Dihydroergotoxine alkaloids

The relative retention times of the decomposition products of the dihydroergotoxine alkaloids are given in Table 18.5. The influence of the injection port temperature on the decomposition of the alkaloids is illustrated in Figure 18.9. The reproducibility of the method is good, as can be seen from Table 18.6. 

STRUCTURES OF DIHYDROERGOTOXINE ALKALOIDS AND THEIR THERMAL DECOMPOSITION PRODUCTS14... 

Application of the method to the determination of the dihydroergotoxine alkaloids in commercial samples and pharmaceutical preparations were all carried out with the free base of the alkaloids since analysis of their salts cannot be performed without excessive decomposition. The mean dihydroergotoxine methane sulphonate content of five commercial samples was 95,2 2.9 %, including a mean dihydroergocomine content of 30.9 0.8 %, a mean dihydro-ergokryptine content of 32.8 2.1 % and a mean dihydroergocristine content of 31.5 3.5 %. Almost the same data were observed for dihydroergotoxine tablets obtained from two manufacturers. 

Szepesi, G. and Gazdag, M. (1976) Determination of dihydroergotoxine alkaloids by gas-liquid chromatography. J. Chromatogr., 122, 479 85. 

Today, 2-bromo-a-ergocryptine (bromocriptine) is the second (after dihydroergotoxine) most extensively used compound from the group of ergot alkaloids. 

Dihydroergotoxine, a mixture of dihydro-K-ergocryptine and three similar dihydrogenated peptide ergot alkaloids (ergoloid mesylates), has been promoted for many years for the relief of senility and more recently for the treatment of Alzheimer s dementia. There is no useful evidence that this drug has significant benefit. 

The ergotoxine alkaloid mixture also has oxytocic and vasoconstrictor activity but is only employed medicinally as the 9,10-dihydro derivatives dihydroergotoxine (co-dergocrine), a mixture in equal proportions of dihydroergocornine, dihydroergocristine, and the dihydroergocryptines (a- and p- in the ratio 2 1). In the case of these alkaloids, reduction of the double bond appears to reverse the vasoconstrictor effect, and dihydroergotoxine has a cerebral vasodilator activity. The increased blood flow is of benefit in some cases of senility and mild dementia, and helps to improve both mental function and physical performance. 

ERGOLOID MESYLATES (DIHYDROGENATED ERGOT ALKALOIDS DIHYDROERGOTOXINE)... 

Common Name Dihydroergotoxine Dihydrogenated ergot alkaloids Structural Formula ... 

Synonyms. Co-dergocrine Methanesulphonate DEA DHAE Dihydroergotoxine Mesylate Dihydrogenated Ergot Alkaloids Hydrogenated Ergot Alkaloids. 

A micellar electrokinetic capillary chromatographic (MECC) method to separate 17 dihydroergotoxines, aci-alkaloids, and oxidation products has been described [103]. The authors used novel cationic dimeric (Gemini) surfactants such as l,3-bis(dodecyl-W,N-dimethyl ammonium)-2-propanol and l,3-bis(te-tradecyl-N,N-dimethyl ammonium)-2-propanol for the separation in less than 8 min. 

Fig. 4.9) (115). Each component of the ergotoxine alkaloids ccmtains a tripeptide moiety, with two of three amino acids (u-valine and L-proline) being in common in all of the compounds, while the third amino acid differs (115). The ergotoxines 160-163 isolated from natural sources can be hydrogenated to yield the 9,10-dihydroergotoxines 164-167, composed of dihydroergocomine... 

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