Rosemary is a plant with medicinal properties highly appreciated for its uses in the kitchen or in aromatherapy, among others, which could also be used to combat coronavirus infection and other infectious diseases, since a new study has found carnosic acid, a compound of this herb is capable of blocking the interaction between the SARS-CoV-2 spike protein and the ACE2 enzyme, a receptor present in human cells that the virus uses to enter them.
The research that has discovered it has been co-directed by scientists from the Scripps Research Institute (La Jolla, California, United States) and has been published in the journal Antioxidants. The researchers presented evidence for their finding and reviewed evidence from previous studies suggesting that carnosic acid itself has an effect in inhibiting a powerful inflammatory pathway, which is active in severe cases of COVID-19, as well as in other pathologies, including Alzheimer’s disease.
“We believe 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,” said lead author Dr. Stuart Lipton. of the study and Professor and Chair of the Step Family Foundation in the Department of Molecular Medicine and founding co-director of the Center for Novel Neurodegeneration Drugs at Scripps Research.
Antiviral and anti-inflammatory potential of carnosic acid
In 2016, Lipton and his team demonstrated that carnosic acid activates the Nrf2 pathway, which regulates the expression of genes that protect cells from damage caused by free radicals and favors the production of antioxidant and anti-inflammatory proteins and enzymes, and found evidence of that decreases Alzheimer’s symptoms in mouse models of the disease, which are known to exhibit brain inflammation.
Carnosic acid modifies the ACE2 receptor for SARS-CoV-2, making it impregnable to the virus and thus blocking infection
The authors of the new research described their additional studies of this anti-inflammatory effect on immune cells that trigger inflammation in COVID-19 and Alzheimer’s, and also reviewed the results of studies by other scientists that suggest carnosic acid inhibits the inflammation in other disease models. They hypothesized that this effect could be beneficial in combating the inflammation that occurs in COVID-19 and in some cases of post-COVID syndrome or persistent COVID, symptoms of which include cognitive difficulties, which patients often define as “fog.” cerebral”.
The researchers also described a COVID-19 infection-blocking experiment conducted by Dr. Chang-ki Oh, a researcher in the Lipton lab, which using a standard infectivity assay showed that carnosic acid can directly block the ability of SARS -CoV-2 to infect cells, and that its infection-blocking activity increases progressively at higher doses.
Although the results of the study are preliminary, the researchers attribute this antiviral effect to carnosic acid, because despite being a safe and relatively unreactive compound, it is converted into its active form due to the inflammation and oxidation found in the sites of infection. These experts suggest that in this active form the compound modifies the ACE2 receptor for SARS-CoV-2, making it impregnable for the virus and, therefore, blocking the infection.
“Carnosic acid represents a ‘pathologically activated therapeutic agent’ in preclinical models of disease: inactive and harmless in its normal state, but converted to an active form where it needs to be active,” said Lipton, who with his colleagues is now working with Scripps Research chemists to synthesize and test more potent carnosic acid derivatives with optimized pharmacological characteristics for potential use in inflammation-related disorders.
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