Glucosinolates

There is ample evidence from both animal experiments and tissue cultures studies to show that brassica vegetables and their constituents selectively induce Phase II enzymes. Evidence for the induction of Phase II enzymes by 

PEPTIDES, PROTEINS, AND OTHER AMINO ACID DERIVATIVES 

The Brassica family produces a wide range of glucosinolate compounds, anionic glycosides produced by the plant as antifeedant protective chemicals. As significant amounts of these compounds are left in the oilseed rape meals that remain after oil extraction, there is currently interest in exploiting these materials as crop-protection products for control of soil-borne diseases (Palmieri, 2003). 

The distribution of sinapine (2) (3,5-dimethoxy-4-hy-droxycinnamoylcholine) and aromatic choline esters in many genera of the Brassicaceae have been surveyed (Bouchereau et al., 1991). These compounds were analyzed by high-performance liquid chromatography (HPLC). 

Indole glucosinolates are especially sensitive many reports present erroneous data because these compounds are destroyed in isolation procedures (Slominski and Campbell, 

Isotopically labeled amino acids have been administered to excised plant parts. As is true for cyanogenic glycosides, incorporation of administered amino acid precursors into glucosinolates is often extremely high (up to 40%) (Larsen, 1981). In one study, plants were fed amino acids, and biosyn- 

Several of the putative intermediates contain a C-N double bond, presenting the possibility of geometrical isomers. The actual configuration of these intermediates has not been examined but is assumed to be the same as observed in the final glucosinolate (Poulton and Mpller, 1993). L-Cys-teine may serve as an efficient source of the sulfur atom in the thioglucoside moiety. 

S-Glucosylation of thiohydroximates catalyzed by UDP-G. thiohydroximate glucosyltransferases (EC 2.4.1.-) is thought to be the penultimate stage in glucosinolate biosynthesis (Poulton and Mpller, 1993). 

The cyanolipids, formally isoprenoid in their carbinol moieties, are of unknown biogenetic extraction. Assuming anabofic parallelism with the cyanogenic glycosides, then leucine, or, possibly, oxidized leucines, deserve attention as possible precursors.  

The established role of aldoximes as obligatory intermediates in the biosynthesis of cyanogenic glycosides is curiously duplicated in the in vivo synthesis of glucosinolates, another uniform group of constituents of higher plants discussed in the following section. 

Additions to group (I) ( Aliphatic Glucosinolates containing a C-Methyl 

Taken together, the recent findings have added confidence to the previously discussed protein amino-acid derivation of all natural glucosinolates. Moreover, the results suggest that future explorers within this area should hardly anticipate real structural caprices but rather be content with unexceptional modifications on biogenetically transparent frameworks. 

Biosynthesis.—Experimental work aimed at clarifying the biosynthesis of glucosinolates was initiated about 10 years ago. By 1968, when a detailed review 

POSOf represents a phosphoric-sulphuric anhydride which donates sulphate 

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Soybean meal is the most frequently used source of supplemental protein in the United States (5). Cottonseed meal is another important protein supplement. Both meals are by-products from oil extraction of the seeds. Canola meal is derived from rapeseed low in emcic acid [112-86-7] and glucosinolates. Linseed (derived from flax seed), peanut, sunflower, safflower, sesame, coconut, and palm kernel meals are other sources of supplemental protein that are by-products of oil extraction (4). 

Functional properties of canola protein products can be improved by succinylation (130,131). Controlled acetylation can reduce undesirable phenoHc constituents as well (132). However, antinutrients in canola and other vegetable protein products such as glucosinolates, phytic acid, and phenoHc compounds have severely limited food appHcations of these products. 

On treatment of trialkylsilyl nitronates 1043 with MeLi, LiBr, or BuLi in THF the resulting nitrile oxide intermediates 1044 afford, in dilute THF solution (R=Me) the ketoximes 1045 in ca 50-60% yield, whereas in concentrated THF solution the O-silylated hydroxamic acids 1046 are obtained as major products [144] (Scheme 7.35). Analogously, the silyl nitronate 1047 reacts with the 2,3,4,6-tetra-O-acetyl-/ -D-glucopyranosyl thiol/triethylamine mixture to afford, via the thiohydroxi-mate 1048, in high yield, a mixture of oximes 1049 which are intermediates in the synthesis of glucosinolate [145] (Scheme 7.35). 

Table 4.1 Glucosinolates in seeds of Cakile maritima and C. arabica (from Rodman, 1976)...

Unique among the collections reported in this study was the chemistry of subsp. euxima whose glucosinolate profile consisted essentially of a single compound, allyl glucosinolate. 

Louda, S. M. and Rodman, J. E. 1983a. Ecological patterns in the glucosinolate content of a native mustard, Cardamine cordifolia, in the Rocky Mountains. J. Chem. Ecol. 9 397-422. 

Differentiation and migration of Cakile (Cruciferae) seed glucosinolate evidence. 

FENWICK G R, KEANEY R K and MULLiN w J (1983) Glucosinolates and their breakdown products in food and food plants , Crit Rev Food Sci Nutr, 18, 123-201. 

GiAMOUSTARis A and MITHEN R (1995) The effect of modifying the glucosinolate content of leaves of oilseed rape (Brassica-napus ssp oleifera) on its interaction with specialist and generalist pests . Annals Appl Bio, 126, 347-63. 

SMITH T K, LUND E K and JOHNSON I T (1998) Inhibition of dimethylhydrazine-induced aberrant crypt foci an induction of apoptosis in rat colon following oral administration of the glucosinolate sinigrin , Carcinogenesis, 19, 267-73. 

The actual level of glucosinolates in the human diet depends upon many... 

Fig. 4.1 Sinigrin is an aliphatic glucosinolate that occurs at significant levels in the human diet, notably in mustard and Brussels sprouts. When brought into contact with myrosinase, derived either from plant cells or from colonic bacteria, it is broken down to yield a variety of products including the acrid, volatile, biologically active compoimd...

Table 4.1 Glucosinolates that have been studied in relation to their anti-carcinogenic characteristics and their common dietary sources...

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