Solation, Purification and Identification of Antioxidant Compositions in Melilotus officinalis L / 中国药学杂志

ABSTRACT

OBJECTIVE: To study the chemical constituents from Melilotus officinalis(L.) and their anti-oxidant activities. METHODS: DPPH Assay and β-carotene bleaching assay were used for screening the fraction of anti-oxidant activity in the 70% ethanol extract of Melilotus officinalis(L.). The isolation and purification were performed by silica,Sephadex LH-20 and preparative columns. The structures of the obtained compounds were identified by physicochemical properties and spectral data. Then their anti-oxidant activities were evaluated. RESULTS: The ethyl acetate fraction from Melilotus officinalis(L.) showed the most significant anti-oxidant activity. Thirteen compounds were isolated and identified as kaempferol(1), luteolin(2), quercetin(3), hesperidin(4), rutin(5), apigenin(6), salicylic acid(7), coumarin(8), scoparone(9), 7-methoxycoumarin(10), fumaric acid(11), caffeic acid(12), and p-hydroxybenzoate-4-O-α-D-mannopyranosyl-(1→3)-α-L-rhamnoside(13).Compounds 2, 4, 7 and 12 exhibited strong scavenging activities against DPPH free radical with the IC50 values of 25.89, 14.09, 28.03, and 23.04 μg•mL-1, respectively; compounds 4, 7, 12 and 13 exhibited strong scavenging activities against ABTS free radical with the IC50 values of 10.48, 23.77, 22.79, and 25.20 μg•mL-1, respectively. CONCLUSION: Compounds 3, 7, 9, 10, 11, 12, and 13 are isolated from this plant for the first time. Compound 13 is a new compound not reported in the literature; compounds 2, 4, 7, and 12 have strong ability to scavenge DPPH free radicals; compounds 4, 7, 12, and 13 have strong ability to scavenge ABTS free radicals.