Abstract
Several antiviral natural products have been traditionally obtained from marine and land sources. In addition, new compounds with promising antiviral are emerging from novel sources such as agri-waste and the larvae of certain species. This chapter reviews the various sources of natural compounds/extracts which exhibited in vitro and in vivo antiviral activities with emphasis on anti-influenza activity. Comparison between these natural products and other allopathic medicine alternatives in terms of safety and the potential of other benefits conferred will be briefly discussed. The active compounds responsible for the antiviral activity and their mode of action will be critically reviewed with the aim of establishing a structure–activity relationship and to describe potential routes for synthesis of comparable structures. Future use of natural sources as antiviral activity and required products characteristics will be discussed to provide guidelines for future research.