On Sept. 4, the U.S. Food and Drug Administration (FDA) rejected an application to market Oleandrin as a dietary supplement, weeks after MyPillow CEO Mike Lindell promoted the extract as a potential treatment for the coronavirus to President Donald Trump and White House officials, according to Forbes. The FDA concluded that Oleandrin cannot legally be considered a dietary supplement because the extract has already been considered for use in a prescription drug, according to a recently released letter.

The agency added that even if Oleandrin was classified as a dietary supplement, Texas-based Phoenix Biotechnology Inc. did not provide sound evidence that it is safe.

“We also note that, even if  ‘Oleandrin’ was not excluded from the definition of dietary supplement, the agency has significant concerns about the evidence included in your submission as a basis for concluding that a dietary supplement containing ‘Oleandrin’ will reasonably be expected to be safe under the conditions of use described in your notification,” the FDA wrote.

Phoenix Biotechnology Inc. had applied for permission to market Oleandrin, an extract that comes from the Nerium oleander plant, as a dietary supplement ingredient. MyPillow CEO Mike Lindell—a major Trump supporter and donor—sits on the board of Phoenix Biotechnology and has also been promoting Oleandrin as a potential treatment for the coronavirus to Trump and senior administration officials, despite having no medical background or training.

There is no peer-reviewed evidence that Oleandrin is effective against the coronavirus in humans, and the U.S. Army Institute of Infectious Diseases discontinued testing it as a therapeutic for the virus after results were “inconclusive.”