Dioscorine

Dioscorine is bitter and poisonous it produces paralysis of the centra system, and, in general, behaves like picrotoxin. This action PPears to be correlated with the — 0—C = C- group, since on the... 

Dioscorine has also been found in D. hispida tubers by Zeyva and Gutierrez. ... 

Tropane Group. SolanaceOus Alkaloids, Convolvine and Allied Alkaloids, Dioscorine, Alkaloids of Coca Leaves (Erythroxylon coca). ... 

In Dioscorea hispida, Trigollenine is incorporated into the isoquinuclidine moiety of the alkaloid Dioscorine (208), as proved by a feeding experiment with [TOer/ y/- " C,2- H, H]trigollenine (88P3793). These results are consistent with the hypothesis for the biosynthesis of Dioscorine (208), Dumetorine and Dihydrodioscorine, which is presented in Scheme 68. 

Dioscorine.—Labelling of C-5, C-.10, and C-12 of dioscorine (2) by [l-14C]acetic acid8 indicates that C-5, C-6, C-9, C-10, C-ll, C-12, and C-13 derive from acetate. This leaves a cyclic C5N unit unaccounted for, which, from the wealth of evidence on the biosynthesis of similar systems (see previous Reports), one expects will arise from the amino-acid lysine via A piperideine (1), an expectation not realized since neither compound is satisfactorily incorporated into dioscorine (2).8... 

The evidence for dioscorine biosynthesis is consistent likewise with the intermediacy of (4) (see Scheme 1). The sequences of saturation and condensation leading to dioscorine, and also anatabine, cannot yet be specified, but are clearly well worth exploring. Of interest too, in the case of dioscorine, is the way in which the branched acetate chain originates (stepwise introduction of acetoacetate units in the course of the biosynthesis of the alkaloid ). 

Yams (make up the everyday diet for many in Africa. It is therefore surprising to learn that they contain a toxic substance called dioscorine(, which has convulsive properties and causes hepatic and renal failure [61,62]. The toxicity is related to the incomplete preparation of the food. 

Dioscorine, whiclr had been regarded as a tropane base, has been shown to be an isoquinuclidine (7) and will not be dealt with again. 

In a reaction scheme designed for the synthesis of dioscorine (2), a Mannich reaction involving cyclohex-2-enone (92), formaldehyde, and methylamine led to the formation of the ISQ 93 in addition to a small amount of the expected Mannich base 94 [2]. Evidently 94 underwent... 

On the other hand, two of the possible structural isomers (LXXIV, LXXV) (1 3, 1 4) of Ar,JV-dimethyl-i-butylcycloheptyIamine have been synthesized. The IR-curves were very close to those of the saturated Hofmann base CisH N none of them proved, however, to be identical with that of the base from dioscorine. Since configurations have not been taken into consideration, these data are not conclusive. Nevertheless, a new tentative formula has been suggested (84) which takes account of the formation of a >C = CHg group on decarboxylation of the hydroxy acid from dioscorine, i.e., that of the c-lactone of a tropine derivative with a j8-methyl-a,/3-butenoic acid side chain in... 

A more recent communication describes a somewhat different approach to the structural problem of dioscorine. Hydrogenolysis of the lactone led to a diol which on ozonolysis afforded glycolaldehyde and a hydroxy ketone. The latter underwent cleavage to acetone and another ketone, CgH sON, the IR-spectrum of which is more in accord with a five-membered than with a six-membered cyclic ketone. On this basis structure LXXVIa has been suggested for dioscorine (123). Racemic... 

CsHigON obtained from dioscorine. Thus the alkaloid seems to be a... 

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