Anti-inflammatory potential of β-amyrin, a triterpenoid isolated from Costus igneus

Costus igneus, common name Fiery Costus or Spiral Flag, is a species of herbaceous plant in the Costaceae family. It is cultivated in India for its use in traditional medicine especially for diabetes. The present study was carried out to determine the mechanism of anti-inflammatory action of β-amyrin isolated from the leaves of Costus igneus (C. igneus) using carrageenan-induced rat model and LPS-induced human peripheral blood mononuclear cells (hPBMCs) in vitro model. The differential fractionation of leaves of Costus igneus showed maximum percentage inhibition of paw edema at a dose of 100 mg/kg body weight in methanolic extract (MEC). MEC elicited significant anti-inflammatory effect by inhibiting cyclooxygenase (COX), lipoxygenase (LOX), myeloperoxidase (MPO) and nitric oxide synthase (NOS) activities in monocytes when compared to carrageenan control. The effect of MEC was more pronounced than standard drug Diclofenac (20 mg/kg body weight). After fractionation of MEC using various solvents such as chloroform, hexane, ethyl acetate and butanol, the mechanism of anti-inflammatory effect of chloroform extract (CEC) of MEC was evaluated since it showed maximum beneficial effect at a dose of 50 mg/kg BW Treatment of carrageenan-induced rats with CEC exerted significantly decreased COX-2, MPO, and NOS activities when compared to carrageenan-induced rats. By the partial purification of CEC by liquid-liquid partition chromatography, TLC, mass, IR and NMR spectroscopy, the active component β-amyrin was isolated. Significant decrease in edema was observed by the administration of β-amyrin in a dose-dependent manner and 100 µg of β-amyrin showed 97 % in carrageenan-induced paw edema in rats. Treatment with β-amyrin significantly inhibited PGE2, IL-6 secretion, and NF-κB activation in a concentration-dependent manner on LPS-induced hPBMCs. Thus, β-amyrin, an active component isolated from C. igneus, serves as a promising and expanding platform for treatment of various inflammatory disorders.