Bitterness glycosides

Carduus aeaulis Thunb. C. crispus L. C. japonicus Franch. (Syn. Cirsium japonicum) Xiao Ji (Plumeless thistle) (leaf, stem) Essential oils, glycosides, bitter principle.49 Hemostatic. 

Gentiobiose (= 6-0-p-D- Punica granatum (Punicaceae) Widespread component of glycosides Bitter... 

Phytochemistry Leaves contain alkaloids, glycosides, bitter substances, sesquiterpene lactones (arctiopicrin and onopor-dopicrin), vitamin C and K, resins, titratable acids, sugars, tannins, terpenoids (taraxasteryl acetate), etc. Seeds contain alkaloids, acetates of lupeol and amyrin, and drying fatty oil (Khalmatov et al. 1984 Ul chenko et al. 1993 Khalilova etal.2004). 

Roots contain inulin and fructo-oligosacchar-ides glycosidic bitter principles (officina-lisnin-I and officinalisnin-II) P-sitosterol, sarsasapogenin, and steroidal glycosides (named asparagosides A to I, in order of their increasing polarity) asparagusic acid and others. 

Sahcyl alcohol [90-01-7] (saligenin, o-hydroxybenzyl alcohol) crystallizes from water in the form of needles or white rhombic crystals. It occurs in nature as the bitter glycoside, saUcin [138-52-3] which is isolated from the bark of Salix helix S. pentandra S. praecos some other species of willow trees, and the bark of a number of species of poplar trees such as Folpulus balsamifera P. candicans and P. nigra. 

Stevioside and rebaudioside A are diterpene glycosides. The sweetness is tainted with a bitter and undesirable aftertaste. The time—intensity profile is characteristic of naturally occurring sweeteners slow onset but lingering. The aglycone moiety, steviol [471 -80-7] (10), which is the principal metaboHte, has been reported to be mutagenic (79). Wide use of stevia ia Japan for over 20 years did not produce any known deleterious side effects. However, because no food additive petition has been presented to the FDA, stevioside and related materials caimot be used ia the United States. An import alert against stevia was issued by the FDA ia 1991. In 1995, however, the FDA revised this import alert to allow the importation and use of stevia as a diet supplement (80), but not as a sweetener or an ingredient for foods. Several comprehensive reviews of stevia are available (81,82). 

Another notable glycoside is amygdalin, which occurs in bitter almonds and in the kernels or pits of cherries, peaches, and apricots. Hydrolysis of this substance and subsequent oxidation yields laetrile, which has been claimed by some to have anticancer properties. There is no scientific evidence for these claims, and the U.S. Food and Drug Administration has never approved laetrile for use in the United States. 

All of the mono-O-methylated hexopyranosides are sweet, with only a trace of bitterness. The bitterness is more pronounced in the methyl glycoside derivatives, and this was attributed to the presence of two lipophilic centers (—OMe) in the methyl glycosides and only one in the a,a-trehalose analogs. ... 

Table X), sweetness is not normally observed for ethyl glycosides, and does not occur at all for sugars having larger aglycons these are either bitter or very bitter. ...

In terms of taste, the flavanone glycosides can be divided into two groups. The first group consists of compounds that are bitter. These are glycosides... 

The conversion of the bitter flavanone glycosides into those of the corresponding chalcones by alkali-catalyzed fission of the pyrone ring, and of the dihydrochalcone glycosides by hydrogenation thereof (see Scheme 1)... 

Bitter taste, like sweet taste, is exhibited by a very diverse group of chemical compounds. Because the bitter taste is generally regarded as unpleasant, and because it is often associated with such compounds as those alkaloids and glycosides that are harmful to man, detailed studies have been minimal. There is thus very little information available from which to deduce the chemical grouping common to those compounds eliciting the bitter response. 

A traditional system for the preparation of table olives, involves a treatment of the fresh fruit with a solution of NaOH to hydrolised the bitter glycoside oleuropein, followed by a lactic fermentation in brine. The modifications that take place on pectic polysaccharides of olives (Manzanilla variety) during this process was smdied. Processing induced a net loss of polysaccharides soluble in sodium carbonate and a paralel accumulation of water and Imidazole/HCl soluble polysaccharides. A general decrease of the apparent molecular weight of water and carbonate soluble polysaccharides was also detected. 

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