Seconda chemical a ary metabolites from natural sour and pharmacological characteriz Dott.ssa ...

243 Pages·2010·8.47 MB·English

by  Carmen Festa

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FACOLTÀ DI FARMACIA

DOTTORATO DI RICERCA IN
“SCIENZA DEL FARMACO”
XXIII CICLO 2007/2010

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cchheemmiiccaall aaaanndd pphhaarrmmaaccoollooggiiccaall cchhaarraacctteerriizzzzaattiioonn..

DDootttt..ssssaa CCaarrmmeenn FFeessttaa

TTuuttoorr CCoooorrddiinnaattoorreeee
Prof. F. ZZoolllloo PPrrooff.. ssssaa MM..VV.. DD’’AAuurriiaa

In everything I seek to grasp
The fundamental:
The daily choice, the daily task,
The sentimental.
To plumb the essence of the past,
The first foundations,
The crux, the roots, the inmost hearts,
The explanations.
And, puzzling out the weave of fate,
Events observer,
To live, feel, love and meditate
And to discover.

In ogni cosa ho voglia di arrivare
sino alla sostanza.
Nel lavoro, cercando la mia strada,
nel tumulto del cuore.
Sino all’essenza dei giorni passati,
sino alla loro ragione,
sino ai motivi, sino alle radici,
sino al midollo.
Eternamente aggrappandomi al filo
dei destini, degli avvenimenti,
sentire, amare, vivere, pensare
effettuare scoperte.

Boris L. Pasternak

Index
INDEX

ABSTRACT ................................................................................................ I
PRESENTAZIONE DEL LAVORO SVOLTO .................................. III

INTRODUCTION ..................................................................................... 1

CHAPTER 1
RESEARCH STEPS................................................................................... 7
1.1 Isolation procedure of new compounds ............................................. 7
1.2 Structural determination methods .................................................... 11
1.2.1 Mass spectrometry ...................................................................... 11
1.2.2 Nuclear Magnetic Resonance Spectroscopy ............................ 13
1.3 Determination of stereochestry ......................................................... 15
1.3.1 Scalar and spatial NMR couplings ........................................... 15
1.3.2 Murata’s method ......................................................................... 17
1.3.3 Marfey’s method ......................................................................... 23

CHAPTER 2
PORIFERA ............................................................................................... 29
2.1 Metabolites isolated from sponges ................................................... 34
2.1.1 Macrolides ................................................................................... 35
2.1.2 Terpenes ....................................................................................... 37
2.1.3 Sterols ........................................................................................... 38
2.1.4 Cyclic peptides ............................................................................ 41

CHAPTER 3
COSCINODERMA MATHEWSI ......................................................... 45
3.1 Isolation of Coscinolactams A and B ............................................... 47
3.2 Structure determination of Coscinolactam A .................................. 48
3.3 Structure determination of Coscinolactam B .................................. 50
3.4 Pharmacological activity .................................................................... 52
Index
CHAPTER 4
THEONELLA SWINHOEI ................................................................... 57
4.1 Isolation and purification ................................................................... 59
4.2 Solomonsterols .................................................................................... 60
4.2.1 Solomonsterol A ......................................................................... 61
4.2.2 Solomonsterol B .......................................................................... 63
4.2.3 Pharmacological activity ............................................................ 64
4.2.4 PXR agonism ............................................................................... 66
4.2.5 Docking studies ........................................................................... 68
4.3 The family of perthamides ................................................................ 71
4.3.1 Perthamide C ............................................................................... 71
4.3.2 Perthamide D ............................................................................... 81
4.3.3 Perthamide E and its analogue, Perthamide F ......................... 82
4.3.4 Perthamide G ............................................................................... 84
4.3.5 Perthamides H and I ................................................................... 86
4.3.6 Perthamides J and K ................................................................... 87
4.3.7 Pharmacological activity of Perthamide C .............................. 89
4.4 Solomonamides ................................................................................... 94
4.4.1 Solomonamide A ........................................................................ 94
4.4.2 Solomonamide B .......................................................................... 99
4.4.3 Pharmacological activity of Solomonamide A ..................... 100
4.5 Macrolides from Theonella swinhoei ............................................. 103

CHAPTER 5
PLANTS AS PHARMACY ................................................................... 107

CHAPTER 6
CUCUMIS MELO ................................................................................. 109
6.1 Extraction and isolation ................................................................... 111
6.2 Structural characterization of Compound 20 ................................. 111
6.3 Structural characterization of Compound 21 ................................. 114
6.4 Other metabolites isolated ............................................................... 115
Index
CHAPTER 7
BORRAGO OFFICINALIS ................................................................. 107
7.1 Extraction and isolation ................................................................... 120
7.2 Structural elucidation of Compound 24 ......................................... 120

CHAPTER 8
RUSCUS ACULEATUS ....................................................................... 125
8.1 Extraction and isolation ................................................................... 127
8.2 Saponins ............................................................................................. 127
8.3 Structural characterization of Compound 25 ................................. 128
8.4 Structural characterization of Compound 26 ................................ 132
8.5 Structural characterization of Compound 27 ................................ 134

CONCLUSIONS ............................................................................................ 139

EXPERIMENTAL SECTION
I. General experimental procedures .................................................... 141
II. Experimental section of Coscinoderma mathewsi ........................ 142
III. Experimental section of Theonella swinhoei ................................ 151
IV. Experimental section of Cucumis melo ......................................... 190
V. Experimental section of Borrago officinalis ................................. 195
VI. Experimental section of Ruscus aculeatus .................................... 198

REFERENCES .............................................................................................. 209

ACKNOWLEDGEMENTS ........................................................................ 227

Abstract
ABSTRACT

Natural products have long been a source of bioactive metabolites utilized for the
treatment of human disease. In spite the impressive progress of new competing
methodologies, as for example, combinatorial chemistry and high-throughput
screening or genetic engineering, natural products remain a valuable source of
bioactive compounds with therapeutic potential.
In recent years, the marine environment has been seen as a vast resource for the
discovery of structurally unique bioactive secondary metabolites, some belonging
to totally novel chemical classes. In particular the Porifera have developed an
arsenal of new compounds.
Part of my research work is collocated within this area and concerns the
investigation of the natural products deriving from marine sponges. In the frame
of the project C.R.I.S.P. (Coral Reef Initiative of South Pacific), directed to the
chemical investigation and valorisation of the marine invertebrates of South
Pacific, particular attention was paid to two sponges: Theonella swinhoei and
Coscinoderma mathewsi.
From these sponges, several structurally interesting bioactive molecules have been
isolated with promising biological activities. Worthy of note are perthamides, a
family of cyclic octapeptides, encompassing majority of non-proteogenic amino
acids, and solomonamides which represent a new class of cyclic peptides,
featuring a potent in vivo anti-inflammatory activity. Solomonsterols have been
demonstrated the first examples of sulfated sterols with a truncated side chain
from a marine source endowed with a PXR agonistic activity.
I
Abstract
The structure elucidation of these new molecules was performed using the most
modern sophisticated spectroscopic techniques (2D-NMR and MS).
The main interest in these compounds is related to their strong biological activity,
that had led to pharmacological investigations on biomolecular target, the
mechanism of action and the pharmacophore useful in the identification of new
leads for developing a new generation of drugs. The detailed pharmacological
investigation has in some cases required the access to adeguate amount of natural
products or of semisynthetic derivatives through chemical synthesis, an issue
addressed in a research parallel to the present work.
The stereochemical novelty and complexity of some amino acid units of
cyclopeptides have required a tailored integrated approach which combined NMR
methods, stereoselective synthesis and LC/MS
The second part of my research has been employed and addressed on the analysis
of plants of Mediterranean area and used as foodstuff and as drugs in the folk
medicine, to isolate the active principles with biological activity and nutraceutical
property. In this respect, my research objectives have been to identify the
chemical constituents from three plants Cucumis melo, Borrago officialis and
Ruscus aculeatus.
It is clear that Nature continues to be a major source not only of potential
chemotherapeutic agents but also of lead compounds that have provided the basis
and inspiration for the semisynthesis or total synthesis of effective new drugs;
natural product chemistry has enriched both organic chemistry and medicine in a
myriad of different ways.

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