Alkaloids: Chemical and Biological Perspectives (eBook)

S.W. Pelletier (Herausgeber)

eBook Download: PDF | EPUB

1998 | 1. Auflage
387 Seiten
Elsevier Science (Verlag)
978-0-08-052701-7 (ISBN)

Infos

Acronycine, a potent antitumor agent, was discovered in the bark of the small Australian Rutaceous tree, Acronychia baueri Schott. This new work presents a comprehensive survey of the isolation, structure determination, methods of synthesis, and the biological properties of acronycine, as well as an account of natural and synthetic analogues of acronycine, and their biological properties.
Solanum alkaloids were reviewed in 1990 and this book surveys the new developments (isolation procedures, structural elucidation methods) and critically updates earlier reviews. In addition it presents the interesting chemistry and synthesis of cyclopeptide alkaloids. These cyclopeptide alkaloids have been isolated from ascidians, sea hares, and cyanobacteria. Also included are reviews of the use of the functionalized lactam, pyroglutamic acid, as a chiral template for the synthesis of alkaloids. The second review examines the on-line coupling of capillary electrophoresis (CE) and mass spectrometry (MS) for the analysis of alkaloid mixtures. Finally a review of oxygenated analogs of the alkaloid Marcfortine for their potent antiparasitic activity is included at the end of this work.
Each chapter in this volume has been reviewed by at least one expert in the field. Indexes for both subjects and organisms are provided.

Inhalt

Front Cover 1
Alkaloids: Chemical and Biological Perspectives 4
Copyright Page 5
Contents 18
Chapter 1. Acronycine-type Alkaloids: Chemistry and Biology 20
Chapter 2. Solanum Steroid Alkaloids – an Update 122
Chapter 3 . Synthesis and Structure-Activity Studies of Lissoclinum Peptide Alkaloids 206
Chapter 4. Pyroglutamate as a Chiral Template for the Synthesis of Alkaloids 248
Chapter 5. Analysis of Alkaloids by Capillary Electrophoresis and Capillary Electrophoresis – Electrospray Mass Spectrometry 308
Chapter 6. Oxidation of Anthelmentic Marcofortine A, an Indole Alkaloid 362
Subject Index 394
Organism Index 404

Textauszug

Chapter Two

Solanum Steroid Alkaloids - an Update

Helmut Ripperger    Institute of Plant Biochemistry D-06120 Halle (Saale) Germany

1 INTRODUCTION

The chemistry of Solanum steroid alkaloids and their occurrence in the plant kingdom have been reviewed in 1953 and 1960 by Prelog and Jeger in Volumes 3 [1] and 7 [2], in 1968 by Schreiber in Volume 10 [3] and 1981 by Ripperger and Schreiber in Volume 19 [4] of The Alkaloids (Academic Press). Since then there has been considerable progress in this field, especially concerning isolation procedures, e.g. the use of reverse-phase chromatography, and structure elucidation methods, e.g. the application of two-dimensional nuclear magnetic resonance spectroscopy. Interesting results have been obtained when the hitherto more or less neglected plant roots were studied. Our present purpose is to describe further advances in a short form and to critically update the earlier reviews.

Solanum steroid alkaloids generally occur as glycosides, the aglycones of which possess the C27-carbon skeleton of cholestane and belong to the following five groups: the spirosolanes, e.g. solasodine (1); the epiminocholestanes, e.g. solacongestidine (2); the solanidanes, e.g. solanidine (3); the solanocapsine group, e.g. solanocapsine (4); the 3-aminospirostanes, e.g. jurubidine (5). These compounds occur in Solanaceae and some in Liliaceae. Alkaloids with C-nor-D-homo ring skeleton or other alterations of the cholestane ring system found in Liliaceae were not included.

The present review includes a survey of the occurrence of Solanum steroid alkaloids isolated since 1981 (Table 3) as well as of the physical constants of new aglycones (Table 4) and alkaloid glycosides (Table 5). These Tables are supplements to the corresponding compilations in previous Volumes of The Alkaloids (Academic Press) [3,4].

Recent papers have shown that Solanum species often contain complex mixtures of steroid alkaloid glycosides, which still present separation difficulties. Therefore, many of the older publications using less sophisticated technique are worth repeating.

2 GENERAL

Progress in the isolation procedures rested essentially on the development of chromatographic techniques. Whereas normal-phase chromatography separated glycoalkaloids mainly according to their carbohydrate portions, retention of reverse-phase chromatography [5–8] strongly depended on the aglycones. This means that we have available two independent separation methods, which can be applied consecutively. Especially useful is high-performance liquid chromatography. Some selected methods are listed in Table 1. Even saturated and 5,6-unsaturated compounds could be separated [9]. Table 2 indicates the dependence of the retention times of glycoalkaloids on the structure of the aglycones.

Table 1

High Performance Liquid Chromatography of Solanum Steroid Glycoalkaloids and Aglycones

Column

Mobile phase

Ref.

Zorbax NH2

Tetrahydrofuran-acetonitrile-water (11:5:4)

[10]

“Carbohydrate Analysis” (alkylamine packing)

Acetonitrile-water (pentanesulphonic acid) (83:17)

[11]

Supelcosil LC-18-DB

Acetonitrile-methanol (ethanolamine) (3:2)

[9]

Alltech C18

Acetonitrile-water (sodium dodecyl sulphate, with H3PO4 to pH 2.3-2.5) (17:3)

[12]

Resolve C18, Ultrasphere C18, Pecosphere C18, Supelcosil C18

Acetonitrile-ammonium phosphate buffer pH 3.5 (7:13) or pH 2.5 (3:2)

[13]

Nucleosil 125/8/4 RP-18

Acetonitrile-phosphate buffer pH 3.4 (27:73 to 33:67)

[14]

Eurosil Bioselect C-8

Methanol-ammonium phosphate buffer pH 3 (3:2 or 1:1), acetonitrile-phosphate buffer pH 3 (1:3)

[7,15]

Table 2

Relative Retention Times of Solanum Steroid Glycoalkaloids (Relative to Solanine, Eurosil Bioselect C-8, Methanol-Ammonium Phosphate Buffer pH 3a)

23-Hydroxyspirosolanes

(23S)-23-Hydroxyisoanguivine

0.51

(23S)-23-Hydroxyanguivine

0.55

22,26-Epiminocholestanes

3-O-(β-D-Glucopyranosyl)etioline

1.00

Solanidanes

Solanine

1.00

Demissine

1.00

Chaconine

1.11

Spirosolanes

Xylosyl-β-solamarine

1.29

Xylosylsolamargine

1.35

Solasonine

1.46

Isoanguivine

1.58

Robustine

1.69

Solamargine

1.71

Tomatine

1.80

β1-Solamargine

1.81

Anguivine

1.82

N-Hydroxyspirosolanes

N-Hydroxyrobustine

3.27

N-Hydroxysolamargine

3.58

25-Acetoxyspirosolanes

25-Acetoxyrobustine

6.70

a Experimental conditions for analytical HPLC see ref. [7].

Especially useful for structure elucidation was the application of nuclear magnetic resonance methods, in particular two-dimensional measurements. The complete 1H and 13C spectral assignments have been reported for e.g. tomatidine, tomatine [16], solasodine [17] and many other alkaloids mentioned in Chapter 4. One-dimensional 13C studies have been described for epiminocholestanes with a 4-keto function [18] and solanidanes [19]. Detailed reviews of NMR data of steroidal alkaloids are available [20,21]. These measurements now offer a potent nondegradative method for establishing the whole structure of a glycoalkaloid. But it should be mentioned that the structure elucidation of the carbohydrate moiety cannot be regarded as rigorous, if it is based only on the comparison of the 13C NMR signals with those of (substituted) monosaccharide units, because the chemical shifts not only depend on the sugar itself and the type of branching, but also on the neighboring sugar moieties; e.g. for C(1) of a terminal α-rhamnopyranose the values δ 100.3 (robustine [22]) or 102.9 (solamargine [7]), for C(5) of this moiety δ 69.1 (robustine [22]) or 70.5 (solamargine [7]), for C(1) of a terminal β-xylopyranose δ 104.8 (tomatine [16]) or 107.5 (xylosylsolamargine [15]), for C(2) δ 74.6 (anguivine [23]) or 75.6 (xylosylsolamargine [15]) were detected. For C(4) of a 2,3-branched β-galactopyranose δ 70.4 (solasonine [7]) or 71.0 (isoanguivine [23]) were found (all measurements in pyridine-d5). If, however, the signals of the whole carbohydrate ensemble are known, then identical shifts of an unknown glycoside indicate identical oligosaccharide structure.

Mass spectral methods suitable for polar compounds such as steroid alkaloid glycosides are fast atom bombardment (FAB) [24], liquid secondary ion (LSI), laser desorption/Fourier transform (LD/FT) [25] and electrospray ionization (ESI) mass spectrometry [14]. FAB or LSI mass spectra of glycoalkaloids exhibit strong [MH]+, [aglycone + H]+ and ions arising by sequential loss of sugars, whereas ESI mass spectra are described to display mainly [MH]+ and [aglycone + H]+ ions [14]. Electron impact (EI) mass spectra of aglycones display useful fragments for the different alkaloid types: m/z 138 and 114 for spirosolanes [26], m/z 125 for 22(N)-unsaturated 22,26-epiminocholestenes [27], m/z 98 for saturated 22,26-epiminocholestanes [28,29], m/z 140 and 111 for 23,26-epiminocholest-23(N)-en-22-ones [30,31], m/z 204 and 150 for solanidanes [26], m/z 130, 112 and 84 for alkaloids of the solanocapsine type [32] and m/z 139 and 115 for 3-aminospirostanes [33,34]. Further mass spectrometric studies dealt with solanidane N-oxides [35] or with the investigation of tomatine at the femtomole level by means of four-sector tandem mass spectrometry and scanning-array detection [36].

X-ray analysis has confirmed the structure of solasodine [37]. Further...

Produkt-Details

• Erscheint lt. Verlag: 23.4.1998
• Sprache: englisch
• Themenwelt: Sachbuch/Ratgeber
• Themenwelt: Medizin / Pharmazie ► Gesundheitsfachberufe
• Themenwelt: Medizin / Pharmazie ► Medizinische Fachgebiete ► Pharmakologie / Pharmakotherapie
• Themenwelt: Naturwissenschaften ► Biologie ► Biochemie
• Themenwelt: Naturwissenschaften ► Chemie ► Organische Chemie
• Themenwelt: Naturwissenschaften ► Physik / Astronomie ► Angewandte Physik
• Themenwelt: Technik
• ISBN-10: 0-08-052701-9 / 0080527019
• ISBN-13: 978-0-08-052701-7 / 9780080527017