Caffeoyl-β-D-glucopyranoside and 1,3-dihydroxy-2-tetracosanoylamino-4-(E)-nonadecene isolated from Ranunculus muricatus exhibit antioxidant activity.

This study evaluates the antioxidant activity of Ranunculus muricatus and isolation and structure elucidation of the active constituents. The aerial parts of the plants were shade dried at room temperature and powdered and extracted with methanol. The free radical scavenging activity was evaluated by 1,1-diphenyl-2-picryl-hydrazyl (DPPH) assay. The percentage scavenging activity was determined based on the percentage of DPPH radical scavenged. Column chromatography was used in order to isolate the active compounds. Spectral techniques UV, IR, ¹H NMR, ¹³CNMR and HREI-MS were used for the structure elucidation of the isolated compounds. Two isolated compounds, A (caffeoyl-β-D-glucopyranoside) and B (1,3-dihydroxy-2-tetracosanoylamino-4-(E)-nonadecene), exibited a significant antioxidant activity as showed by DPPH radical scavenging method. Percentage inhibition for compound A (at 0.5 mM) was 82.67 ± 0.19 with IC₅₀ of 93.25 ± 0.12 (μM), and for compound B (at 0.5 mM) was 69.23 ± 0.19 with IC₅₀ of 183.34 ± 0.13 (μM). Quercetin was used as standard control. It was conclued from the present study that caffeoyl-β-D-glucopyranoside and 1,3-dihydroxy-2-tetracosanoylamino-4-(E)-nonadecene isolated from methanol extract of aerial parts of Ranunculus muricatus posses antioxidant activity.