Research Stories

A hotpot dinner inspired a group of chemists to synthesise the chemical that causes that tingling sensation. Its potential uses are numerous.

"Look at the everyday things around you. Question what you see, hear, taste, smell – that is how discoveries are made," says Dr Patrick Toy, Associate Professor, Department of Chemistry in the Faculty of Science. It was this kind of thinking that led him and his team to find a way to synthesise hydroxyl alpha sanshool (HAS), a chemical found in Sichuan peppercorns (huajiao) – the chemical that causes your lips and tongue to tingle and go slightly numb. The discovery has potential applications in pharmaceutical and cosmetic fields.

The idea of experimenting with peppercorns was born when Dr Toy and his research group were enjoying a Sichuan hotpot dinner and began discussing the tingling sensation you get when eating the hot peppercorns in the dish. “It’s not spicy, it’s bitter and it has a numbing, tingling sensation,” says Dr Toy. “As we enjoyed our hotpot we contemplated what caused that numbing sensation and how it could be usefully applied in research.”

The next day, Dr Toy looked it up on that seemingly unlikely spot for scientific discovery – Wikipedia. He found that the compound which causes the numbness was discovered 20 years but it is only in the past four or five years that people have begun studying how it works in detail. In recent years, interest has risen because of the potential applications for HAS and it has suddenly become a hot area of research.

"We found a means to make hydroxyl alpha sanshool that doesn’t require a lot of fancy technology or equipment or skills... and it can be done on an industrial scale."

Dr Patrick Toy

Dr Toy synthesised the HAS compound that is found naturally in Sichuan peppercorns 

The full version of this article was originally published in Bulletin. Please click here to view this HKU publication.