5-Methylcysteine sulfoxide

Marks H S, Hilson J A, Leichtweis H C and Stoewsand G S (1992), S-Methylcysteine sulfoxide in Brassica vegetables and formation of methyl methanethiosulfinate from Brussels sprouts , J Agric Food Chem, 40, 2098-2101. 

S-Methylcysteine sulfoxide - precursor for 121 hemolytic factor dimethyl disulfide in cattle, but nontoxic to nonruminant animals... 

As in the case of propachlor mercapturic acid sulfoxide, the biological significance of xenobiotic mercapturic acids that contain oxidized sulfur is not known. Casida et al. (39) have reported that sulfoxidation of some thiocarbamate herbicides is a beneficial step in the detoxication process. However, cysteine conjugates can exhibit adverse biological activities. Smith (40) has reviewed work on the metabolism of the toxic principle in kale and has shown that C-S lyase action on S-methylcysteine sulfoxide produces the toxic principle. Virtanen ( ) has reviewed the processes in other plants that lead to the production of compounds with biological activity from -substituted cysteine sulfoxides. 

Garlic also contains S-propylcysteine-sulfoxide (PCSO) and S-methylcysteine-sulfoxide (MCSO). PCSO can generate over 50 compounds depending on temperature and water content. The action of allinase on the mixture of alliin, PCSO, and MCSO can produce many other molecules, including allyl methane thiosulfinate, methyl methanethiosulfinate, and other mixed or symmetrical thiosulfinates (R-S-S-R ), where R and R are methyl, propyl, and allyl groups. 

S-alkylcysteinase S-methylcysteine S-methylcysteine sulfoxide Methanethiol Methyl methane-thiosulfinate... 

S-Methylcysteine sulfoxide Allium cepa (Liliaceae) [bulb] HypoGlc, 4- cholesterol synthesis (AD rat)... 

The second pathway for the de novo synthesis of S-methylcysteine is by methylation of cysteine, as suggested by the more efficient incorporation in radish leaves of radioactivity intoJ-methylcysteine sulfoxide from [ C]cys-teine relative to that from [ C]serine, and from C]methionine rela-... 

Methylcysteine sulfoxide accumulates in certain plants of the Cruciferae and Liliaceae (Thompson, 1967), but could not be detected in several legumes or plants of six other families examined (Fujiwaraet ai, 1958). The compound has been isolated exclusively as (-t-XS-methyl-L-cysteine sulfoxide, suggesting that it is not formed as an artifact by chemical oxidation of 5-methylcysteine. 

Reduction of 5-methylcysteine sulfoxide to 5-methylcysteine has been demonstrated in the leaves of turnip and bean (Doney and Thompson, 1966). In turnip, the (-)diastereoisomer was reduced more rapidly than the (+)diastereoisomer, while in bean the opposite stereospecificity was observed. 

Griffith D.W., Macfarlane-Smith W.H., Boag B. The effect of cultivar, sample date and grazing on the concentration of S-methylcysteine sulfoxide in oilseed and forage rapes (Brassica napus). Journal ofthe Science of Food and Agriculture, 64 283-288 (1994). 

Like garlic, onion contains many organic sulfur compounds, including trans-S-(l-pTO-penyl) cysteine sulfoxide, 5-methylcysteine sulfoxide, 5-propylcysteine sulfoxide, and cy-... 

Some aspects of the catabolism of cystine in Brassica species have already been discussed in Section V,A. Mazelis et al. (1982) and Hamamoto and Ma-zelis (1986) reported cystine lyase preparations from turnip roots and broccoli buds which were active against cystine and S-alkylcysteine sulfoxides but were inactive toward cystathionine. Hall and Smith (1983) purified two isoenzymes of cystine lyase from cabbage leaves, the more active of which was inactive toward cystathionine. Both isoenzymes supported the production of pyruvate from 5-methylcysteine sulfoxide at rates faster than those obtained with L-cys-tine. However, the values for these substrates were considerably greater than... 

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