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