Allium chemistry

Calvey, E.M., Matusik, J.E., White, K.D., DeOrazio, R., Sha, D. and Block, E. (1997) Allium chemistry supercritical fluid extraction and LC-APCI-MS of thiosulfinates and related compounds from homogenates of garlic, onion, and ramp. Identification in garlic and ramp and synthesis of 1-propanesulfinothioic acid S-allyl ester. J. Agric. Food Chem. 45(11) 4405-4413. 

Block, E. and Calvey, E.E., Facts and artifacts in allium chemistry, in Sulfur Compounds in Foods, Mussinan, C.J. and Keelan, M.E., Eds., American Chemical Society, Washington, D.C., 1994, p. 63. 

Block, E., Birringer, M., Jiang, W., Nakahodo, T., Thompson, H. J., et al. Allium chemistry synthesis, natural occurence, biological activity, and chemistry of Se-alk(en)ylselenocysteines and their y-glutamyl derivatives and oxidation products. J Agric Food Chem 2001, 49, 458 470. Das, A., Desai, D., Pittman, B., Amin, S., El-Bayoumy, K. Comparison of the chemopreventive efficacies of l,4-phenylenebis(methylene)selenocyanate and selenium-enriched yeast on 4-(methylnitrosamino)-l-(3-pyridyl)-l-butanone induced lung tumorigenesis in A/J mouse. Nutr Cancer 2003, 46, 179-185. 

Cai XJ, Block E, Uden PC, Sullivan JJ, and Quimby BD (1995) Allium chemistry identification of natural abundance organoselenium compounds in human breath after ingestion of garbc using gas chromatography with atomic emission detection. Journal of Agricultural and Food Chemistry 43 1751-1753. 

BLOCK AND CALVEY Facts and Artifacts in Allium Chemistry... 

One final example of artifact formation in Allium chemistry can be cited. Along with a variety of biologically active a-sulfinyl disulfides (RS(O)CHEtSSR ) isolated from onion (59,40) and termed cepaenes (59), a methanolic extract of onion contained 3-ethyl-6-methoxy-2,4,5-trithiaoctane 2-5-oxide (MeS(O)CHEtSSCH(OMe)-Et), which was assumed to arise from addition of methanol to die onion LF (8 )(40). 

Alliin-inosine 5 -monophosphate thermal interactions, 188-197 Allium chemistry allicin decomposition, 67-68 previous studies, 64-66 natural flavor identification, 63-64 product formation from chopped garlic, 65... 

Block E, Dane AJ, Thomas S, et al. Applications of direct analysis in real time mass spectrometry (DART-MS) in allium chemistry. 2-propenesulfenic and 2-propenesufinic acids, diallyl trisulfane S-oxide, and other reactive sulfur compounds fiom crushed garlic and other alliums. J Agric Food Chem. 2010 58 4617-25. 

Kubec R., Cody R.B., Dane A.J., Musah R.A., Schraml J., Vattekkatte A., Block E. Applications of direct analysis in real time-mass spectrometry (DART-MS) in Allium chemistry. (Z)-Butanethial S-oxide and 1 -butenyl thiosulfinates and their S-( ) -1 -butenylcysteine S-oxide precursor from Allium siculum. Journal of the Agricultural and Food Chemistry, 58 1121-1128 (2010). 

Furthermore, the aroma extract should be injected using the cold on-column technique. Unstable volatiles readily decompose in a heated injector block and form artefacts, e.g., hydroxyfuranones and thiols. Sulfur-containing compounds are particularly susceptible to heat-induced decomposition that can take place during split/splitless injection, GC separation, or in the GC-MS interface (61). Indeed, many newly reported constituents in Allium chemistry are artefacts (Fig. 13). HPLC and low-temperature GC and GC-MS conditions have been proposed for their analysis (62,63). 

Figure 13 Formation of artefacts in Allium chemistry. (A) AlUdn readily decomposes in a heated injector block forming two thioacrolein isomers before GC separation (62). (B) Bis-(l-propenyl)-disulflde rearranges at 85°C to thienyl compounds commonly found in Allium distillates (63).

E. Block, S. Naganathan, D. Putman, and S. H. Zhao, Allium chemistry HPLC analysis of thiosulfinates from onion, garlic, wild garlic (Ramsoms), leek, scallion, shallot, elephant (great-headed) garlic, chive, and Chinese chive, J. Agric. Food Chem. 40 2418 (1992). 

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