Rauwolfia alkaloids rescinnamine

In the class of the butyrophenones, which has yielded a number of interesting psycho-active agents [119] - chiefly as a result of research done in the Janssen laboratories-two hypotensive compounds are also worth mentioning. They are the co-piperidino-butyrophenone (XII)-which, combined with the Rauwolfia alkaloid rescinnamine and the benzyl-piperazine trimetazidine, is marketed... 

Rescinnamine, a rauwolfia alkaloid with peripherally acting adrenergic-blocking effects (1 mg p.o. daily), is used in mild to moderate hypertension. 

The pharmacological properties of deserpidine are similar to those of reserpine, causing sedation and tranquilization. Toxic effects from high doses include drowsiness, depression, nansea, diarrhea, abdominal cramps, and hypotension. It is less toxic than reserpine. However, the poisoning effects may be greater than those of other Rauwolfia alkaloids, such as rescinnamine. An oral LD50 value in mice is 500 mg/kg. 

In 1918 the traditional Indian remedy rauwolfia was reported to be useful in the treatment of hypertension. Reexamination of this material led to the isolation of reserpine (28 R1 = Me, R2 = 3,4,5-trimethoxybenzoyl) which was shown in 1952 to have hypotensive and tranquilizing effects. Other alkaloids such as deserpidine (28 R1 = H, R2 = 3,4,5-trimethoxybenzoyl) and rescinnamine (28 R1 = Me, R2 = 3,4,5-trimethoxycinnamoyl) were later isolated. They are useful when alternative, more potent drugs are not well tolerated. 

Rescinnamine (Moderil) is an alkaloid of the alseroxylon fraction of Rauwolfia root. Syrosingopine (Singoserp) is a preparation made from reserpine by hydrolysis and... 

The occurrence of reserpine has been reported from all Rauwolfia species, with the exception of about half a dozen in which it is probably present in minute amounts. Renoxidine, the A-oxide of reserpine, has been isolated from R. vomitoria, R. serpentina, and R. canescens, and it may not be a natural product, since it could have been derived by autoxi-dation of the tertiary base which is abundant in these plants. If it was an artifact, the occurrence of other analogous A-oxides should have been noted, but so far the only other recognized case is raujemidine A-oxide, which is found along with the parent alkaloid, raujemidine (a minor base of R. canescens). In contrast to reserpine, deserpidine and rescinnamine are of restricted distribution, each being recognized so far in about ten species only. 

The root of Rauwolfia serpentina (snakeroot) contains numerons alkaloids, of which reserpine and rescinnamine are said to be the most active as hypotensive agents (1). 

This alkaloid is similar to reserpine except that the reserpic acid moiety of the molecule is esterified with trimethoxycinnamic acid rather than with trimethoxybenzoic acid. A non-aqueous titration similar to that given above is applicable (1 ml 0 05N 0-03174 g), or the colorimetric nitrite procedure may be applied. If the sample is thought to be contaminated with some of the other alkaloids of rauwolfia (less weakly basic), an extraction procedure can be applied followed by colour development as in the recommended method above. An aliquot of a suitable extract is diluted with 0-5N sulphuric acid and the aqueous ethanol is then extracted with trichloroethane which is discarded. The rescinnamine is then separated from other alkaloids by extracting the acid solution with chloroform and a suitable aliquot of the chloroform solution, containing 100 to 300 fxg of rescinnamine is evaporated and used for the colour development stage. The rescinnamine content is obtained from a standard curve prepared using a solution of rescinnamine in 95 per cent ethanol. 

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