Cyclodextrins An Overview Matthias Arenskötter Florence Folmer Chris Llewellyn Aurélie Pardo Frank Reinecke Grazia Trebbi Gent 2001.

Cyclodextrins An Overview

Matthias ArenskötterFlorence Folmer

Chris Llewellyn Aurélie PardoFrank ReineckeGrazia Trebbi

Gent 2001

1. Introduction

2. Microbial Production

3. Purification And Fractionation

4. Properties

5. Applications

Cyclodextrins - An Overview

Introduction• Cyclodextrins (CDs) are torus shaped cyclic

oligomers consisting of 6 (),7 () or 8 (-CD) glucose units with -1,4-linkages with a hydrophobic cavity and a hydrophilic exterior

O

CH2OH

OOH

OHO

O

O

CH2OH

O

OH

OH

O

CH2OH

OH

OH

O

CH2OH

OH

OH O

O

CH2OH

O

OH

OH

O

CH2OH

OH

OH

IntroductionHistory:

• 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.

IntroductionApplications:

• 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.

1. Introduction

2. Microbial Production

3. Purification And Fractionation

4. Properties

5. Applications

Cyclodextrins - An Overview

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).

• 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:

Microbial Production

CGTaseA

BC

D

E F G H

starch

A

BC

D

E F G H

-CD

1. Introduction

2. Microbial Production

3. Purification And Fractionation

4. Properties

5. Applications

Cyclodextrins - An Overview

• Enzymatic synthesized CDs are selectively precipitated by organic solvents.

Purification and Fractionation

precipitating agent yield (%)-CD 1-decanol 40-CD toluene 50-60-CD cyclohexadec-8-en-1-ol 40-50

1. Introduction

2. Microbial Production

3. Purification And Fractionation

4. Properties

5. Applications

Cyclodextrins - An Overview

PropertiesImportant 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 non-reducing end-group.

PropertiesStability:

• 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 -amylases.

Properties

Properties

Molecular weight 972 1135 1297Glucose monomers 6 7 8Internal cavity diameter(angstroms)

4.7-5.3 6.0–6.6 7.5–8.3

Water solubility(g/100mL: 25 deg. C)

14.2 1.85 23.2

Melting range (deg. C) 255-260 255-265 240-245Water of crystallization 10.2 13-15 8-18Water molecules in cavity 6 11 17Cavity volume (ml/mol) 174 262 472Price (US$/g pharma-grade) 1.0 0.025 0.8

1. Introduction

2. Microbial Production

3. Purification And Fractionation

4. Properties

5. Applications

Cyclodextrins - An Overview

ApplicationsPharmaceutical 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

ApplicationsPharmaceutical

industry:

SolidComplex

Dissolution (kd)

Dissolved Complex

Adsorption (ka)

(kc)

CyclodextrinCompeting

Agent

Competing Agent-Cycloddextrin Complex

(ki)

Drug

Drug

Biomembrane

Systemic Circulation

ApplicationsCosmetics & 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

ApplicationsFood industry:

• Emulsion stabiliser

• Taste-masking

• Long-lasting flavouring

• Removal of cholesterol from milk, butter, eggs, a.o.

ApplicationsPaint 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

ApplicationsEnvironmental 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)

ApplicationsEnvironmental protection:• Removal or detoxification of waste material, esp.

aromatic pollutants• Use in agriculture to increase the stability and the

efficiency of herbicides, insecticides, repellents,…

ApplicationsChemical and biochemical applications:• Reaction catalyst in adhesives• Use in chromatography (separation of stereoisomers)• Increase in speed of diagnostic test reaction

ApplicationsChemical and biochemical applications:• Enzyme mimicry

Dimer of -cyclodextrin linked on primary side by a metal-binding-group as catalyst of hydrolysis of a phosphate diester

O2N

O

NO2

O

NN

S S

La

O

O

O

P

O

3+

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 Wilhelms-

Universität 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 Wilhelms-Universität Münster, Germany

• Grazia Trebbi, Universita´ di Bologna, Italy