The effects of Cissampelos pareira (Linn), Lantana camara (Linn) and Ocimum gratissimum (African basil) leaf extracts on pain have not been biologically determined despite their frequent traditional use in pain management. The present study evaluated the effects of methanol leaf extracts of these three plants on formalin-induced pain in Swiss albino mice. Leaves of C. pareira, L. camara and O. gratissimum were harvested, cleaned, shade dried, crushed, extracted in absolute methanol and concentrated to dryness. The quantitative phytochemical screening of the three plant extracts was first carried out. Then, the pain assay tests constituted eight groups of five mice each: normal control group, positive control group, negative control group and experimental groups of 50, 100, 150, 200 and 250mg/kg bw extracts. The animals were administered with various treatments thirty minutes before induction of pain through injection of 0.01ml of 2.5% formalin solution into the sub-plantar region of the left hind paw. Paracetamol at the dose of 50mg/kg bw and 5% dimethyl sulfoxide were used as the positive and negative controls respectively. The plant extracts were administered intraperitoneally and orally. Data was analyzed using one-way analysis of variance and unpaired t-test. Phytochemical screening on separate extracts of C. pareira, L. camara and O. gratissimum revealed fatty acids, phenols, flavonoids and terpenoids. The different dosages of methanol leave extracts of C. pareira, L. camara and O. gratissimum reduced pain significantly (p˃0.05) in mice. The significant reduction of pain was associated with fatty acids, phenols, flavonoids and terpenoids revealed in the plant extracts.
Key words: Cissampelos pareira, Lantana camara, Ocimum gratissimum, Antinociception, Phytochemicals
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