Pharmacology, Phytochemistry, Toxicology and Micropropagation of Spilanthes acmella (L.) Murr.: A Comprehensive Review

Spilanthes acmella (L.) Murr., commonly known as the toothache plant or eyeball plant, is an important medicinal herb belonging to the family Asteraceae. The plant is widely distributed in tropical and subtropical regions and has been extensively used in traditional medicine for the treatment of toothache, oral infections, inflammation, rheumatism, fever, and skin diseases. The therapeutic potential of S. acmella is mainly attributed to the presence of bioactive alkamides, particularly spilanthol, along with flavonoids, phenolics, triterpenoids, phytosterols, coumarins, and essential oils. Numerous pharmacological investigations have demonstrated its antimicrobial, anti-inflammatory, analgesic, antioxidant, antimalarial, hepatoprotective, anti-obesity, vasorelaxant, and insecticidal activities. Recent toxicological studies suggest that the plant exhibits relatively low toxicity at therapeutic doses. However, increasing commercial demand and habitat depletion have raised concerns regarding its conservation. Consequently, in vitro micropropagation techniques have been developed to facilitate large-scale cultivation and sustainable utilization. This review summarizes the ethnomedicinal uses, phytochemical constituents, pharmacological activities, toxicological profile, and advances in micropropagation of S. acmella, highlighting its significance as a promising medicinal and industrial plant.