Plant-Based Therapeutics Against Communicable Diseases: A Review of Ethnopharmacology and Medicinal Chemistry Approaches.

Infectious diseases are traditionally managed using medicinal herbs in traditional Chinese medicine, Ayurveda and Unani. These conventional therapies are an essential source of new anti-infective drugs considering antimicrobial resistance threatens global public health. The present review critically appraises the use of medicinal plants against bacterial, viral, fungal and parasitic infections in combination with medicinal chemistry and ethnopharmacology. A comprehensive review of ethnobotanical data, phytochemistry and pharmacological studies was performed on the basis of WHO classification of infectious diseases in order to identify repeating medicinal plants and their active ingredients. Over 150 medicinal plants have been discovered by major ethnomedical systems in the course of history and have been used as the remedy of infectious diseases. Essential phytochemicals such as alkaloids, terpenoids, flavonoids, phenolics and saponins showed broad-spectrum anti-infective activity via mechanisms including membrane damage, enzyme inhibition, oxidative stress regulation and interference with nucleic acid synthesis. Some examples of such successful combination of ethnopharmacology with pharmacology include artemisinin, berberine, andrographolide and glycyrrhizin. Nevertheless, the lack of standardization, poor bioavailability and insufficient clinical trials are still problematic.