Natural ingredients for chemical synthesis

Pharmaceutical, chemical and cosmetics companies traditionally make chemical ingredients for their products using expensive, precious metal-containing catalysts (which speed up reactions) or hazardous organic solvents. For the EU-funded AQUACAT (Tailor made lipases for synthetic catalysis in biphasic media: From poly (lactone) applications towards novel sugar esters) initiative, researchers attempted to develop a greener chemical production process inspired by nature.

AQUACAT combined physical chemistry, polymer science and enzyme technology to convert a natural enzyme that breaks down fats in the body into an industrial catalyst. Researchers were particularly interested in using this enzyme, called lipase, to manufacture two products with numerous important applications in the food, medical and cosmetics industries.

The first product, polylactone nanoparticles, can be used as miniscule drug delivery vehicles to carry drugs to specific cells in the body. The second product, a sugar ester, contains water-soluble sucrose and oil-soluble lipids that serve as non-toxic emulsifiers for food and cosmetics. Sugar esters can also be used as heat-stable, low-calorie fat substitutes for food products.

To make sugar esters, sucrose needs to be chemically manipulated to resemble triacylglycerols, the main constituent of both animal and plant fat. Researchers tried various ways to do this using lipase as a catalyst to join lipid-containing molecules with sucrose in an oil-and-water emulsion.

First, they used a lipase enzyme from the yeast Candida rugose. This however, would only convert part of the sucrose molecule to a sugar ester.

They then tried a cocktail of commercially available lipases from different fungal species, but none of them was active in AQUACAT's biphasic system. Despite these hurdles, a high-purity sugar ester produced during the project can be used as a surfactant in products like detergents, emulsifiers and foaming agents.

In principle, AQUACAT's lipase-catalysed process may be used to produce myriad chemicals in a sustainable and green way, benefiting both industry and society.