ABSTRACT
In the face of the COVID-19 pandemic, there is still a lack of miracle drugs for treatment. Repurposing drugs such as Remdesivir and corticosteroids to treat COVID-19 are being studied. Traditional Chinese medicine was widely used during the outbreak of Severe Acute Respiratory Syndrome (SARS) coronavirus infection in China in 2003. It was found that standard medical treatment combined with Chinese medicine treatment may improve the symptoms of SARS patients and speeding resolution of lung infiltration. The commonly used prescriptions for preventing the coronavirus infection are Sangjuyin plus Yupingfeng powder. Various Traditional Chinese medicines with potential to fight SARS-CoV-2 include Liquorice Root and Rhizome, Rhubarb, Heartleaf Houttuynia Herb, Indi-gowoad Root, Tangerine Peel, Scutellaria Root, and Red Sage Root and Rhizome etc. In addition, Chinese patent medicines including Shuanghuanglian Oral liquid, Lianhua Qingwen Capsule, Jinhua Qinggan Granule and Taiwan Chingguan Yihau are recognized as plausible agents for the treatment of novel coronavirus pneumonia. The antiviral, anti-inflammatory and immunomodulatory effects of selected Chinese herbal drugs may attribute to their inhibiting the binding of the coronavirus spike protein to the angiotensin-converting enzyme 2 (ACE2) receptor, inhibiting key enzymes such as 3-chymotrypsin-like protease and ribonucleic acid (RNA)- dependent RNA polymerase during viral replication, and reducing pro-inflammatory cytokines. Since most of the relevant studies mentioned the potential anti-SARS-CoV-2 activity of these agents were only in vitro and animal experiments, more randomized double-blind controlled trials are needed to provide reliable evidence of clinical efficacy in future.
ABSTRACT
Respiratory viral infections are a major public health concern because of their global occurrence, ease of spread and considerable morbidity and mortality. Medical treatments for viral respiratory diseases primarily involve providing relief from symptoms like pain and discomfort rather than treating the infection. Very few antiviral medications have been approved with restrictive usage, high cost, unwanted side effects and limited availability. Plants with their unique metabolite composition and high remedial values offer unique preventive and therapeutic efficacy in treatment of viral infections. The present review is focused on the types and mode of action of plant secondary metabolites that have been used successfully ί in the treatment of infections caused by respiratory viruses like Influenza, SARS, MERS, RSV etc. Plant metabolites such as phenolics, alkaloids, terpenoids and oligosaccharides inhibit attachment and entry of the virus. Others such as flavonoids, viz quercetin and baicalein, alkaloids viz sanguinarine, berberine and emetine, specific lipids and fatty acids prevent viral replication and protein synthesis. These metabolites have the potential to be used as lead molecules that can be optimized to develop potent drugs for effectively combating pandemics caused by respiratory viruses.