The anti-nociceptive effects of ethanol extract of aerial parts of Schkuhria pinnata in mice

Abstract

Ethnopharmacological relevance: The growing challenge to access conventional analgesics, contraindications, and adverse effects could have led individuals to use Schkuhria pinnata (Lam.) Kuntze ex Thell. (Compositae), as an alternative traditional therapeutic strategy for pain. However, evidence of its safety and efficacy is scarce. Aim of the study: This study evaluated the anti-nociceptive effect of the ethanol extract of the aerial parts of S. pinnata in mice. Methods: The mice were randomly assigned to nine groups: (1) vehicle; (2) acetylsalicylic acid (intraperitoneally 150 mg/kg); (3) pentazocine (intramuscularly 1.0 mg/kg); (4 a & b) orally 100 mg/kg extract; (5 a & b) orally 200 mg/kg extract; (6 a & b) orally 400 mg/kg extract. We used an acetic acid-induced writhing model and a tail-flick test. The number of writhes and time taken for the tail to flick was recorded. A one-way analysis of variance followed by Tamhane T2 post hoc was used for multiple comparisons. Results: Compared to a vehicle (59.0 ± 2.68), S. pinnata ethanol extract at a dose of 200 and 400 mg/kg, p.o reduced writhes to 42.5 ± 1.12 and 27.0 ± 2.62, (p < 0.05) respectively. Similarly, the pain threshold of mice increased dose-dependently; doses of 200 and 400 mg/kg, increased time to 5.33 ± 0.42 and 8.67 ± 0.21 min, (p < 0.05) respectively. The extract had an EC50 of 348.8 mg/kg and acute toxicity established an LD50 of 1224.8 (95% CI: 952.2–1575.3). Conclusion: S. pinnata ethanol extract had anti-nociceptive activity by central and peripheral mechanisms that could justify its traditional use in pain management. Further studies could now focus on identifying active fractions and pure isolated compounds responsible for anti-nociceptive activity