Aqueous extract of Psidium glaziovianum Kiaersk leaves acts on muscarinic and opioid receptors and reduces cytokines and inflammatory infiltrates in vivo models.

Pain and inflammation are essential physiological processes, yet their dysregulation contributes to chronic pathological conditions. Conventional analgesic and anti-inflammatory therapies often cause adverse effects, highlighting the need for safer alternatives. Psidium glaziovianum (Myrtaceae) is a medicinal species rich in bioactive compounds with potential pharmacological activity. This study evaluated the analgesic and anti-inflammatory properties of the aqueous extract of P. glaziovianum leaves (EAPg) in experimental models of nociception and inflammation. Chromatographic and UV-Vis analyses revealed the presence of flavonoids and ellagic acid. EAPg induced a dose-dependent antinociceptive effect, with the 100 mg/kg dose being the most effective in reducing nociceptive behaviors in acetic acid and formalin tests and increasing latency in the tail immersion test, suggesting both peripheral and central actions. Pretreatment with naloxone and atropine partially reversed the antinociceptive effects, indicating the participation of opioid and muscarinic receptors. In inflammatory models, EAPg significantly reduced paw edema and leukocyte recruitment and decreased TNF-α and IL-1β levels, demonstrating potent anti-inflammatory activity. Collectively, these findings provide the first evidence that EAPg exerts dual (central and peripheral) antinociceptive and anti-inflammatory effects mediated through opioid and muscarinic pathways, supporting its pharmacological potential as a natural analgesic and anti-inflammatory agent.