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

Abstract

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 Unpublished reports such asdissertations and theses are not included.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,

Increasing the planting density of Cryptolepis sanguinolenta (Lindl.) Schlt increased root biomass and cryptolepine yield

“…The 3.4 benefit-cost ratio obtained or ‘45 plants/bed’ after 18 months of cultivation implied the benefit of farmer-intensive cultivation outweighed the cost, such that for every GHC1.00 invested in the cultivation of C. sanguinolenta at 45 plants/bed (25,920 plants/acre) planting density, GHC3.4 is realizable in benefits. Similar findings were reported in Manihot esculenta [ 46 ] and Ipomoea batatas [ 47 ] where a benefit-cost ratio greater than 1 was recorded.…”

Role of ethno-phytomedicine knowledge in healthcare of COVID-19: advances in traditional phytomedicine perspective

“…Ethno-phytomedicines or traditional medicinal plants are promising for the alternative management of SARS-CoV-2 as they can block and bind to ACE2 receptors, SARS-CoV helicase, and TMPRSS2 as well as inhibit SARS-CoV-2 entry and replication, reviewed by Ugwah-Oguejiofor and Adebisi [ 109 ]. Phytochemicals in medicinal plants have also been demonstrated to exhibit several mechanisms against coronaviruses by targeting virus entry inhibition, viral replication enzymes inhibition, and blockage of virus release activity as well as inhibition of SARS-CoV-2 spike protein, PL pro , and 3CL pro [ 65 , 72 ].…”

“…The active binding sites of SARS-CoV-2 that can be potential drug targets are chymotrypsin-like protease, RNA-dependent RNA polymerase, hemagglutinin esterase, papain-like protease, 2′-O-methyltransferase, helicase, spike receptorbinding domain, ACE2 receptor, and glucose-regulated proteins [73]. Ethno-phytomedicines or traditional medicinal plants are promising for the alternative management of SARS-CoV-2 as they can block and bind to ACE2 receptors, SARS-CoV helicase, and TMPRSS2 as well as inhibit SARS-CoV-2 entry and replication, reviewed by Ugwah-Oguejiofor and Adebisi [109]. Phytochemicals in medicinal plants have also been demonstrated to exhibit several mechanisms against coronaviruses by targeting virus entry inhibition, viral replication enzymes inhibition, and blockage of virus release activity as well as inhibition of SARS-CoV-2 spike protein, PL pro , and 3CL pro [65,72].…”

Chemical constituents from Limonium tubiflorum and their in silico evaluation as potential antiviral agents against SARS-CoV-2

“…10,11 In terms of its biological activity, family Plumbaginaceae has been reported to have medicinal plants with immunomodulatory activities. 12 Researches on species of this genus revealed important bioactivities, including antimicrobial, antioxidant, anti-inammatory and anticancer properties, with phenolics (epigallocatechin gallate, gallic acid, trans 3-hydroxycinnamic acid, myricetin and isorhamnetin) and triterpenoids (mainly limonoids) being considered as the main actives. 11 Other important pharmacological effects of Limonium species include the antiviral effect against herpes simplex type 1, HSV-1 and inuenza viruses.…”