Since ancient times, plants have always been a reliable and important source of bioactive compounds used to treat several diseases, and thus play a central role in human health. In addition, medicinal plants are a rich source of bioactive secondary metabolites that have a wide range of medicinal uses. This is the reason why, currently, 90% of drugs come from natural or semisynthetic origins. Chemical diversity of plants made them one of the main sources for the extraction and purification of secondary metabolites. On the other hand, pain has always been a cause of concern to humans who searched for a remedy from natural sources, mostly from plants. In this respect, substances that relieve pain (algesia) can be described as analgesics (painkillers). Chemically diverse structures have been identified as pain relievers; they relieve pain through various mechanisms and act either centrally (opioids receptor agonism) or peripherally. Therefore, this chapter is intended to summarize the literature pertaining to plants and their constituents discovered with analgesic potential in the last four decades.
Part of the book: Pain Relief