Showing papers on "Indole alkaloid published in 1983"

Secologanin, a Biogenetic Key Compound—Synthesis and Biogenesis of the Iridoid and Secoiridoid Glycosides

Abstract: The monoterpene glycoside secologanin is a key intermediate in the biosynthesis of most indole, cinchona, ipecacuanha, and pyrroloquinoline alkaloids, as well as of simple monoterpene alkaloids. More than a thousand alkaloids are formed from secologanin in vivo; this represents almost a quarter of this large group of natural products. It is also the parent compound of the secoiridoids. Many of the compounds derived from secologanin display a high degree of biological activity and are employed as pharmaceuticals, e.g., the dimeric indole alkaloid leurocristine (vincristine) which is used very successfully in the treatment of acute leukemia. A knowledge of the biosynthesis and biological reactions of secologanin provides a sound basis for the biosynthesis-orientated classification of numerous natural products and the taxonomy of many plants. Secologanin and structurally related substances can be synthesized in a few steps by stereocontrolled photochemical and thermal cycloadditions. Its biomimetic reaction with amines and amino acids yields other natural products and compounds of pharmacological interest.

Catharanthus alkaloids XXXVII. 16-Epi-Z-isositsirikine, a monomeric indole alkaloid with antineoplastic activity from Catharanthus roseus and Rhazya stricta.

Abstract: 16-Epi-Z-isositsirikine (1) has been isolated from the leaves of Catharanthus roseus and Rhazya stricta and identified through a combination of spectral interpretation and chemical correlation. The compound displayed antineoplastic activity in the KB test system in vitro and the P-388 test system in vivo.

Characterization of Polyneuridine Aldehyde Esterase, a Key Enzyme in the Biosynthesis of Sarpagine/Ajmaline Type Alkaloids

Abstract: Polyneuridine aldehyde esterase (PNA-esterase) was isolated and partially purified from cell suspension cultures of RAUWOLFIA SERPENTINA B ENTH. The exceptionally high substrate specific enzyme catalyses the conversion of the monoterpenoid C 10- into the C 9- unit at the stage of polyneuridine aldehyde during the biosynthesis of sarpagine/ajmaline type alkaloids. The enzymatically formed compound is the new, labile indole alkaloid 16-epivellosimine. It is this alkaloid which functions as a branch point of the biogenetic routes leading to sarpagan and ajmalan type alkaloids. PNA-esterase occupies a key position in the biosynthesis of both alkaloid groups.

The Sarpagine-Ajmaline Group of Indole Alkaloids

Abstract: The indole alkaloids of the sarpagine-ajmaline type comprise one of the largest groups of structurally related indolic natural products: 45 com-pounds of the sarpagine type, 53 of the ajmaline type, and four bisindole alkaloids containing one or the other. The compounds are widely dispersed in 25 plant genera, mainly in Apocynaceae, the most important genus being Rauwolfia (1). Some 100 plant species are currently known to contain members of this vast group of alkaloids.

Notizen: The Isolation and Structure of Hyderabadine, a New Indole Alkaloid from Ervatamia coronaria

Abstract: A new indole alkaloid, hyderabadine, has been isolated from the leaves of Ervatamia coronaria to which structure 1 has been assigned.

Superoxide response induced by indole alkaloid tumor promoters

Abstract: The pleiotropic effects of the potent tumor promoter 12-0-tetradecanoyl-phorbol13-acetate (TPA) upon cell growth and function are well known.’ TPA is also a strong inflammatory agent that activates the reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase of human neutrophils inducing superoxide anion (02:) production.’ Previous work in our laboratory, by Goldstein et al., shows an apparent positive association between tumor promotion and 02; formation for phorbol esters and analogues of phorbol esters3 Slaga has shown that other oxygen radical-producing substances may be implicated in tumor promotion as we1L4 Teleocidin (from Streptomyces mediocidicus) and lyngbyatoxin A, debromoaplysiatoxin, and aplysiatoxin (from the marine blue-green alga Lyngbya majuscula) have been shown to have an inflammatory effect on animal skin.’ Lyngbyatoxin A and debromoaplysiatoxin cause dermatitis or “swimmer’s itch” in humans.6 All of these compounds have shown an ability to induce superoxide anion production in human polymorphonuclear leukocytes ( PMNs) in comparable amounts to TPA. Superoxide anion production increased to a peak amount for various molar quantities of these materials, with debromoaplysiatoxin and aplysiatoxin apparently producing greater amounts of 02; than did TPA and teleocidin. Lyngbyatoxin A produced much less of a respiratory burst after a 10-minute incubation with the same number of cells, even at higher molar concentrations. These substances were tested for their ability to produce 0’; in PMNs by the reduction of ferricytochrome C, which was inhibited by superoxide dismutase.’ Whole blood was obtained and sedimented in 1% dextran ( M , 240,000) at 25°C for 45 minutes. After osmotic shock to remove red cells, PMNs were resuspended in phosphate-buffered saline (PBS) (Ca” and Mg’+ free) a t a cell concentration of 1 06I 07/mi. Dose-response curves for each compound were done from 1 ng/ml to several hundred ng/ml. The results of these tests, plotted as molar quantities x lo-’ on semilog scale, can be seen in FIGURE 1. All materials (teleocidin B, lyngbyatoxin A, aplysiatoxin, debromoaplysiatoxin, and TPA) showed a response in the cells, and a production of 0,:. For all compounds, except lyngbyatoxin A, the range of 0.5-1 .O x lo-’ M showed a sharp rise in the stimulation of 0,; production. Lyngbyatoxin seemed to show a similar rise over a range of 4-9 x lo-’ molar, or a t least a fivefold greater amount.