From the Spice Cabinet to the Medicine Cabinet?

Instead of just livening up a crab boil, making salsa sing (and sting) or giving savory depth to curries, what if herbs and spices could give your health a kick, too? For instance, imagine a food, drink or dietary supplement made from allspice or parsley that blocked pathogens like the coronavirus from attacking your cells. University of Maryland research may someday make that possible.

Two graduate students in the Department of Nutrition and Food Science are investigating the infection-fighting powers of common spices.

“We know that many medicinal compounds come from plants. Take aspirin, for instance, which is derived from tree bark,” said Ethan Young-Hyun Lee ’22. “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 Fangxiang Dong, who both work in Distinguished University Professor Liangli “Lucy” Yu’s laboratory, are finding that compounds in the extracts of parsley and allspice bind to ACE-2 receptors. These are the enzymes on the outside of human cells that the SARS-CoV-2 virus spike protein binds to, allowing the virus to invade cells and cause COVID-19.

But when these spice extracts bind to the ACE-2 receptor first, it appears to block other molecules like the spike protein, which means it could 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 that eating lots of parsley and allspice could prevent a COVID infection, but that’s taking things too far. The amount of spice one would need to consume might be impractical if not impossible, the researchers said. 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.

The 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- and ethanol-soluble extracts of allspice were 100% effective at binding to the ACE-2 enzyme. The water-extract was 80% effective at preventing the spike protein from attaching to cells, and the ethanol soluble extract was 40% effective. Meanwhile, Lee found the parsley extract bound to 86% of the ACE-2 in their experimental samples, and foiled the spike protein 70% of the time.

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, the researchers said.

The team’s next step is to determine exactly what compounds in their extracts are binding to the ACE-2 enzyme using 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’s working to isolate each one, test its ability to bind to ACE-2, and understand how it works both alone and combined with other compounds.

The researchers are excited about the potential of spices beyond parsley and allspice to provide a similar immune boost for a variety of microbial infections. And similar studies could identify the compounds that give many herbs their anti-inflammatory and antioxidant properties, leading to potential treatments for inflammatory diseases.