Haridutt K. Desai

Effect of diterpenoid alkaloids on cardiac sympathetic efferent and vagal afferent nerve activity

The diterpenoid alkaloid, lappaconitine, at a dose of 150 micrograms/kg (i.v.) increased cardiac vagal afferent nerve activity (16.2%) and reduced cardiac sympathetic efferent nerve activity (12.5%). A polar analog, N-deacetyllappaconitine, at this same dose, increased cardiac vagal afferent nerve activity (40%) and reduced cardiac sympathetic efferent nerve activity (23.5%). Both of these agents also reduced arterial blood pressure and heart rate. A larger dose of lappaconitine (300 micrograms/kg i.v.) produced the same changes in nerve activities and cardiac function as the lower dose. Two other structurally related agents, lycoctonine and aconine, failed to alter these variables in doses up to 300 micrograms/kg. These data suggest that certain diterpenoid alkaloids activate autonomic reflex receptors, including cardiac reflex receptors. The polar agent, N-deacetyllappaconitine, appears to be more effective on cardiac reflex receptors than the non-polar agent, lappaconitine. Such agents may be useful in the treatment of hypertension.

The structure of barbeline, an unusual C19-diterpenoid alkaloid from delphinium barbeyi huth

Abstract From the ethanolic extract of Delphinium barbeyi Huth, a novel C 19 -Diterpenoid alkaloid barbeline ( 4 ) has been isolated and its structure determined by spectroscopic data and an X-ray crystal diffraction study. Barbeline is the only example of an alkaloid containing a C(19)=N- azomethine group among the 230 naturally occurring C 19 -diterpenoid alkaloids. Two other new alkaloids, 6-acetyldelpheline and 6-deoxydelpheline, as well as the known alkaloids browniine, delphatine and glaucenine have also been isolated from this plant.

The structure and partial synthesis of delelatine, an alkaloid from Delphinium species

A new C-19-diterpenoid alkaloid designated as delelatine has been isolated from Delphinium elatum L. and D. tatsienense Franch. and its structure has been elucidated by spectroanalytical methods. Delelatine has been correlated with 14-acetyl-10-deoxydictyocarpine and synthesized from dictyocarpine, thus confirming its structure and stereochemistry.

Norditerpenoid alkaloids from the aerial parts of Aconitum balfourii Stapf

From the aerial parts of Aconitum balfourii Stapf nine norditerpenoid alkaloids: condelphine (1), bullatine C (2), neoline (3), isotalatizi- dine (4), 1-O-methyldelphisine (5), pseudaconitine (6), yunaconitine (7), bikhaconitine (8), and indaconitine (9), were isolated. The iden- tity of these alkaloids was determined by comparison of mp, tlc and ir spectra with those of authentic samples and the carbon-13 nmr spectra of 2, 5, 6, 7 and 8 with the published chemical shifts. Detailed nmr spectral studies ( 1 H, 13 C, 1 H homonuclear COSY, HETCOR, and selective INEPT) carried out on (1), (3), (4) and (9) have provided accurate chemical shift assignments for these alkaloids.

New alkaloids from Consolida hellespontica

From the aerial parts of Consolida hellespontica (Boiss.) Chater we have isolated the new diterpenoid alkaloids chellespontine (1) and azitine (4). The norditerpenoid alkaloid 1-O-methyldelphisine (7) has not been reported earlier as occurring in nature, and the aporphine alkaloid (+)-corydine (11) has been isolated for the first time in the Ranunculaceae family. Besides these, the known alkaloids delphinine (8), delphisine (9) and bullatine C (14-acetylneoline) (10) have been isolated from this plant. The structures of these alkaloids were established by chemical correlation and spectroscopic studies

An unusual epimerization of the α-OH-1 group of the norditerpenoid alkaloid delphisine

Abstract Solvolysis of delphisine in refluxing methanol gives 8-deacetyl-8- O -methyl-1- epi -delphisine. Similarly, hydrolysis of delphisine in boiling water affords 14- O -acetyl-1- epi -neoline and solvolysis of 8- O -acetylneoline in methanol gives 8- O -methyl-1- epi -neoline. The structures of the products have been proved by spectral data and comparison with authentic samples. For epimerization to occur, both a α-OH-1 and a OAc-8 group are necessary. Mechanisms for the epimerization are discussed.

The structure and absolute configuration of heterophylloidine

Abstract The structure and absolute configuration of heterophylloidine, a new C 20 -diterpenoid alkaloid isolated from Aconitum heterophylloides Stapf, have been determined with the aid of 13 C NMR spectral data and single-crystall X-ray analysis of the product obtained by treatment of heterophylloidine with aqueous hydrobromic acid.

Norditerpenoid and diterpenoid alkaloids from the roots of Aconitum nasutum Fisch ex Reichb

Investigation of the alkaloidal constituents of the roots of Aconitum nasutum led to the isolation and identification of a new diterpenoid alkaloid designated as trabzonine (1). Three known norditerpenoid alkaloids, lappaconitine (2), lycoctonine (3) and gigactonine (4), and two known diterpenoid alkaloids pseudokobusine (5) and septatisine (6) were also isolated. The structures of 1 and 5 were established by detailed analyses of 1H and 13C NMR data. The structure and absolute stereochemistry of pseudokobusine (5) was determined by an X-Ray crystal structure determination.

SEPARATION OF DITERPENOID ALKALOIDS BY HIGH PERFORMANCE CENTRIFUGAL PARTITION CHROMATOGRAPHY

Complex diterpenoid alkaloids of close Rf values have been separated by High Performance Centrifugal Partition Chromatography (HPCPC). Model LLB-M (Series 1000) by Sanki Laboratories Inc. was used for these separations. Especially highly polar (on Al2O3) alkaloids which could not be isolated by conventional methods using a solid support, owing to irreversible retention, could be isolated easily as this separation method can be used in the reverse phase mode by careful selection of the biphasic solvent system. The HPCPC instrument was found easy to handle, dependable, applicable to the entire range of polarity of diterpenoid alkaloids, and gave reproducible results. When some of the fractions furnished a mixture of minor alkaloids, the mixture was resolved by a quick separation technique such as separation on a Chromatotron and preparative TLC. In all, eight different mixtures of known as well as crude alkaloidal mixtures were separated and the results are reported here. Isolated pure known compounds were ...

Alkaloids of Aconitum balfourii Stapf

Three new norditerpenoid almkaloids, 8-O-methylveratroylpseudaconine (9), veratroylbikhaconine (10), and balfourine (1), have been isolated from Aconitum balfiourii, together with eight known alkaloids, pseudaconitine, veratroylpseudaconine, indaconitrine, ludaconitine, 8-deacetylyunaconitine, bikhaconitine, neoline, and chasmanine. The new structures were derived from physical and spectroscopic data and chemical correlations with alkaloids of established structures.