Smart chemistry and light irradiation at the right wavelengths are the secrets behind a new technology for making chemicals that are essential in many products, including food, medicine and perfume.
Many people have not heard of cyclodextrins and what they do, but these organic molecules are an important billion-dollar industry with applications in the food industry, personal care and the pharmaceutical industry.
Cyclodextrins are in high demand, and now an international group of researchers has developed a method to produce the most expensive type in an ingenious way using clever chemistry and light with a specific wavelength.
“This production method may lead to both cheaper and more environmentally sound production of a purer product that industry needs,” explains a researcher behind the new technology, Sophie R. Beeren, Associate Professor, Department of Chemistry, Technical University of Denmark, Kongens Lyngby.
The research results have been published in Chem.
One molecule is especially expensive to produce
Cyclodextrins are made from glucose building blocks assembled in a doughnut-like ring.
The natural cyclodextrins can contain six, seven or eight glucose units and are then referred to as alpha-, beta- or gamma-cyclodextrins.
Each cyclodextrin has different industrial applications, and they are currently used in more than 30 drugs. Cyclodextrins can hold drugs inside them. When they are consumed, they help transport the drug molecules throughout the body.
Gamma-cyclodextrin can shield drugs from external environments and stabilise them during storage. It also reduces the amount of active drug required per pill, making the pills cheaper to manufacture and reducing the risk of side-effects.
Manufacturing gamma-cyclodextrin is expensive
The researchers focused on gamma-cyclodextrin, the most difficult of the native cyclodextrins to produce.
Gamma-cyclodextrin is both difficult and expensive to manufacture because it is very water soluble and therefore difficult to isolate in industrial production.
Cyclodextrins can be produced on an industrial scale by using a template that the glucose building blocks surround. Enzymes connect the building blocks together to form the finished cyclodextrin.
However, removing the gamma-cyclodextrin template is very energy intensive, making the process more expensive.
Light induces the template to change shape
The researchers developed a completely new type of template so that the gamma-cyclodextrins can be removed much more easily.
The hydrazone photoswitch template they developed can be removed by light irradiation at a specific wavelength.
This means that the researchers can produce gamma-cyclodextrin using a glucose source, the photoswitch template and an enzyme. The gamma-cyclodextrin forms around two molecules of the template. Then the researchers irradiate the solution with 410-nm light, and the gamma-cyclodextrin is released from the templates and can be purified and used.
“The photoremovable template is the ideal size for making gamma-cyclodextrins and not the other cyclodextrins. The gamma-cyclodextrin falls off when you irradiate the template, making this proof-of-concept strategy a completely new way of producing these industrially attractive molecules,” says Sophie R. Beeren.
Adapted to produce other molecules
This is good news, considering the prices of the various cyclodextrins because gamma-cyclodextrin is by far the most expensive and costs many times more to produce than the other two.
However, Sophie R. Beeren explains that the technology is far from ready for the market.
“We still need to develop the concept further, but we have shown that we can use photoswitch templates to control dynamic enzymatic synthesis. There are exciting possibilities for producing cyclodextrins and many other molecules,” adds Sophie R. Beeren.
