Medicinal Plants, Phytomedicines and Traditional Herbal Remedies for Drug Discovery and Development against COVID-19

Coronavirus disease-2019 (COVID-19) is a pandemic disease due to the infectious virus “Severe Acute Respiratory Syndrome-CoronaVirus-2 (SARS-CoV-2)”. Scientifically validated phytoconstituents sourced from “Mother Nature” are now an area of interest and targeted approach as a worldwide prophylactic measure against SARS-CoV-2. This section focuses on providing a clear understanding of the structure of SARS-CoV-2 as well as verified phytoconstituents from traditional medicine (TM) for addressing the virus with all feasible targets. Target-specific inflammatory pathways triggered by SARS post-infection include NLRP3, Metallopeptidase Domain 17, JAK-STAT, p38-MAPK, endocytosis pathways e.g. Clathrin, HMGB1 as well as associated interleukins and cytokines are primarily highlighted, which directly or indirectly trigger the immune system and play a significant role. Selected Indian medicinal herbs and their possible leads are detailed below, with the goal of focusing on specific routes with a high likelihood of preventing pandemics in the future.

COVID-19 has taken the global population by surprise. All around the globe, there have been combined efforts from scientists to find a cure for this disease. Numerous alternative modes of medicine have also been explored for the same. In this chapter, the authors have reviewed the role of medicinal plants and phytomedicine in combating this disease. There is an urgent need to standardise the protocols for conducting clinical experiments on herbal medication for COVID-19 to ensure consistency and batch-to-batch efficacy. Also, literature regarding these studies needs to be categorised and catalogued properly. The scientific community needs to draw from the rich diversity of herbal and medicinal plants to meet this extraordinary challenge. 

Nutritional measures and food components such as micronutrients, macronutrients, and food bioactive compounds, boost the immune system to effectively fight COVID-19. Nutrient deficiencies reduce immune functions against COVID-19, while supplementation of specific nutrients improves the immune system against viral disease. Several macronutrients and micronutrients, including bioactive compounds, prebiotics, and probiotics, have been linked to COVID-19 treatment and prevention. Vitamins D, C, A, E, and B vitamins have been linked with improvement and recovery from COVID-19. Several minerals such as zinc, selenium, iron, copper, magnesium, etc. have activities against SARS-CoV-2 and COVID-19. Many studies have shown that bioactive compounds such as resveratrol, astaxanthin, quercetin, docosahexaenoic acid, eicosapentaenoic acid, epigallocatechin-3-gallate, theaflavin, etc., have promising actions against SARS-CoV-2 and COVID-19. Foods and food components should be properly utilized to fight COVID-19 and are valuable in drug discovery against COVID-19.

The first and the most vital biotic response of the immune system against stress, oxidation, infection, injury and irritation is inflammation. Reports revealed that the anti-inflammatory effect is mediated by various inflammatory cytokines and non-cytokine mediators i.e. tumor necrosis factor alpha-a, nitric oxide, interleukins, interferon gamma-g, and prostaglandin E2 respectively. Herbal medicine is playing an important role in the treatment of COVID-19. Plant-based foods are rich source of bioactive compounds (phytochemicals) and have a potential anti-inflammatory effect. The purpose of this chapter is to sum up the recent findings of work already done both in vitro and in vivo on the anti-inflammatory effects of plant-based foods. As a source of natural modulators of gene expressions, phytochemicals from plants could be used along with other pharmaceutical formulations as anti-inflammatory drugs. Therefore, the regulation of inflammation by modulating the pro-inflammation and anti-inflammation cytokine expression through different plant-based food also boosts immunity. 

Pulmonary diseases have been increasing for decades, which are responsible for the high incidence of morbidity and mortality all over the world. Since the year 2019, the world suffers from coronavirus disease 2019 (COVID-19) which is caused by SARS-CoV-2 and it was classified as a pandemic respiratory disease by the World Health Organization (WHO). The problem of this virus is the lack of a medicine or a specific antivirus drug to combat it, so many approaches have been designed to protect the patients from its symptoms and side effect and also to raise the human innate immunity. Consequently, this chapter will provide an overview of herbs and their derived natural products which have anti-inflammatory, immunomodulatory, and anti-microbial activities which might be beneficial for the discovery of structurally-related compounds that can be candidate therapeutics alleviating the symptoms associated with acute respiratory diseases.

By the end of 2019, and by the year 2020, the COVID virus had spread, and in March 2020, the World Health Organization declared COVID 2019 an epidemic that invaded many Arab and foreign countries and claimed many lives. Since ancient times, medicinal plants have played an important role in treating many epidemic diseases. A Cochrane study confirmed that herbal plants have an effective role in treating respiratory epidemics such as SARS. In China, the National Health Committee explained the role of herbal plants in the treatment of COVID-19 in addition to Western treatment. Studies have shown that nutrition has an effective role in treating the virus, as foods rich in vitamin C are used to treat respiratory viruses. Plant food such as fenugreek, curcumin, cinnamon, and black pepper that are rich in bioactive compounds can be of help in treating COVID.

Despite significant efforts in drug discovery and development, combating Coronavirus Disease (COVID-19) still remains to be an increasingly challenging health problem because of the fact that the recommended current therapies are intended only for the symptomatic treatment and/or prophylaxis of SARS-CoV-2 infections/ COVID19 patients, but do not cure the disease. In this context, several complementary and alternative, but potential healthcare practices (CAMs) that could effectively boost host immunity are firmly believed to be one of the major medical interventions for the prevention as well as control of COVID-19. In this review, several immunity-boosting measures based upon traditional healthcare practices including traditional herbal remedies, home remedies, and alternative and complementary therapies including yoga and naturopathies to fight against SARS-CoV-2 infections/ COVID-19 have been reviewed

Coronavirus disease 2019 (COVID-19) is a unique disease caused by the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that has caused mortalities throughout the world. This unique coronavirus is extremely contagious and has no effective therapy or particular medications. It caused increased worldwide mortality and lockdown. The Food and Drug Administration (FDA) has permitted the use of COVID-19 vaccination in this emergency situation. However, there are concerns regarding the new COVID-19 vaccine's safety, effectiveness, and long-term protection. A deteriorated immune system is an eminent risk factor for viral influenza infections. Many individuals all around the world are interested in herbal nutraceuticals to preserve their health and strengthen their immune systems. The use of dietary supplements, herbal medications, and foods with protective benefits, such as functional foods, improves the immune system's ability to avoid and control pathogenic viral infections. 

SARS-CoV-2 (Severe acute respiratory syndrome coronavirus 2) leads to coronavirus disorder (COVID-19). It was detected in Wuhan City, China, in December 2019 and extended to different provinces in China. The drug discovery strategy that holds the thrust of the COVID-19 pandemic is the existing trial of broad-spectrum antiviral drugs. However, molecular docking combined with chemical synthesis assists in discovering various synthetic agents, above one-third of FDA (Food and Drug Administration)- are naturally occurring products as approved drugs. Natural derivative products from different sources of fungus, plant and marine have been abundant in nutrition/ phytochemicals to prevent various disease discoveries for many diseases’ prevention. There are scarcely any country that is left intact by the coronavirus outbreak. Only the considerable well-known health threat still now requires it to be managed as early as possible. To date, there is no development of drugs or vaccines that have been proven clinically against COVID-19. Various secondary phytoconstituents with antiviral activities have been extracted from medicinal herbs. Different research works have been demonstrated all over the globe to find antiviral medication effectiveness against SARS-CoV-2 in COVID-19 pandemic. The best preventive measures against COVID-19 infections would be searching for the molecules responsible for modifying or disturbing any pathways related to the virus replication cycle. Natural compounds are capable of altering or inhibiting the configuration of the structural protein of (spike glycoprotein), non-structural proteins (3-chymotrypsin-like protease, papain-like protease, helicase, and RdRP) and accessory proteins encoded by the SARS-CoV-2 genome that are required to be investigated.Hence, various natural products and herbal extracts may prove as potent therapeutics in treating the symptoms related to SARS-CoV-2 infection. In this context, we will present some traditional plants/herbs that are found effective against viral activities and reduce the contamination risk by Coronavirus and cure some symptoms of COVID-19, mainly respiratory problems.