Mandelonitrile glycosides

Mandelonitrile glycosides (cyanoglycosides) e.g. amygdalin, pninasin, taxiphyllin, vicianin... 

Note The colors of the chromatogram zones produced by the mandelonitrile glycosides change with time Those of the D-isomers turn steel blue within an hour, while the 1 isomers turn reddish-brown during this time. It is possible to distinguish between D-and L-forms on the basis of these typical color differences and color changes. Both isomeric forms have a dark brown color after about 24 hours. 

The detection limits for mandelonitrile glycosides are 3 to 5 pg substance per chromatogram zone. 

Palladium hydroxide-barium sulfate Cleavage of mandelonitrile glycosides... 

Benzaldehyde Cyanohydrin. This cyanohydrin, also known as mandelonitrile [532-28-5] is a yellow, oily Hquid, insoluble in water, but soluble in alcohol and diethyl ether. Mandelonitrile is a component of the glycoside amygdalin [29883-15-6] a precursor of laetdle [1332-94-7] found in the leaves and seeds on most Prunus species (plum, peach, apricot, etc). In 1832, mandelonitrile was the first cyanohydrin to be synthesized. 

Salicin is an (9-glycoside of a phenol, namely salicyl alcohol. Salicin is a natural antipyretic and analgesic found in willow bark, and is the template from which aspirin (acetylsalicylic acid, see Box 7.13) was developed. Prunasin from cherry laurel is an example of a cyanogenic glycoside, hydrolysis of which leads to release of toxic HCN (see Box 7.7). It is the (9-glucoside of the alcohol mandelonitrile, the trivial name for the cyanohydrin of benzaldehyde. It is the further hydrolysis of mandelonitrile that liberates HCN. 

A number of plants are capable of producing HCN by the breakdown of cyanogenic glycosides. Oxynitrilase catalyzes the release of HCN from (i )-mandelonitrile (Equation (23)). 

Four cyanogenic glycosides (amygdalin, linamarin, prunasin, mandelonitrile) were extracted from apricots and separated on a C g column (2 = 200 nm or pulsed amperometric detection, ] = 0.00 V for 240 ms, = 0.60 V for 60 ms, ) = —0.80 V for 60 ms). For the amperometric analysis, a 0.5 M NaOH solution was fed into the effluent postcolumn. An isocratic 12 min 82/12 water/acetonitrile run or an 8-min 100/0- 40/60 water/acetonitrile gradient was used [1259]. Baseline resolution was achieved using the gradient... 

Since the amygdalin may be synthesized 41) from hepta-O-acetyl-gentiobiosyl bromide and ethyl DL-mandelate by the procedure outlined above, the glycoside is undoubtedly D(levo)-mandelonitrile iS-D-gentio-bioside 42),... 

The configuration at the benzylic centre of naturally occurring and synthetic glycosides of mandelonitrile can be assigned by n.m.r. spectroscopy, since the chemical shifts of the methine and anomeric protons depend on the configuration at the benzylic centre. 

In beetles and millipedes, which do not live on plants that produce cyanogenic glycosides, the compound is almost certainly made by the insect or arthropod itself. In millipedes mandelonitrile is stored in an inner chamber of their defensive glands, which is separated from the outer chamber which holds enzymes that catalyze the breakdown of mandelonitrile to benzaldehyde and HCN. A muscle controls the valve between the two chambers. 

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