Antinociceptive and anti-inflammatory properties of hydroethanolic seed extract of Monodora myristica (Annonaceae) in rodents

Background: Monodora myristica (Gaertn) Dunal (Annonaceae) is used in traditional medicine for cough, rheumatism, hemorrhoids, diabetes, anemia and headaches.

Objective: This study was carried out to investigate the antinociceptive and anti-inflammatory effects of the hydroethanolic seeds extract of Monodora myristca (HMM) in rodents.

Methods: HMM (50-200 mg/kg, p.o.) was administered 1 h before intraperitoneal or intraplantar injection of 0.6%V/v acetic acid or 1% formalin (20 µL), respectively, to evaluate the antinociceptive property. Acute and chronic anti-inflammatory effect was investigated using carrageenan-induced paw and xylene-induced ear oedema, and cotton-pellet induced granuloma tests, respectively.

Results: HMM (50-200 mg/kg) produced dose dependent and significant decrease in mean number of writhes in acetic acid-induced nociception and increased pain threshold to neurogenic and inflammatory pain with 48.59 and 34.2% inhibition, respectively, in the formalin-induced nociception assay. The HMMinduced antinociception was completely blocked by pre-treatment of mice with naloxone, pChlorophenyalanine (serotonin synthase inhibitor; 100 mg/kg, i.p.) and sulpiride (D2 receptor antagonist; 50mg/kg) whereas glibenclamide (KATP sensitive channels blocker; 10 mg/kg) failed to reverse the antinociceptive effect of the extract. In acute inflammatory model, HMM produced time course inhibition of carrageenan-induced paw oedema. In addition, pretreatment of mice with HMM inhibited xylene-induced ear oedema by 60% comparatively similar to the effect of dexamethasone (83.90%). Moreover, in the cottonpellet granuloma pouch, HMM (200 mg/kg) reduced granuloma formation by 52%.

Conclusion: The hydro-ethanolic seed extract of M. myristica possesses antinociceptive effect mediated through interaction with opioidergic, serotonergic and dopaminergic systems and an anti-inflammatory action through inhibition of inflammatory mediator's release. Finally, the study established the scientific basis for its use in the management of pain and inflammatory conditions in traditional medicine.