Plant-Derived Compounds: A Potential Treasure for Development of Analgesic and Antinociceptive Therapeutics

Pain is one of the most pervasive health problems associated with a negative impact on thinking, mood, psychological, and social communication. The medicinal plants and their derived compounds have recently attracted great interest as potential candidates for defeating pain because of their worldwide safety, availability, and affordability. This review was constructed to summarize all in vitro and in vivo studies and clinical trials regarding plant-derived compounds' analgesic and antinociceptive effects. Further, we focus on structural aspects, molecular mechanisms, and pharmacological effects. A literature survey was performed in "PubMed," "Science Direct," and "Google Scholar," using the keywords "Pain, Analgesic activity, Flavonoids, Phenolics, Medicinal plants, Volatile oils, Tannins, Saponins, Alkaloids" to assess the activities of each compound. The main natural compounds studied were flavonoids, alkaloids, phenolic acids, lignans, anthraquinones, and volatile oils. Different in vitro studies utilized nucleus pulposus cells, VK2/E6E7, End1/E6E7, and LPS-stimulated RAW264.7 cells to assess analgesic effects. The frequently defined animal models of analgesic activity included acetic acid-induced abdominal constrictions, hot-plate test, tail-flick test, formalin test, complete Freund's adjuvant-induced pain, and hind paw incisional surgery. For the natural compounds described, the opioids, serotonergic, and cannabinoid receptors appeared to be the most promising targets for pain management. This review suggested a wealthy resource of natural compounds as analgesic and antinociceptive candidates for pharmacists and drug researchers to launch a new drug with promising efficacy and safety.