Anti-Inflammatory Effects of the Aqueous Extract of Leaves of Vernonia colorata (Willd.) Drake (Asteraceae) in Wistar Rats and NMRI Mice

Vernonia colorata leaves are traditionally used in Africa to treat various diseases, including inflammation. This study aimed to evaluate the anti-inflammatory effects of the aqueous extract of Vernonia colorata leaves (AEVC) on both acute and subacute inflammation models. Inducers of acute inflammation, such as dextran and carrageenan-induced paw edema in rats and mice, were used to assess the effect of the extract on this type of inflammation. Moreover, the induction of abdominal granuloma with cotton and paw edema with formalin allowed to evaluate the extract's anti-inflammatory activity in both acute and subacute settings. The results indicated that in the dextran model, AEVC produced an anti-inflammatory effect from early time points, with a maximum inhibition of 63.55 ± 6.80% at a dose of 250 mg/kg after 1.5 hours. In the carrageenan-based model, all the doses of extract significantly (p < 0.05) reduced paw edema volume, with the highest inhibition being 58.39 ± 4.23% at 250 mg/kg at 6 hours, compared with the control. For cotton pellets, fresh granuloma weight was significantly inhibited (p < 0.05) at 250 mg/kg, while dry granuloma weight showed significant reduction (p < 0.05) at 100 and 250 mg/kg compared with the control (NaCl). In formalin-induced inflammation, reductions in edema volume were statistically significant (p < 0.01) across all the doses, compared with the control. Histopathological analysis showed that treatment with the extract significantly decreased inflammatory cell infiltration and reduced formalin-induced edema. The extract would thus block the release of histamine, serotonin, and prostaglandins by preventing vascularization. These findings suggest that Vernonia colorata leaves might be beneficial in managing inflammatory diseases.