, Leucosinapis album, Brassicaceae) decomposes in normal table mustard to 4-hydroxybenzyl alcohol and thiocyanate ions (Figure 8.68). Isothiocyanates derived from indolyl glucosinolates behave similarly. 

Figure 2.3 Indolyl glucosinolates derived from tryptophan. These occur in most cruciferous vegetables, and degrade to a number of non-sulphur-containing degradation products, lndolyl-3-carbinol can conjugate with acetic acid to form ascorbigen.

S-Nucleophiles are very reactive in 1,3-addition reactions with nitrile oxides. A series of a-glucosinolates 27 (R = CR1=NOH R1 =Ph, CH2PI1, CH2CH2PI1, ( )-CH=CHPh, 3-indolylmethyl) was prepared by addition reactions of thiol 27 (R = H) with nitrile oxides (123). The indolyl-substituted glucosinolate was then converted to a-glucobrassicin 28. 

Indolyl-, alkyl- indolyl isothiocynates from glucosinolates via myrosinase (thioglucosidase)... 

Figure 2.2 Glucosinolate side chains (for details of R, see Figure 2.1), found within frequently consumed cruciferous vegetable and salad crops. Most crops contain a mixture of a small number of these, combined with glucosinolates with indolyl side chains (Figure 2.3).

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