Anti-inflammatory, Analgesic and Antipyretic Properties of Ethanolic Extracts of Three Plants of Beninese’s Pharmacopoeia: Euphorbia hirta, Citrus aurantifolia and Heterotis rotundifolia

Background/Objective: Euphorbia hirta, Citrus aurantifolia and Heterotis rotundifolia are commonly used in Benin in the treatment of infectious diseases. The aim of this study is to evaluate the anti-inflammatory, analgesic and antipyretic properties of ethanolic extracts of these plants.

Materials and Methods: The study was carried out on 30 wistar rats placed in 6 work lots. A positive control lot having received diclofenac and a negative control lot having received physiological water were used. The ethanolic extract of the plants was used at a dose of 200 mg / kg bw. The model of inflammatory edema of the rat paw induced by 2% formalin was used. Analgesic activity was assessed by the pain method induced by 3% acetic acid and the tail immersion method with wistar rats. The antipyretic effect was evaluated on pyrexia induced by brewer's yeast at 20% with wistar rats.

Results: After injection of formalin to animals, inflammatory reaction was almost immediate with appearance of classic signs of acute local inflammation (Redness, pain, heat and edema) at the five experimental groups. This inflammatory reaction occurs in two phases. The first phase occurs between 0 and 2 hours after injection of phlogogenic agent and the second phase, initiated after two hours extending to the fifth hour and even beyond. Administration of these extracts prevents edema inflammatory and inhibition percentages of edema vary between 23.67% and 86.76% for the three extracts. These extracts have similar anti-inflammatory activity (p> 0.05) to that of diclofenac at 50 mg/kg. Analgesic activity show that these extracts inhibit very significantly (p<0.001) chemical pain induced by acetic acid and the highest inhibition percentage is 60.34% (Citrus aurantifolia). This percentage is like to that of acetylsalicylic acid (67.35%) administered at the same dose. Likewise, these extracts attenuate significantly (p <0.05) thermal pain induced by tail immersion of each rat in hot water at 50°C. Indeed, these extracts, reduces very significantly (p <0.001) pyrexia induced by 20% beer yeast suspension in rats and they have similar effect (p> 0.05) to that of acetylsalicylic acid at the fourth hour.

Conclusion: These results show that the plants studied have the pharmacological properties evaluated. These results justify the use of these plants in traditional medicine.