Fractionation and bioassay-guided isolation of antihypertensive components of Senecio serratuloides

Senecio serratuloides commonly referred to as “two day cure” is used in folk medicine for treating hypertension and wounds in South Africa. This study was aimed at isolating and testing the antihypertensive effects of bioactive compounds from S. serratuloides. Senecio serratuloides was serially extracted using solvents of increasing polarity. Phytochemical analysis, antioxidant capacity and antihypertensive properties of fractions were investigated. Bioactive compounds were isolated from ethyl acetate and methanol fractions, their antihypertensive effects and effect on urine norepinephrine concentration were determined. Ethyl acetate and methanol fractions had all eight phytochemicals tested, better antioxidant capacity and significantly (p < 0.001) prevented the increase in blood pressure induced by Nω-Nitro-l-arginine methyl ester hydrochloride. The isolated bioactive compounds were phytosteroids and Estran-3-one, 17-(acetyloxy)-2-methyl-, (2à,5à,17á) – which was isolated from methanol fraction had significantly (p < 0.001) better antihypertensive effects through the 4-h period of the study. Senecio serratuloides may be a potential source of antihypertensive lead compounds