“We have developed a green, time-, and cost-effective process that provides a simple route from natural products to lead compounds for drug discovery.”
Modifying natural products and screening them for potential pharmaceuticals can be difficult, expensive, and time-consuming. A group of European researchers has invented a new, quick, and environmentally friendly synthesis and screening method using an NMR-tube bioreactor.
Small modifications to natural compounds can result in potent pharmaceutical molecules. However, the complex nature of some natural molecules means that modifying them can require protecting a variety of functional groups, resulting in complex chemical procedures. As a result, synthesizing new natural derivates and identifying which of them may be potential drug compounds is a timely and expensive process.
Enzymes can conduct a wide variety of modifications on substrate molecules without the need for functional group protection, providing high selectivity, specificity, and efficiency.
Furthermore, enzymatic processes are often very environmentally friendly, with minimal waste products and low energy consumption compared with traditional chemical procedures. Exploiting enzymes to make new molecules could, therefore, revolutionize the drug discovery process.
A team of researchers from Greece and Italy recently devised a way to screen natural compounds to find out if they can be modified enzymatically and if the resulting product has potential as a new drug molecule.3
Their method used a nuclear magnetic resonance (NMR) tube as a bioreactor in a three-step process. Firstly, they introduced a library of natural products and a transformative enzyme to an NMR tube.
Saturation Transfer Difference (STD) 1D NMR was performed to identify which natural products bound with the transformative enzyme. Other components required for the reaction were not added to the solution at this stage, preventing the reaction from proceeding and enabling the detection of an enzyme-substrate complex.
Once a potential substrate was identified, it was added to a clean NMR-tube with the other reagents required for the enzymatic transformation and an immobilized version of the transformative enzyme. In-situ 2D 1H-13C HSQC NMR was used to monitor the reaction progress in real-time.
Once the reaction was complete, the target protein was introduced to the same NMR-tube, and STD 1D NMR was used to determine if the naturally-derived product molecule interacted with the protein. All NMR experiments were conducted on a Bruker AV-500 spectrometer equipped with a TXI cryoprobe.
The researchers later used the same methodology to produce new molecules from naturally occurring flavonoids and find out if any of them interacted with alpha-synuclein, a protein that has been linked to the development of Parkinson’s disease and other neurodegenerative diseases.
The team was successfully able to produce a substrate that bound with alpha-synuclein, marking it as a potentially attractive candidate for drug development.
Until now, modifying and screening natural products has been a complicated, expensive, and time-consuming part of the drug discovery pipeline. This new method using enzymes and an NMR bioreactor is simple, inexpensive, environmentally friendly, and quick compared to the chemical procedures traditionally used.
The technique could be applied to a range of other natural products, enzymatic transformations, and target proteins, to produce a myriad of new potential therapies.
Chatzikonstantinou, A. V., et al. Enriching the biological space of natural products and charting drug metabolites, through real-time biotransformation monitoring: The NMR tube bioreactor. BBA – General Subjects, 2018. DOI: 10.1016/j.bbagen.2017.09.021.