Phytochemical and pharmacological studies on Leonotis leonurus

The present study aimed at isolation of the flavonoid constituents of Leonotis leonurus R. Br. (Lamiaceae) flowering aerial parts, identification of the isolated compounds, and evaluation of the hepatoprotective, anti-inflammatory and cytotoxic activities of the aqueous alcoholic and chloroform extracts. Isolation of the flavonoid constituents was performed using chromatographic techniques. Ten flavonoid compounds were isolated and identified as six flavone glycosides, two methylated flavones, and two flavone aglycons. The structures were established through chemical and spectral analysis. Paracetamol-incluced hepatotoxicity, carrageenan-induced hind rat paw edema and sulforhodamine B (SRB) assay were used in the evaluation of hepatoprotective, anti-inflammatory and cytotoxic activities, respectively. The 70% methanol and chloroform extracts showed strong hepatoprotective and anti-inflammatory activity; no cytotoxic activity was observed at the chosen extract concentrations and they possess promising protective activity against paracetamol-incluced hepatic damage and anti-inflammatory activity in rats. The flavonoids isolated from Leonotis leonurus in this study were found to be isolated for the first time from the genus Leonotis.