The Volatile Isothiocyanates in Fresh Cabbage¹

Abstract

The presence of four thioureas in a mixture derived from the volatile isothiocyanates of fresh white cabbage has been indicated by paper chromatography and countercurrent distribution. The predominant component has been proved unequivocally to be allylthiourea by isolation of S-methyl-S-allylisothiuronium picrate, and the presence of 3-methylthiopropylthiourea has been established unambiguously by chromatography and infrared spectroscopy. Evidence is presented that two of the remaining constituents are 3-butenylthiourea and 3-methylsulfinylpropylthiourea. Estimates of the quantities of isothiocyanates present in fresh cabbage are gi\ en.The nature of the isothiocyanates in various plants of the genus Brassica has been the subject of several recent investigations. 2 , 3 With few exceptions, the seeds, rather than the fresh parts of the plant, have been studied. The volatile isothiocyanates released from the thioglucosides in cabbage are believed to be of importance to the taste and odor of the fresh ~e g e t a b l e .~ The presence of allyl isothiocyanate in the head of white cabbage and of allyl isothiocyanate and 3-butenyl isothiocyanate in the head of red cabbage has been indicated, on the basis of paper chromatographic evidence in only one solvent system, by Kjaer and co-workers. 2a In the present investigation, the fresh, wet tissues of white cabbage heads were macerated, subjected to enzymatic action for the liberation of the mustard oils from the thioglucosides, and extracted with n-hexane. The resultant solution of isothiocyanates was steam distilled and converted to thioureas. Paper chro>natography indicated the presence of four thioureas, namely, allyl-, 3-methylthiopropyl-, 3-butenyl-and 3-methylsulfinylpropy1-thiourea5 The simultaneous occurrence of allyl and 3-methylthiopropyl isothiocyanates is reasonable since the former (or its glucoside) could be derived from the latter by the mere loss of methyl mercaptan.Allylthiourea was separated from the mixture by countercurrent distribution. I t was characterized by the formation of a crystalline derivative, S-methyl-N-allylisothiuronium picrate. The identity of the derivative with an authentic sample6 was established by a mixed melting point determination, X-ray diffraction analysis and infrared spectra of the natural and synthetic compounds, giving the first unequivocal proof of the occurrence of allyl isothiocyanate in fresh cabbage leaves.

Volatile Constituents throughout Brassica oleracea L. Var. acephala Germination

“…Volatile Composition. The chromatographic profile of kale materials (Table 1) revealed the presence of 66 volatile compounds, distributed in several chemical classes: alcohols (1, 2), carbonyl compounds (aldehydes (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14), esters (15)(16)(17)(18)(19)(20), and ketones (21-23)), norisoprenoids (24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35), terpenes (36)(37)(38)(39)(40)(41)(42), sulfur compounds (43-58), nitrogen compounds (59-64), and other volatiles (65 and 66). As far as we know, all of these compounds are described for the first time in kale.…”

Occurrence and Flavor Properties of Sinigrin Hydrolysis Products in Fresh Cabbage

“…1), is well known for its contribution of both pungency and lachrymatory properties to black mustard and horseradish (Clark, 1992). Allyl isothiocyanate also has been found in freshly disrupted cabbage tissues (Clapp et al, 1959;Bailey et al, 1961;Chin and Lindsay, 1993), and has been considered an important contributor to fresh cabbage flavors (Hasselstrom, 1957;Schwimmer, 1963;Chin and Lindsay, 1993).…”

Chemical Variability and Biological Activities of Brassica rapa var. rapifera Parts Essential Oils Depending on Geographic Variation and Extraction Technique

“…However the all identified components in B. rapa var. rapifera parts essential oils were already identified before in Brassica genus …”