Anti-inflammatory and antinociceptive effects of Annona muricata L. (Annonaceae) leaves extract
Annona muricata L, or soursop is a plant which has been reported to have various pharmacological and nutritional properties . In Malaysia, it has been used for boils, coughs, diarrhea, dermatosis, hypertension, rheumatism, and to reduce bleeding. The objectives of this study are to investigate the anti-inflammatory and antinociceptive effects of ethanolic extract of Annona muricata L using carrageenan-induced paw oedema test  and acetic acid-induced abdominal writhing test . Paw volumes of rats were measured before inducing oedema and measured again at every half hour for four hours after carrageenan injection using plethysmometer. Then, the changes of paws volume were calculated and expressed in percentage of swelling. A dose-dependent inihibitory effect was exhibited in the carrageenan-induced paw oedema test, where at doses of 10, 30, 100 and 300 mgkg-1, the extract significantly reduced (p<0.05) the oedema by 40.22%, 61.14%, 62.25% and 79.30% respectively at the optimum oedema (90 minutes). At higher dosage of 100 mgkg-1 and 300 mgkg-1, the anti-inflammatory response was comparable with 10 mgkg-1 indomethacin. In the abdominal writhing test induced by 0.6% acetic acid, the number of writhing was counted every 5 minutes for 1 hour to investigate the antinociceptive effect. At 30, 100, and 300mg/kg, it significantly inhibited the nociceptive response (p<0.05) in mice. The ED50 obtained for the anti-inflammatory and antinociceptive effects were 16.6mg/kg and 112.20mg/kg respectively and it's LD50 calculated from toxicity study was 859mg/kg. In conclusion, ethanolic extract of Annona muricata L possess both anti-inflammatory and antinociceptive effects in dose-dependent manner.
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