Transcript Cyclodextrins - An Overview

Gent 2001
Cyclodextrins
An Overview
Matthias Arenskötter
Florence Folmer
Chris Llewellyn
Aurélie Pardo
Frank Reinecke
Grazia Trebbi
Cyclodextrins - An Overview
1. Introduction
2. Microbial Production
3. Purification And Fractionation
4. Properties
5. Applications
Introduction
• Cyclodextrins (CDs) are torus shaped cyclic
oligomers consisting of 6 (),7 (b) or 8 (g-CD)
glucose units with -1,4-linkages with a
hydrophobic cavity and a hydrophilic exterior
O
CH2OH
O
OH
CH OH
O 2
HO
HO
O
OH
O
O
OH
OH
CH2OH
CH2OH
OH
HO
O
O
HO
O
OH
OH
CH2OH O
HO
CH2OH
O
O
Introduction
History:
• 1891 Discovery, Villiers
• 1903 Descriptions of properties,
Shardinger
• 1939 Tilden and Hudson were able to
show that the conversion of starch to CD
was due to the action of an enzyme, CD
Glycosyl-Transferase (CGTase), which
was secreted into the culture medium.
Introduction
• 1957 Complexation ability of CDs widely
accepted; Cramer, French
• 1981 First International Symposium on
CDs, Szejtli
• 1987 Total synthesis, Ogawa
• 1994 Total synthesis of
cyclo[D-Glcp(1->4)]5
Introduction
• Today CDs are only synthesized either by
fermentation or enzymatically.
• Many CGTases from different
microorganisms are known, cloned,
sequenced, characterized and used for
production of CDs.
Introduction
Applications:
• Because of their unique properties CDs
allow „packaging on a molecular level“ of
various molecules which is applied in
pharmaceutics, food and flavours etc...
• Used in chromatographic columns CDs can
separate stereoisomers.
• Derivatives of CDs can even be used to
mimic enzymes.
Cyclodextrins - An Overview
1. Introduction
2. Microbial Production
3. Purification And Fractionation
4. Properties
5. Applications
Microbial Production
• CGTases are produced by many different
bacterial species of the genus Bacillus but
also by Flavobacterium sp., Klebsiella
pneumoniae and Micrococcus sp.
• Genes have been cloned and recombinantly
expressed in Escherichia coli and other
organisms, including for example Solanum
tuberosum (Potato).
Microbial Production
• The CGTase acts on linear starch and
transfers a part of the chain (F) to its own
non-reducing end (A) as indicated in this
model:
E
G
F
D
H
A
C
B
starch
E
D
CGTase
G
F
A
C
B
-CD
H
Cyclodextrins - An Overview
1. Introduction
2. Microbial Production
3. Purification And Fractionation
4. Properties
5. Applications
Purification and Fractionation
• Enzymatic synthesized CDs are selectively
precipitated by organic solvents.
-CD
b-CD
g-CD
precipitating agent
1-decanol
toluene
cyclohexadec-8-en-1-ol
yield (%)
40
50-60
40-50
Cyclodextrins - An Overview
1. Introduction
2. Microbial Production
3. Purification And Fractionation
4. Properties
5. Applications
Properties
Important Properties:
• CDs have hydrophobic cavities of different
sizes enabling the complexation of
hydrophic guest molecules.
• These complexes represent a solution for
insolubility.
• They have neither a reducing nor a nonreducing end-group.
Properties
Stability:
• CDs are not decomposed by hot aqueous
alkali and rather resistant to acid hydrolysis.
• CDs are resistant to -amylases (except
microbial enzymes) and they are completely
resistant to yeast-fermentation and
b-amylases.
Properties
Properties
Molecular weight
Glucose monomers
Internal cavity diameter
(angstroms)
Water solubility
(g/100mL: 25 deg. C)
Melting range (deg. C)
Water of crystallization
Water molecules in cavity
Cavity volume (ml/mol)
Price (US$/g pharma-grade)

b
g
972
6
4.7-5.3
1135
7
6.0–6.6
1297
8
7.5–8.3
14.2
1.85
23.2
255-260
10.2
6
174
1.0
255-265
13-15
11
262
0.025
240-245
8-18
17
472
0.8
Cyclodextrins - An Overview
1. Introduction
2. Microbial Production
3. Purification And Fractionation
4. Properties
5. Applications
Applications
Pharmaceutical industry:
• Treatment of inflammation or throat
infection (with iodine)
• Coronary dilatation (with nitroglycerin)
• Anti-ulcerate (with benexate)
• Vectors for vitamins or hormones
• Reduction of side-effects and increase in
efficiency of anti-cancer drugs
Applications
Solid
Complex
Cyclodextrin
Pharmaceutical
Dissolution
(k )
industry:
Competing
Agent
d
(kc)
Dissolved
Complex
(ki)
Adsorption
(ka)
Drug
Competing AgentCycloddextrin Complex
Biomembrane
Systemic Circulation
Drug
Applications
Cosmetics & Hygiene:
• Long-lasting perfume release
• Deodoriser (with peppermint oil, i.e.)
• Removal of dryness wrinkles (with seaweed
compounds, Vitamin A & E)
• Anti-cellulitis compound
• Shampoo industry
• Teeth cleaning, anti-plaque compound
• Antibacterial in refrigerators
Applications
Food industry:
• Emulsion stabiliser
• Taste-masking
• Long-lasting flavouring
• Removal of cholesterol from milk, butter,
eggs, a.o.
Applications
Paint industry:
• Increase in compatibility of paint
ingredients
• Increase in stability of the paint
• Increase in the range of colours and in the
quality of dyes
Applications
Environmental protection:
• Reduction in oxidiser requirements in paper
production
• Environmentally friendly oil-spill clean-up
• Treatment of tree-wounds (with auxin)
• Mobilisation of toxins without leaving
toxic residues behind (innovative technique)
Applications
Environmental protection:
• Removal or detoxification of waste
material, esp. aromatic pollutants
• Use in agriculture to increase the stability
and the efficiency of herbicides,
insecticides, repellents,…
Applications
Chemical and biochemical applications:
• Reaction catalyst in adhesives
• Use in chromatography (separation of
stereoisomers)
• Increase in speed of diagnostic test reaction
Applications
Chemical and biochemical applications:
• Enzyme mimicry
S
S
N
3+
La
O O
P
O2N
O
N
O
O
NO2
O
Dimer of b-cyclodextrin linked on primary side by a
metal-binding-group as catalyst of hydrolysis of a
phosphate diester
Summary
• When Cyclodextrins were discovered they
were just a chemical curiosity but today a
lot of applications are known.
• Due to intensive studies and advances in
production procedures prices continue to
decrease making CDs attractive for many
applications.
• To date more than 3300 European Patents
are registered indicating great industrial
interest.
Group Members
• Matthias Arenskötter, Westfälische WilhelmsUniversität Münster, Germany
• Florence Folmer, University of Wales Bangor, UK
• Chris Llewellyn, University of Wales Swansea,
UK
• Aurélie Pardo, Institue Nationale Polytechnique de
Toulouse, France
• Frank Reinecke , Westfälische WilhelmsUniversität Münster, Germany
• Grazia Trebbi, Universita´ di Bologna, Italy