Medicinal and Therapeutic Potential of Herbs and Plant Metabolites / Extracts Countering Viral Pathogens - Current Knowledge and Future Prospects

Background: Recently, there has been a remarkable progress in the field of antiviral herbal therapy owing to increasing concerns about the development of drug resistance and limited advances in the field of antiviral drug discovery. In almost all countries, medicinal plants have been used widely throughout history for the treatment of diseases and infections as traditional healing remedies due to their broad therapeutic spectrum and minimal or no side effects. As synthetic antiviral drugs are not available against most of the viral agents, hence all possible efforts have been focused on the search for new drugs and complementary/alternative medicines from different herbal formulations. Methods: We have retrieved the related information from the online published resources (Medline, PubMed, Pub- Med Central, Science Direct and other scientific databases); which were further analyzed and compiled. Results: Medicinal plants contain extractable biochemical and bioactive compounds, which can target certain viruses or can cure or prevent several viral diseases and infections. Despite their long history of use, the research and scientific evidences regarding the use of medicinal plants and natural products as prophylactics, therapeutics, and their health multiple beneficial applications have only gained momentum in past few decades. Many scientific studies have been undertaken, which range from the separation of active substances to the comprehension of the therapeutic mechanisms of antiviral herbs, their potent applications in the neutralization of viral pathogens and clinical trials. Consequently, hundreds of herbs and plant metabolites have been screened, identified, and tested for their antiviral activities; fortunately, some have shown significant medicinal activity in the amelioration or prevention of various viral diseases in both preclinical and clinical studies. Conclusion: This review addresses the scientific significance of various herbal formulations of different medicinal plants and their extracts, which have shown promise or been proven effective for the treatment of diseases caused by various viral pathogens, including emerging and re-emerging viruses that infect humans, animals, poultry and fish.