Hundreds of clinical trials are being conducted all over the world to find a vaccine for the disease and to find effective compounds that can help prevent COVID-19 . However, some experts indicate that even when the prophylactic drugs are available, these have some potential side effects that may affect a huge part of the population.
Now, a study conducted by a group of researchers from China and the USA suggests that some natural products and herbal medicines may be effective in preventing SARS-CoV-2 infection.
The study, published in the journal Frontiers in Pharmacology, indicates that natural products have tolerable toxicity and are hence considered to be excellent prophylactic agents.
The researchers summarised natural products that have been proposed as prophylactic agents against COVID-19 and herbal medications that are used for the treatment of respiratory distress syndrome in the study.
The researchers found some of the following drug targets and natural products that could act on them:
- Heat shock protein A5 (HSPA5): HSPA5 is a heat shock protein that the spike protein of SARS-CoV-2 recognises and uses to drive the infection process. The study indicates that phytoestrogens (plant-based estrogens) including daidzin, formononetin, and genistein) can bind with HSPA5 and keep SARS-CoV-2 from binding to the host cell.
- Transmembrane protease serine 2 (TMPRSS2): This is a host enzyme that plays an important role in viral entry into healthy cells. Inhibiting this enzyme from functioning will aid in preventing the virus from binding to ACE2 and hence preventing viral entry into host cells. Molecular docking studies have shown that Withania somnifera (also known as ashwagandha) can do just that along with reducing the expression of TMPRSS2 in certain cells.
- Papain like protease (PL pro) of SARS-CoV-2: PL pro is an enzyme that breaks down some SARS-CoV-2 polyproteins, which help in replication and survival of the virus. It has been indicated that certain compounds present in ginger and galangal can strongly bind with PL pro and may inhibit its function.
- RNA-dependent RNA polymerase (RdRp): This is an enzyme that catalyzes the formation of viral RNA once SARS-CoV-2 is inside the host cell. Studies have shown that compounds like quercetin (found in grapes, broccoli and cherries) and gallic acid (present in mango, tea, wine, and strawberry) can suppress the activity of this enzyme.
It is important to note that all these compounds are still in the initial stages of research and more studies are needed to confirm the findings and assess dosage and tolerability in various age groups.
The study suggested that several commercially available herbal medications are already being used as prophylactic agents against respiratory distress occurring due to flu and common cold.
Several studies have shown the efficacy of flavonoid-rich herbs against viruses in human lung cell lines. In a study done in China, herbs including liquorice root, Pinellia rhizome, and bitter apricot seed were indicated to be the most frequently prescribed for COVID-19 . The study also suggested that these medications were able to slow down the progression of the disease, reduce hospitalisation time, and help alleviate fever, cough and other symptoms associated with the disease.
For more information, read our article on AYUSH ministry advice for self-care during COVID-19 crisis.
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