Renin inhibition activity, phenolic and flavonoid contents of Centella asiatica (L.) Urb.

Context: Centella asiatica (L.) Urb. and its components may have antihypertensive effects through renin inhibition. Aims: To assess the in vitro renin inhibitory activity of extracts with various solvents from the C. asiatica leaves and asiaticoside, asiatic acid, madecacosside, and madecaside acid. Additionally, the study evaluates each extract's total phenolic and flavonoid contents. Methods: Renin inhibitor activity in vitro was assessed using the renin inhibitor screening assay kit. Total phenolics and total flavonoid contents were spectrophotometrically measured using Folin-Ciocalteu and aluminum chloride, respectively. Results: The extracts of ethanol, hexane, ethyl acetate, and butanol have renin inhibitory activity with IC50 = 1.329, 23.73, 53.76, and 61.38 μg/mL, respectively. Meanwhile, asiaticoside, asiatic acid, madecacosside, and madecaside acid showed IC50 = 2.09, 63.65, 48.2, and 38.12 μg/mL, respectively. Aliskiren, as a reference, exhibited an IC50 = 3.56 × 10-3 μg/mL. The total phenol levels for ethanol, hexane, ethyl acetate, and butanol extracts were 61.03 ± 3.44, 45.75 ± 0.77, 49.60 ± 2.33, and 76.78 ± 3.44 mgGAE/g, respectively. The total flavonoid contents were 51.95 ± 0.74, 70.01 ± 0.50, 50.46 ± 0.53, and 72.95 ± 1.28 mg QE/g, respectively. Conclusions: The ethanol extract showed the lowest IC50 value, indicating better renin inhibitory potency. Asiaticoside may inhibit renin because its IC50 is lower than the other three. Since butanol extract displayed the highest total phenol and flavonoid contents, it could inhibit renin due to its antioxidant qualities.