Potential medicinal plant remedies and their possible mechanisms against COVID-19: A review

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) outbreak was first reported in Wuhan, a city in Hubei Province of China in December, 2019 and is known to be responsible for the novel coronavirus disease (COVID-19). COVID-19 was declared a pandemic in March, 2020 and since then, it has caused a number of deaths in over 200 countries around the world. Extensive researches have continued in the search of effective vaccines or drug compounds against SARS-CoV-2 and a total of 64 vaccines are currently in clinical trials with 12 currently approved for use by different regulatory bodies, depending on the country. Since the outbreak of SARS-CoV-2, many countries have utilised traditional herbal medicines alongside conventional drugs for the treatment of infected patients. In this review, traditional medicines used to prevent or treat SARS-CoV-2 infection are listed along with the plant parts as used by the traditional healers. Additionally, the possible mechanisms responsible for this preventive or therapeutic outcome are also identified and listed. Our literature search was conducted using Google Scholar, PubMed, Scopus and WHO website. Unpublished reports such asdissertations and theses are not included. Plant parts including roots, leaves, flowers, seeds and so on have been used in the treatment of COVID-19. These traditional medicinal herbs may exert their anti-COVID-19 activity by direct inhibition of the virus replication or entry. Some may act by blocking the ACE-2 receptor, SARS-CoV helicase, Type II Transmembrane Serine Protease (TMPRSS2) and which are required by SARS-CoV-2 in order to infect human cells. Others act by inhibiting the SARSCoV-2 life-cycle related proteins, namely chymotrypsin-like cysteine protease (3CL-pro) and Papain-like protease (PL-pro). Medicinal plants are promising alternative medicines for the treatment or prevention of SARS-CoV-2 infection. Further researches, are needed to decipher their active components and structures which may suggest clues for the development of drugs against this novel coronavirus. Keywords: Severe Acute Respiratory Syndrome (SARS-CoV-2), COVID-19, medicinal plants, plant parts, mechanism of action, pandemic,