Allium species

Kubec R, Svobodova M and Velisek J (2000), Distribution of 5-alk(en)ylcysteine sulfoxides in some Allium species. Identification of a new flavour precursor S-ethylcysteine sulfoxide (ethiin) , JAgric Food Chem, 48, 428-433. 

Nencini C, Cavallo F, Capasso A, Franchi GG, Giorgio G and Micheli L. 2007. Evaluation of antioxidative properties of Allium species growing wild in Italy. Phytother Res 21(9) 874—878. 

Fungal disease that survives on crop debris and wild Allium species. May be worse on nitrogen-rich soil or where potassium levels are low. 

Figure 2. Organosulfur compounds from allium species...

If the disulfides are methylpropenyl disulfide or propylpropenyl disulfide (Scheme 7.3a) this may lead to thiophene compounds [31,32]. This is not a very common process in freshly cut Allium species, but heating seems to promote this process [33, 34]. 

Scheme 7.3 Enzymatic production of sulfur-containing flavour compounds in Allium species from amino acid flavour precursors, a S-Alk(en)yl cysteine sulfoxides and b (+)-S-l-propenyl cysteine sulfoxide (isoalliin) P-5 -Ppyridoxal-5 -phosphate...

Table 7.5 Key flavour compounds in Allium species (Alliaceae)... 

The vegetable radish (Raphanus sativus L.) shows mild pungency attributed to 4-methylthio-3-butenyl isothiocyanate. Other vegetables of the Brassica and Allium species, too, are reported to contain small amounts of these isothiocyanates, but they are possibly diluted and altered during cooking, and so have not been reported as exhibiting sensory pungency in foods. 

Cycloaddition reactions of thioaldehydes and sulfines are most probably encountered in plants, as elegantly and soundly shown by the group of Eric Block during their investigation of sulfur products occurring in the Allium species (for a review see [91]). They were able [92, 93] to isolate bicyclic dithioacetal oxides, called zwiebelanes, and also to synthesise them from a thioxosulfine, already described in this review (Sect. 2.6, Scheme 18). An extremely rich stereochemical and analytical study has resulted. 

A large number of organic sulfur compounds have been detected in extracts or distillates prepared from garlic, onions, or other Allium species. This chemistry has been reviewed by Block. Polysulfanes have been detected in many of these preparations but most recent results show that fresh extracts of garlic, prepared under mild conditions (20 °C), did not show any polysulfanes R-S -R n > 2) when analyzed by RP-HPLC analysis. ... 

When garlic is extracted by methanol, aUyl methyl trisulfane is formed. Unsaturated polysulfanes from Allium species inhibit the growth of certain tumors. ... 

C/N in higher plants is 7-30 for the entire plant but 20-50 for photosynthetic organs, N/P uses to be 50-80 and C/S about 500 (stoichiometric ratios each). Both S and Se are partly bound into ligands (cysteine, methionine, selenocysteine, dimethyl selenide and many plant components such as those of Allium species including garlic), but likewise partly in weakly complexing anions like SO/ or SeO ", respectively (total S in leaves or needles is about 3 mg/g DM or 90 mmol/kg C/S 450 and N/S < 20). 

All possible combinations of methyl, propyl, allyl, and 1-propenyl disulfides (primarily), monosulfides, and trisulfides have been found among the volatile flavor components of onion (28,29, 30,31), garlic (32), caucas Allium victorialis) (33), and other Allium species 28) although proportions vary with species. These compounds are presumably derived from the corresponding thiolsulfinates. This is accomplished either by direct decomposition by an unknown mechanism with evolution of SO2 (32) or by interaction with cysteine to produce a mixed disulfide (15),... 

The TLC pattern of various drug samples can vary according to the extraction methods. Stored powdered drug samples of Allium species can contain more degradation or transformation products such a.s ajoens and cepaenes, shown as yellow-brown (Fig. 5) or grey-blue (Fig. 6) zone.s in the low R( range of the TLC. 

Detection of Allium species (yellow-brown zones in vis.). 

Sorption rates for the 13 plants studied ranged from 0.16 to 4.4, ug c h g" dry W t root. Leaf concentrations ranged from 4.1 to 130 pg g dry weight after 48 h. The five Allium species exhibited both the lowest sorption rates and the lowest leaf concentrations. Obviously, there are substantial differences in sorption rates and leaf concentrations among plant species. Frequently, greater than 90 % of the c contained in the tissue is soluble in water. If the soluble fractions are further fractionated by ultrafiltration, it appears that the majority of fc accumulated in tissues is in a form other than I cO. ITie data suggest that Ic accumulated by plants is predominantly incorporated into soluble plant macromolcculcs or eomplexed by plant metabolites (5.5]. 

Sulfate fertility, role in flavor intensity of onions, 46/,47-49 Supcreritical carbon dioxide, extraction of Allium species, 113-123 Supercritical fluid chromaiography-chemiluminescent nitrogen detection, 102,104/... 

The natural flavors from garlic (Allium sarivum), onion (A. cepa), and other Allium species, like those from many other common vegetables and fruits, are not present as such in the intact plants but are formed by cnaymatic processes when the plants are chewed or cut (49). Additional flavors, also considered natural, arc formed during cooking as a result of the thermal breakdown of the initial enzymatically produced flavorants in either an aqueous on nonaqueous (c.g., cooking oil) medium. If the breakdown products are unstable, other compounds can be formed, which can contribute to the aroma and taste of the food. 

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