Anti-inflammatory efficacy of Mangifera indica stem-bark, carica papaya and eucalyptus leaf extracts on formalin-induced inflammation in rats

Inflammation is part of the body's defense mechanism and can be acute or chronic. Inflammatory disease prevalence is on the increase in Africa and anti-inflammatory efficacious alternatives are continually sought for.  Effects of herbal remedies consisting of ethanol extracts of Mangifera indica Stem-bark (MSB), Carica papaya (PL) and Eucalyptus (EU) leaf extracts were evaluated on formalin-induced inflammation in albino rats using standard procedures. Forty-five (45) rats were divided into nine (9) groups of five (5) rats each. Induction was by subcutaneous injection of 0.1ml (2.5% v/v in normal saline) formaldehyde solution (formalin) via the right hind paw of all groups except normal control, group seven (7), on 1^st & 3^rd day of experiment. Groups 1-3 were treated with 200mg/kg, 400mg/kg, and 600mg/kg combined ethanol extracts MSB+PL respectively. Groups 4-6 received 200mg/kg, 400mg/kg, and 600mg/kg combined extracts of MSB+EU respectively. Group 8(Standard) received 5mg/kg piroxicam and group 9(negative control) received 5ml/kg normal saline for 10 days. Paw thickness and body weights taken on days 3, 7&10. MSB+EU combination was most efficacious and effect was dose-dependent. Tumor necrosis factor alpha (TNFα) and ESR (erythrocyte sedimentation rate) did not significantly differ between the groups. White blood cells (WBC), Malondialdehyde (MDA) were highest in untreated group and platelet count lowest. There were no significant changes in liver marker enzymes except in MSB+EU 600mg/kg group, which also corroborated histological findings. The study therefore justifies the anti-inflammatory use of both extract combinations and suggests MSB+EU maybe most effective, however, questions are raised on its effect on liver integrity. Further studies on human clinical parameters and anti-inflammatory properties of these extract over an extended period is suggested to further confirm their potential role in anti-inflammation as well as determination of anti-inflammatory effect of these extracts on immunological pro-inflammatory molecules (IL-6, IL-IB, TNF-a).