Evidence of the Existence of a Large Amount of Cationic Antimicrobial Peptides in Propolis, with a Strong Physical/Electrostatic Mechanism of Action (Detergent-like), and their Possible Promising Effects in the Treatment of COVID-19 by means of Propolis Extract Inhalation
For more than a century, despite numerous documented therapeutic effects, extraction, administration and studies on propolis have all been focusing mostly on its phenolic compounds. However, some important components may have gone unnoticed and this perhaps has been preventing the exploitation of the full efficacy of the substance in the treatment of human infections/diseases. In the scientific literature there are already consistent clues that propolis main components, responsible for its medicinal properties, are, actually, antimicrobial peptides (AMPs). To investigate this possible existence of AMPs in propolis, experiments that can be easily reproduced were developed and, beyond not allowing the rejection of the hypothesis, may have revealed extraordinary evidence that the substance has a large amount of cationic AMPs, which produce strong effects. It was found that propolis, differently from the effects produced only by its phenolic compounds, has, given the significant hydrophobic residues of the water-soluble cationic peptides that abound in it, strong amphipathic/surfactant (detergent-like) character and its therapeutic mechanism of action is physical/structural, through electrostatic force. In order to produce effects, the cationic peptides in propolis bind, by attraction, to anionic moieties of the organism/agent with which the substance interacts, and generate a cascade of phenomena. Thus, the results of the experiments developed suggest that there is a potential that should be extensively explored by science; i.e., propolis and its cationic AMPs possibly have strong antimicrobial and disease fighting properties and are designed to not be resisted by any pathogen, mainly if applied directly to the infection/disease site in the necessary amount. The experiments may also have revealed, as studies have been demonstrating that propolis is non-toxic and safe to be used by humans even in large doses, a possible powerful therapeutic agent that is ready to be utilized now against SARS-CoV-2. Propolis existing extracts may be easily tested for effectiveness and their use for prophylaxis or treatment of COVID-19 may be quite simple given that the substance, as demonstrated, seems to be basically a more complex and selective/non-toxic “detergent/soap” that humans have been safely using internally. Inhalation of extracts may be highly effective and the best existing way for propolis parenteral administration, enhancing the absorption and systemic effects; it may also allow direct action against SARS-CoV-2 in the respiratory tract – possible prompt binding of the positively charged AMPs from propolis to all negatively charged parts of the viruses/host’s cells and their products/substances, potentially annihilating the virus and producing immunomodulatory effects. In conclusion, propolis may be able to bring together, in the same substance, the expected effects of various therapeutic agents, and, as a result, it is possibly a viable and promising treatment alternative for COVID-19, especially in comparison with the traditional drugs being tested at the moment. Through the present study it was demonstrated as well that propolis has sufficient preclinical proof and safety to be tested in humans; therefore, considering the current pandemic, it is suggested that further studies on the substance should start urgently, primarily clinical trials on its possible efficacy in the treatment of COVID-19.