Potentiation of analgesic activity following the complexation of Algrizea minor Sobral, Faria & Proença (Myrteae, Myrtaceae) leaf essential oil with β-cyclodextrin

Pain is a fundamental biological process; however, its acute manifestation may result in dysregulation and tissue injury. The Myrtaceae family is well known for its diverse pharmacological activities, and Algrizea minor, a species native to Brazil, has traditionally been used for the management of inflammation and pain. The present study investigated the antinociceptive properties of essential oil Algrizea minor (EOAm) and examined whether its complexation with β-cyclodextrin (β-CD) could enhance its pharmacological efficacy. EOAm was obtained by hydrodistillation, yielding 0.57% (w/w), with β-pinene (66.99%) identified as the major constituent. Antinociceptive activity was evaluated using murine models, including the acetic acid-induced writhing and formalin tests. Free EOAm significantly reduced nociceptive behavior in a dose-dependent manner, producing up to 89% inhibition in the acetic acid model. Remarkably, complexation with β-CD further potentiated the analgesic effect, achieving complete inhibition of nociception at the highest dose tested (200 mg/kg). In the formalin assay, both EOAm and its β-CD complex displayed significant efficacy during the neurogenic and inflammatory phases. Partial reversal of the analgesic effect by naloxone indicates the involvement of the opioid system in the underlying mechanism. Overall, these findings demonstrate that EOAm possesses strong antinociceptive activity, which is further enhanced through β-cyclodextrin complexation. This approach not only improves efficacy but also may increase the stability and bioavailability of the essential oil, highlighting the EOAm/β-CD complex as a promising candidate for the development of novel analgesic therapies.

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