Evaluation of the treatment of fever, pain and inflammation with Indigofera suffruticosa Miller Leaves Aqueous Extract

Ethnopharmacological relevance: Indigofera suffruticosa has reports of its popular use for analgesy in several cultures. Besides that, all parts of this plant are used for some medicinal outcome. The leaves are used in teas, decoctions, juices and included in baths for treating fever and inflammatory processes. Aim of the study: To evaluate the anti-inflammatory activity mechanisms of I. suffruticosa leave aqueous extract (IsAE). Materials and methods: Phytochemical screening of IsAE was performed by thin layer chromatography. Total flavonoid content was determined and expressed by milligram of quercetin equivalent per gram of extract (mgEQ/g). 50% of the lethal dose that kills animals (LD50) was determined by acute toxicity in mice. Anti-inflammatory activity was evaluated through carrageenan-induced paw edema, peritonitis, and protein denaturation inhibition. Anti-nociceptive potential was evaluated by acetic acid-induced writhing and formalin tests. Antipyretic activity was assessed by yeast-induced fever. Results: Phytochemical analysis revealed the presence of flavonoids and acid gallic in a quantity of 33.9 mg QE/g. Acute toxicity evaluation resulted in a LD50 of 3807.88 mg/kg. For carrageenan-induced paw edema test, IsAE in both doses (20 and 100 mg/kg) reduced the edema in 83.93%. IsAE reduced nitric oxide (NO) production and leucocytes migration to peritonitis inflammation site and at a concentration of 0.5 mg/mL showed also inhibition of protein denaturation similar to indomethacin in the same concentration. IsAE inhibited in 72.60% the number of contortions in writhing test. In formalin test, IsAE was also efficient, but showed results only in the second phase. In addition, the concentration of 100 mg/kg reduced fever significantly. Conclusions: IsAE proved to be anti-inflammatory, acting in different parts of the inflammation process, confirming its popular use.