Antimicrobial compound added to face masks

Scientists from Nanyang Technological University, Singapore (NTU Singapore) have developed a sustainable and green way to extract a high-quality antimicrobial compound from seeds — a compound with powerful antioxidants that enabled it to kill 99% of harmful bacteria in laboratory tests.

Typical antimicrobial solutions require the use of harsh chemicals such as solvents or use ions obtained from various metals such as silver. In contrast, NTU Professor William Chen and his team used ball-milling, known as solid-state synthesis, with clean water processes to extract the antimicrobial compounds from the discarded husks of seeds without the need for harsh chemicals — a far more sustainable process.

Researchers from Prof Chen’s team conducted lab experiments using the extracted antimicrobial liquid compound, testing it on common food pathogens Escherichia coli and Staphylcoccus aureus, which typically cause food poisoning when consumed. When in contact with bacteria, the compound binds to the bacteria wall, inactivating the protein and enzymes on the wall, thus inhibiting bacterial growth. In the tests, the compound was shown to be able to create a ‘zone of inhibition’ which neither S. aureus nor E. coli bacteria were able to penetrate.

The NTU research team was initially targeting to create a new generation of sustainable antimicrobial food packaging. But following discussions with global apparel and textiles manufacturer Ghim Li Group (GLG), the newly discovered compound found another important application — as a fabric finishing in the company’s re-usable masks, recently distributed to Singaporeans as part of the government’s strategy to fight the COVID-19 pandemic.

“As a leading research-intensive university, NTU is proud that our research efforts have yielded a valuable resource for Singapore in the fight against infectious diseases,” said NTU Senior Vice President (Research) Professor Lam Khin Yong. “This innovation was an unexpected result of research in food science being applied in re-usable masks used in the fight against COVID-19. This is a great example of how academia and industry can work together to create value for Singapore’s economy and help Singapore companies become more competitive.”

GLG is now looking to embark on a future research partnership with NTU to further research and develop innovative antimicrobial compounds and to identify future applications. As the natural compound is considered non-toxic for humans, it has huge potential to be applied in other types of products, such as personal protective equipment, sports apparel, paints and disinfectants.

One potential area of research could be to further study the properties of the antimicrobial compound and its effects on different bacteria and viruses. As noted in a 2005 study by Taipei’s National Health Research Institutes, similar compounds found in black and green teas (also found commonly in seeds) demonstrated inhibitory activity against a protease that was deemed critical to the viral replication of the severe acute respiratory syndrome coronavirus (SARS-CoV).

“Our new antimicrobial compound assigned to Ghim Li Group has been tested in our labs to be safe for humans and can be sustainably produced in large quantities using green processes,” Prof Chen concluded. “We hope to continue this productive partnership where we can develop sustainable innovations that will keep Singapore at the forefront of a circular economy.”

Image caption: Crushed seeds from which antimicrobial compounds can be extracted using green processes.

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