Researchers find antiviral compounds in common herbs.
Ethan Young-Hyun Lee (left) and Fangxiang Dong holding the herbs they are investigating for their antiviral properties.
Image Credit: Kimbra Cutlip
What if spices held the keys to fighting infection? Imagine a food or a drink or a dietary supplement made from allspice or parsley that blocked pathogens like the coronavirus from attacking your cells. Due to scientific advancement, that just may be possible one day.
Two graduate students in Liangli (Lucy) Yu’s research laboratory in the Department of Nutrition and Food Science are investigating the disease-blocking powers of common spices at the molecular level.
“We know that many medicinal compounds come from plants—take aspirin, for instance, which is derived from tree bark,” said master’s student Ethan Young-Hyun Lee. “There are so many spices out there that have been used in traditional remedies, but there’s not a lot of work on the anti-viral properties or the active compounds, especially at the molecular level.”
Lee and PhD student Fangxiang Dong are finding that compounds in the extracts of both parsley and allspice bind to ACE-2 receptors—those are the enzymes on the outside of human cells that the SARS-CoV-2 virus spike protein binds to. That’s how the virus gets into cells and causes COVID-19.
When these spice extracts bind to the ACE-2 receptor, it appears to block other molecules like the spike protein from binding. That would effectively reduce the ability of SARS-CoV-2 to infect a cell.
“These are really common herbs,” Dong said, “We know the extracts work in our lab, so when we identify the active compounds, it should be possible to make a functional food that is very accessible for people all over the world to take for helping prevent COVID.”
It would be tempting to think this means eating lots of parsley and allspice could prevent a COVID infection, but that would be taking things too far. The researchers said the amount of spice one would need to consume might be impractical if not impossible. Additional research is needed to confirm the effectiveness of herbal extracts and determine the dose level for human use.
But compared to synthesizing medicines, extracting compounds from herbs and spices is a relatively simple process that, if scalable, could provide a low-tech means of creating an effective vitamin-like supplement to inhibit viral infection.
This simple method involves mixing the spice with either water or a solvent, like ethanol, then draining off the liquid, which now contains the spice extract.
Dong found that both water-soluble and ethanol-soluble extracts of allspice were 100% effective at binding to the ACE-2 enzyme. As far as preventing the spike protein from binding, water-extract was 80% effective, and the ethanol soluble extract was 40% effective. The difference could be a matter of how or where the compounds in each extract bind to ACE-2 compared to where the spike protein binds.
That’s why the researchers said a combination of compounds from different extracts may be the key to finding the most effective formula for blocking the SARS-CoV-2 spike protein.
Lee looked at parsley extract and found that it bound to 86% of the ACE-2 in their experimental samples, and reduced spike protein binding by 70%.
The team’s next step is to determine exactly what compounds in their extracts are binding to the ACE-2 enzyme. That’s a bit more high tech, and uses a technique called liquid chromatography mass spectroscopy to identify every molecular compound in their spice extracts. So far, Dong has identified 10 compounds that had not been reported in allspice. Now he is working to isolate each compound, test its ability to bind to ACE-2, and understand how it works both alone and when combined with other compounds.
The researchers have a lot of work to do, but they are excited about the potential of spices beyond parsley and allspice to provide a similar immune boost for a variety of microbial infections. Other coronaviruses bind to cells using a spike protein, so it makes sense to look for herbs that can block them. And similar studies could identify the compounds that give many herbs their anti-inflammatory and antioxidant properties, leading to potential approaches to reducing the risk of inflammatory diseases.
