Investigation of in vivo anti-inflammatory and anti-angiogenic attributes of coumarin-rich ethanolic extract of Melilotus indicus.

Abstract

Inflammation and angiogenesis are two major contributors to tumourigenesis. Melilotus indicus is traditionally used as an anti-inflammatory agent. The current study was designed to investigate the anti-inflammatory and anti-angiogenic properties of ethanolic extract of M. indicus (Miet) whole plant and its marker compound (coumarin) using a series of in vivo methods. Extraction by maceration was adopted to prepare ethanolic extract. Phytochemical compounds present in Miet were investigated using both qualitative and quantitative methods. In vivo safety profile of Miet was investigated in behavioural studies. Four acute oedema models such as carrageenan, serotonin, histamine-induced paw oedema and xylene-induced ear oedema, and chronic formaldehyde-induced paw oedema model were employed to explore the anti-inflammatory potential of Miet. Chorioallantoic chick membrane assay (CAM) was performed to explore anti-angiogenic potential of Miet. Histopathological evaluations were conducted to access improvement in skin texture of paws. TNF-α ELISA kit was used to study effects of treatment on serum levels of TNF-α. Extraction by maceration resulted in formation of greenish coloured semisolid extract with a high coumarin content. In vivo toxicological studies revealed LD50 of Miet was greater than 8000mg/kg. Data of acute inflammatory models depicted significant (p < 0.05) inhibition of oedema in Miet, coumarin and standard (piroxicam/indomethacin) treated groups. 750mg/kg of Miet induced comparable (p > 0.05) anti-inflammatory effects to that of standard-treated groups. Coumarin showed better anti-inflammatory effects in carrageenan-induced paw oedema model as compared with histamine- and serotonin-induced oedema models. Data of chronic inflammatory models also depicted dose-dependent anti-inflammatory attributes of Miet which were comparable with standard treated groups. Significant (p > 0.05) downregulation of TNF-α in serum samples of animals treated with Miet and piroxicam was observed as compared with control group. Furthermore, Miet significantly halted blood vessels formation in CAM assay. Overall, data of the current study highlight that M. indicus has anti-inflammatory and anti-angiogenic potentials, and, thus, can potentially be used as an adjuvant therapy in solid tumours management.