I= STUDIES ON THE CHEMICAL CONSTITUENTS OF DELPHINIUM DENUDATUM AND BIOSYNTHESIS OF COLCHICUM ALKALODIS
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Title of Thesis
STUDIES ON THE CHEMICAL CONSTITUENTS OF DELPHINIUM DENUDATUM AND BIOSYNTHESIS OF COLCHICUM ALKALODIS

Author(s)
Amber Nasreen
Institute/University/Department Details
University of Karachi/H.E.J Research Institute of Chemistry
Session
1998
Subject
Chemistry
Number of Pages
314
Keywords (Extracted from title, table of contents and abstract of thesis)
delphinium denudatum, colchicum alkalodis, colchicum autumnale plants, colchicine, panicutine , vilmorrianone, atisinium chloride, bicolorine, denudatine

Abstract
The work embodied in this dissertation comprises two parts. Part-A deals with investigations on the biosynthesis of colchicines in Colchicum autumnale plants. The work involved employing radiolabelled precursors in order to optimize the physiological parameters for feeding experiments by using different parts of the plant, different species of Colchicum and different developing stages of the seeds of C. autumnale. The 13C-labelled precursors were synthesized and applied, and the isolated colchicines was subsequently subjected to 13C-NMR analysis in order to finally allocate the exact site of enrichment after biosynthesis. The incorporation results showed that the (S) autumnaline serves as specific precursor of colchicines in Colchicum autumnale seeds.

Studies on colchicines (32) biosynthesis revealed an enzymic complex which was isolated and characterized. It specifically catalyses a particular intramolecular oxidative phenolic coupling reaction in the biosynthetic pathway. In this case autumnaline was directly coupled to furnish isoandrocymbine, a dienone type compound.This oxidative phenolic coupling reaction was found to be catalysed by a highly region-and stereospecific microsomal bound cytochrome P-450 enzyme.The reaction was, furthermore, strictly dependent on NADPH and molecular oxygen. The Km value for (R, S) autumnaline was determined as 37.0 ┬ÁM.

Part-B of the thesis is concerned with the phytochemical investigations on the roots of Delphinium denudatum which resulted in the isolation and characterization of new diterpenoid alkaloids. The structure of 8-acetl heterophyllisine (219), a new heteratisine-type diterpenoid base, was elucidated with the assistance of extensive spectroscopic studies and confirmed by an X-ray diffraction method. In addition, five known compounds were also isolated from D. denudatum for the first time whereas the X-ray structures of 3-hdroxy-2-methyl-4-H-pyran-4-one (220) and panicutine (221) are also reported for the first time. One known compound, denudatine (214) has also beenisolated from the same species.

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3610.47 KB
S. No. Chapter Title of the Chapters Page Size (KB)
1 0 Contents
126.43 KB
2 1 Introduction 1
283.01 KB
3 2 Material and Methods 26
186.38 KB
  2.1 Plant Materials 26
  2.2 Instruments 27
  2.3 Special chemicals 28
  2.4 Reference alkaloids 29
  2.5 Application experiments 30
  2.6 Production of cell free enzyme 31
  2.7 Enzyme tests 33
  2.8 Chromatographic methods 35
  2.9 Spectroscopic methods 39
  2.10 Radioactivity determination 39
4 3 Results and Discussion 42
1294.21 KB
  3.1 Chemical synthesis of heavy isotope labeled precursors 46
  3.2 Chemical synthesis of unlabelled precursors 53
  3.3 Purification of mammalian catechol -O methyltransferase 55
  3.4 Enzymatic synthesis of potential precursors 59
  3.5 Studies on Colchicine 61
  3.6 Optimization of the application system 68
  3.7 Investigationof colchicines biosynthesis 80
  3.8 Autoradiography with tritium labeled (R.S)- autumnaline (20d ) 89
  3.9 Enzymatic investigation of colchicines biosynthesis 98
5 4 Introduction 146
402.79 KB
  4.1 Spectral studies on diterpenoid alkaloids 172
6 5 Biosynthesis 183
212.39 KB
  5.1 Biosynthesis of terpenoids 186
  5.2 Biosnthesis of diterpenoids 191
7 6 Results and Discussion 204
970.34 KB
  6.1 8-Acetylheterophyllisine (219) 205
  6.2 3-Hydroxy-2-methyl-4-H-pyran-4-one (220) 222
  6.3 Panicutine (221) 229
  6.4 Vilmorrianone (222) 239
  6.5 Atisinium chloride (114) 247
  6.6 Bicolorine (Alkaloids-B) (223) 255
  6.7 Denudatine (214) 258
8 7 Experimental 267
341.55 KB
9 8 References 299
163.89 KB