Miscellaneous Alkaloids

A number of alkaloids whose biogenetic origin has not yet been identified have been discovered in one or a few species of both large Solanales families and some of them turned out to be unique. They are listed in the following in chronological order with regard to their discovery or first detection in the corresponding 

The purine base triacanthine (215) occurs in the fruit pericarp 113), leaves 112,113), and seeds 113) of Holarrhena mitis. 

Neozeylanicine (216), CnHioN2C 2, mp 110°C, is a new naphthyridine alkaloid isolated from the timber of Neonauclea zeylanica (Rubiaceae) (124,125), A new monoterpene alkaloid, 65-hydroxy-7/ -methyl-6,7-dihydro-2,5-pyrindene-4-carboxymethyl ester (217), has also been isolated from the same plant (124). However, details of the structure elucidation of the latter alkaloid are not yet available. 

Of a total of 43 Sri Lankan plants from which alkaloids have been isolated, 17 are claimed to have applications in traditional systems of medicine (Table III). As stated in the Introduction, many of these investigations were not driven by the claims of medicinal properties. Interestingly, several bioactive alkaloids have been isolated from plants with no claims of any medicinal applications. 

The most comprehensive study of a Sri Lankan medicinal plant was that of Tabernaemontana dichotoma conducted by Perera and co-workers (89,126). A preliminary pharmacological assay of the crude aqueous 

There is a wide variety of metabolites containing nitrogen, which is produced by micro-organisms. The nitrogen atom (or atoms) most frequently is derived ultimately from an a-amino acid which also provides at least part of the carbon skeleton. Modifications to cyclic dipeptides are commonly encountered as secondary metabolites (Sections 7.3 and 7.4). In the case of the vastly important pharmaceuticals, the penicillins and cephalosporins (Section 7.6.5), a linear tripeptide is involved in biosynthesis. 

Tryptophan (7.25) serves as a precursor for a number of microbial metabolites. A notable example is the ergot alkaloids (Section 7.5.1). Other aromatic amino acids are involved in the biosynthesis of various metabolites. Their origins are through shikimic acid 7,78) (see Section 5.1). Shikimic acid itself, or a close metabolic relative, serves as a source for some metabolites, e.g. phenazines (Section 7.5.5) and the ansamycins (Section 7.6.1). For compounds like the latter, acetate and propionate are also important starting materials for biosynthesis. Another important part source for many metabolites is mevalonate, invariably as a C5 (dimethylallyl) unit. 

The picolonic part [as (7.75)] of proferrorosamine A 7.16) originates in lysine (and glutamic acid), being formed via picolinic acid (7.75) 

1 for further discussion of starter acetate). Nitrogen intercalates in this chain at some point in biosynthesis, and the substrate for this is suggested to be (7.27) [11]. 

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Miscellaneous Alkaloids. Stukimic acid (57) is a precursor of anthranihc acid (28) and, in yeasts and Escherichia coli (a bacterium), anthranHic acid (o-aminobenzoic acid) is known to serve as a precursor of tryptophan (26). A similar but yet unknown path is presumed to operate in higher plants. Nonetheless, anthranHic acid itself is recognized as a precursor to a number of alkaloids. Thus damascenine [483-64-7] (134), C qH NO, from the seed coats of JSHgella damascena has been shown (95) to incorporate labeled anthranHic acid when unripe seeds of the plant are incubated with labeled precursor. 

Lewis, J. R. 2001. Amaryllidaceae, muscarine, imidazole, oxazole, thiazole, peptide and miscellaneous alkaloids. Nature Product Reports, 18 95-128. 

The intention of the eighth volume of The Alkaloids was once again to provide a comprehensive annual survey of the alkaloid literature. It has not been possible, however, to include chapters on the Tropane Alkaloids and on Miscellaneous Alkaloids, and certain aspects of the chemistry of isoquinoline alkaloids have been omitted we expect to remedy these deficiencies by including a two-year coverage in Volume 9. 

Part 6. Miscellaneous alkaloids with the aspidospermine skeleton and their derivatives... 

Alkaloids derived from ornithine, arginine Pyrrolizidine alkaloids Miscellaneous alkaloids X X X X X ... 

Miscellaneous alkaloids Aconitine Amanitin Anabaseine Arecoline Batrachotoxin Capsaicine... 

Miscellaneous alkaloids Anabasine Teratogenic, crooked calf disease 35U52... 

Miscellaneous alkaloids Abikoviromycin Ageliferin Crinamine Cryptopleurine Sceptrin Didemnin Haemanthamine Hippeas trine... 

Lewis JR (1999) Miscellaneous alkaloids Amaiyllidaceae, Sceletium, muscarine, imidazole, oxazole, peptide and other miscellaneous alkaloids. Nat Prod Rep 16 389-416... 

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