A group of medications long prescribed to treat tapeworm has inspired a compound that shows two-pronged effectiveness against COVID-19 in laboratory studies, according to a new publication appearing online in the journal ACS Infectious Disease.

The compound, part of a class of molecules called salicylanilides, was designed in the laboratory of Professor Kim Janda, Ph.D., the Ely R. Callaway, Jr. Professor of Chemistry and director of the Worm Institute for Research and Medicine at Scripps Research, in La Jolla, CA.

"It has been known for 10 or 15 years that salicylanilides work against certain viruses," Janda says. "However, they tend to be gut-restricted and can have toxicity issues."

Janda's compound overcomes both issues, in mouse and cell-based tests, acting as both an antiviral and an anti-inflammatory drug-like compound, with properties that auger well for its use in pill form.

Salicylanilides were first discovered in Germany in the 1950s and used to address worm infections in cattle. Versions including the drug niclosamide are used in animals and humans today to treat tapeworm. They have also been studied for anti-cancer and antimicrobial properties.

The modified salicylanilide compound that Janda created was one of about 60 that he built years ago for another project. When the SARS-CoV-2 virus became a global pandemic in early 2020, knowing that they may have antiviral properties, he started screening his old collection, first in cells with collaborators from Sorrento Therapeutics and The University of Texas Medical Branch, and later, after seeing promising results, working with Scripps Research immunologist John Teijaro, Ph.D., who conducted rodent studies.

One compound stood out. Dubbed simply "No. 11," it differs from the commercial tapeworm medicines in key ways, including its ability to pass beyond the gut and be absorbed into the bloodstream—and without the worrisome toxicity.