Neuronal nitric oxide synthase enzyme activation and calcium channel-dependent relaxation of the internal anal sphincter by Tridax procumbens

Objective: To investigate the role of neuronal nitric oxide synthase (nNOS) enzyme activation and calcium channel-dependent mechanisms in mediating the relaxation of the internal anal sphincter (IAS), with specific reference to the pharmacological effects of Tridax procumbens. Data sources: Relevant literature was retrieved from PubMed/MEDLINE, and Google Scholar encompassing published review articles, pharmacological studies, phytochemical investigations, and clinical research related to T. procumbens. Study selection: Published literature describing the phytochemistry, pharmacological activities, therapeutic uses, and formulations of T. procumbens, along with studies on nNOS activation, calcium channel-dependent relaxation, and IAS physiology were included in this review. Only peer-reviewed, English-language articles were considered. Studies with insufficient data, duplicates, and non-peer-reviewed sources were excluded. Summary of contents of the article: Anal fissure results from internal anal sphincter hypertonicity causing ischaemia, spasm, and pain. T. procumbens shows consistent smooth muscle relaxant effects via calcium channel inhibition and nitric oxide release across preclinical studies. A recent randomized controlled trial confirmed its clinical efficacy, matching standard Lignocaine-Nifedipine cream in healing, spasm, and pain relief, with fewer side effects. Conclusion: T. procumbens, acting as a safe chemical sphincterotomy through nitric oxide and calcium-mediated sphincter relaxation, warrants consideration as a first-line treatment for anal fissure. Keywords: Calcium Channels L-Type, Fissure in ano, Internal Anal Sphincter, Neural Nitric Oxide Synthase, Tridax procumbens