Glucosinolates from Amino-acids, with Preservation of Nitrogen

In this context the recently documented, specific incorporation of l-nitro-2-phenylethane (85) into benzylglucosinolate in T. majus, comparable with that of DL-phenylalanine, deserves attention. Definite proof that the nitro-com-pound, or maybe rather its aci-tautomer (86), plays the role as a true intermediate, foreshadowed several years ago, is still outstanding and will supposedly require studies at the enzymic level. If confirmed, the subsequent steps, (86) - (87) - (88), appear unexceptional and not without in vitro analogies. What remains a fact is that phenylacetaldoxime in the intact plant gives rise to the production of l-nitro-2-phenylethane, present in shoots of T. majus, albeit in concentrations as low as SO pg per 100 g of fresh weight.  

The terminal step, O-sulphonation of desulphobenzylglucosinolate (90), is catalysed by a sulphotransferase, isolated from T. majus, utilizing 3 -phospho-adenosine S -phosphosulphate (PAPI as the sulphate donor and possessing very little specificity for the type of desulphoglucosinolate used as the substrate. IWs finding calls for caution, in addition to that previously ex- 

The extent of community is further apparent from the observed incorporation in horseradish leaves of 4-methylthiobutyrothiohydroximic acid (103), desulpho-3-methylthiopropylglucosinolate (104), and the corresponding sul-phonated product (105) into allylglucosinolate (106) to the extent of 50-73%, 

Matsuo and M. Yamazaki, Chem. and Pharm. BuU. (Japan), 1968,16,1034. M. Matsuo, Tetrahedron Letters, 1968,4101. 

Since this field was previously reviewed, a vastly more detailed picture has emerged of the beautiful and simple relationship between amino-acids, cyanogenic glycosides, glucosinolates, and, perhaps less apparent, other constituents of higher plants. It is a task for the future to fill in still more details, so that we may ultimately comprehend the full biological significance and consequences of this relationship. 

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