Please no one take this to mean sprinkling herbs on your dinner is a substitute for getting vaccinated, but a compound in rosemary (Salvia rosmarinus) is being proposed for investigation as a COVID-19 treatment. Plenty of molecules have antiviral effects in the test tube that have inspired further research, usually without success, but carnosic acid is intriguing researchers because it has two entirely separate modes of operation that could prove useful against the same disease.
Carnosic acid, which makes up about 2 percent of rosemary's dry weight, was already under investigation before the pandemic hit for its anti-inflammatory effects on the brain. The herb itself, and its oil, have been used in traditional medicines at least since Roman times.
More recent research shows the NLRP3 inflammatory pathway carnosic acid disrupts is implicated in long-COVID, as well as Alzheimer's and Parkinson's disease. In a new paper in the journal Antioxidants, researchers at the Scripps Institute review this evidence, and also show there is another path by which carnosic acid could have anti-COVID-19 properties.
"We think that carnosic acid, or some optimized derivative, is worth investigating as a potentially cheap, safe, and effective treatment for COVID-19 and some other inflammation-related disorders," senior author Professor Stuart Lipton said in a statement.
Author Dr Chank-ki Oh found carnosic acid interferes with SARS-CoV-2's capacity to infect cells, which it is thought to do by preventing the virus's infamous spike protein from locking with ACE2 receptors on human cells. In cell cultures, Dr Oh found carnosic acid is almost 90 percent effective in blocking SARS-CoV-2 infection.
This is independent of the way carnosic acid and its derivative carnosol, also found in rosemary, inhibit NLRP3 inflammation. The paper reports NLRP3 has been linked both to the cytokine storms that pose a threat during acute COVID, and the “brain fog” and anxiety that are common in long-COVID.
Lipton described carnosic acid as showing signs of being a “Pathologically activated therapeutic...inactive and innocuous in its normal state, but converted to an active form when it needs to be active.”
An almost infinite array of chemicals either kill or block COVID-19 in test tubes, but most fail for one reason or another when transferred to living things. Success in vitro inspired the enthusiasm for hydroxychloroquine and Ivermectin being touted as COVID treatments, although we're not aware of any evidence urine kills viral cells, even in test tubes.
Carnosic acid could easily prove similarly disappointing, so the only reason to be adding rosemary to your meals is if you like the flavor, but the Scripps team hopes they have found what will eventually prove its worth. Carnosic acid is also found in rosemary's near-relative sage. Hopefully, its benefits will be proved in thyme.