New Alkaloids

During a search for physiologically active compounds in South African plants, a new hasubanan ester acetal alkaloid, methylstephavanine (6), was isolated from Stephania abyssinica (19). The H-NMR spectrum of the new alkaloid 6 exhibited signals for one methylenedioxy, one N-methyl, and four methoxyl groups (19) (Table II). Its mass spectrum revealed the most abundant ion peak at m/z 229, indicating a close resemblance to the known hasubanan alkaloid, stephavanine (18). 

Basic hydrolysis of 6 afforded alcohol 19 and methyl veratrate. The H-NMR spectrum of 19 (Table II) revealed the presence of one methylenedioxy, one N-methyl, and two methoxyl groups. The mass spectrum (Table IV) exhibited the most abundant and significant ion peak at m/z 229 indicative of metaphanine-type cleavage. Treatment of an aqueous THF solution of stephavanine (18) with excess sodium hydride and methyl iodide gave N.O-dimethylstephine, a compound identical to alcohol 19. Thus, the structure of the new alkaloid 6 was established by chemical correlation with stephavanine (79). 

6-Dihydroepistephamiersine 6-acetate (7) was isolated from Stephania abyssinica as a homogeneous oil. The UV spectrum showed an absorption maximum at 286 nm, and the IR spectrum exhibited a band corresponding to an aliphatic ester carbonyl group at 1725 cm-1 (20). The H-NMR data are summarized in Table II. In chemical investigations, hydrolysis of 7 with barium methoxide gave an alcohol identical with 6-dihydroepistephamiersine (17), which on further treatment with mineral acid gave the known alkaloid, stephasunoline (17). Thus structure 7 was proposed for 6-dihydroepistephamiersine 6-acetate (20). 

Oxidation of aknadinine with silver nitrate gave a pair of dimeric compounds, one of which was identical to the naturally occurring bisaknadinine (8) and the other assumed to be a stereoisomer arising from an axial chirality concerning the mode of biphenyl linkage (21,22). It was impossible, however, to determine from ORD and CD measurements whether the isomer is of natural bisaknadinine (8). Therefore, unambiguous proof of the stereochemistry was achieved, using the X-ray diffraction method, and the 

Sodium borohydride reduction of aknadinine gave a pair of epimeric alcohols, one of which was found to be identical to natural epihernandolinol and the other identical to the known alkaloid hemandolinol (10) (28). As the structure of hemandolinol (10) had been proposed without resolution of the stereochemistry (28), the stereochemistry of epihernandolinol (9) was not definitely established (27). 

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Amongst products isolated from Heliotropium spathulatum (Boraginaceae) were 9 mg of a new alkaloid which gave a positive Ehrlich reaction with p-dimethylaminobenzaldehyde The molecular formula determined by mass spectrometry is CisH2sNOs. What is the structure of the alkaloid given the set of NMR results 54 Reference is useful in providing the solution to this problem. Conditions CDCI3, 9 mg per 0.3 ml, 25 °C, 400 MHz ( //), 100 MHz ( C). (a) HH COSY plot ... 

C. stenopetalus belong to group (c) and contain up to 0-4 per cent, of alkaloids mainly cytisine and methylcytisine with traces of anagyrine in some specimens of the second species. C. monspes-sulanus also belongs to group (c) and contains 0-9 per cent, of alkaloids chiefly methylcytisine with some cytisine and a new alkaloid monspessulanine (p. 146), probably of the lupanine group. (1946). 

From D. repandula Bick and Whalley have isolated two new alkaloids, repanduline and repandine, of which the former is also present in D. Dielsii Perkins. 

Calabash curare, probably from the middle Orinoco region, has also been investigated by Karrer and Schmid,who have isolated eight new alkaloids in addition to Wieland s C-curarine I. 

Like other alkaloids of this group, quinine forms molecular compounds with a variety of organic substances. With benzene and toluene it produces compounds of the formulae B. CgHg and B. C,Hg respectively, with phenol it gives the crystalline product B. CgHjOH, and similar combinations with polyhydric phenols, ethers, aldehydes and ketones are known. One of the most characteristic of these substances is cupreine-quinine, a combination of the two alkaloids, obtainable from cuprea bark, and at first regarded as a new alkaloid, and named homoquinine. ... 

Delphinium ajacis L. From the seed of this species Keller and Volker isolated two crystalline alkaloids which they named ajacine and ajaconine. Their work was reviewed by Hunter, who reported the presence of four alkaloids, viz., ajacine, ajaconine and new alkaloids ajacinine and ajaci-noidine (amorphous). Goodson described ajacine in detail (1944) and later reported the isolation of ajaconine and three more bases distinguished as B, C and D. According to Hunter, lycoctonine (p. 686) is probably also present. 

Heteronuclear two-dimensional /-resolved spectra contain the chemical shift information of one nuclear species (e.g., C) along one axis, and its coupling information with another type of nucleus (say, H) along the other axis. 2D /-resolved spectra are therefore often referred to as /,8-spectra. The heteronuclear 2D /-resolved spectrum of stricticine, a new alkaloid isolated by one of the authors from Rhazya stricta, is shown in Fig. 5.1. On the extreme left is the broadband H-decoupled C-NMR spectrum, in the center is the 2D /-resolved spectrum recorded as a stacked plot, and on the right is the con tour plot, the most common way to present such spectra. The multiplicity of each carbon can be seen clearly in the contour plot. 

Indenobenzazepines have been used as key intermediates for synthesis of rhoeadine, protopine, phthalideisoquinoline, and spirobenzylisoquinoline alkaloids. Several new alkaloids possessing an indenobenzazepine skeleton have been isolated, and they are presumably biosynthesized from proto-berberine alkaloids. 

Data (since 1976) cover the new alkaloids and their derivatives subsequent to the last review in this treatise (2). b Derivative from natural product. c After exchange with D20. 

Finally, the structure of oxostephasunoline (4) was confirmed by the following chemical correlation with several known hasubanan alkaloids. Heating the new alkaloid 4 in an ethanolic hydroxide solution gave 16-oxoprometaphanine (33), which on treatment with dilute hydrochloric acid yielded 16-oxometaphanine (33). Thus structure 4 was proposed for oxostephasunoline (4). As stated in Section I, the hasubanan alkaloids carrying a... 

Scheme 10.13).110 New alkaloids from ants, (3R, 5.S, 9fl)-3-butyl-5-(l-oxopropyl)indolizidine and (3R, 5R, 9/ )-3-butyl-5-(l-oxopropyl)indolizidine, are identified and synthesized as outlined in Scheme 10.14.111... 

In the course of chemical investigation on Tabernaemontana, Achenbach et al. (116) isolated from T. glandulosa, from Sierra Leone and Nigeria, two new alkaloids, tabemulosine (42) and 12-demethoxytabemulosine (43). 

Finally, the last new alkaloid belonging to this subtype was found in T. mocquerysii, besides (205)-l,2-dehydropseudoaspidospermidine 169, already discussed in Volume 17 of this series and (20R)-pseudoaspidospermidine 174 (147). The new compound, (205)-pseudoaspidospermidine (175, cI9h26n2, mp 89°C, [a]D +60°), was identical in all respects, except optical rotation, with the pseudoaspidospermidine (304, [ot]D-60°), obtained by chemical elaboration of (+)-catharanthine (305) (109). 

Continuing with the chemical investigation of stem bark of T. albiflora (Taber-na albiflora), Husson et al. (26, 27) isolated six new alkaloids possessing the 21-... 

Normal Series. After 1967, only one new alkaloid was isolated in the normal series the N-oxide of dihydrocorynantheine (54) (55). 

Alio Series. Only two members of alio series of alkaloids are known cory-nantheidine (61) and mitragynine (62). No new alkaloid has been isolated since 1967. 

Epiallo Series. Previously, only speciociliatine (63) was known as a cory-nantheine-type alkaloid having an epiallo skeleton. Two new alkaloids in this series were isolated during the last decade, i.e., epiallocorynantheine (64) from Uncaria attenuata (59) and 3-isocorynantheidine (65) from Mitragyna speciosa Korth. (58). 

After 1960, many new isolations of these bases were reported, much chemistry and biology has been added to the original body, and about 80 new alkaloids from the vegetable and animal kingdoms have joined the list. These are the reasons why it was felt that the time had come to update the preceding reviews. 

Three new alkaloids have been isolated from Nauclea officinalis Pierre ex Pitaxd naucleficine (630), nauclefoline (631), and nauclefidine (632) (391). 

Abstract Recently, we have investigated Aconitum cochleare Woroschin and obtained three new alkaloids cochleareine, acoleareine from the aerial parts of the plant and cochleareinine from the roots. Cochlearenine exhibited antioxidant activity against DPPH free radical scavenging assay. The cardio active effect of has also have been studied on isolated heart preparations. 

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